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Presentation of a Rare Malignancy: Leiomyosarcoma of the Prostate

Prostatic leiomyosarcoma is an aggressive malignancy with a high risk of metastasis and a poor prognosis that poses unique diagnostic and treatment challenges.

Prostatic leiomyosarcoma is a rare tumor.1 This neoplasm is composed of highly aggressive prostatic smooth muscle cells that present with nonspecific signs and symptoms mimicking other forms of prostatic pathology. Of the primary prostatic sarcomas, leiomyosarcoma represents the most common subtype in adults and is found in 38% to 52% of newly diagnosed prostate sarcoma.1,2 The prognosis is poor, and no clear guidelines exist regarding the optimal treatment approach. We report a case of prostate leiomyosarcoma and describe the disease characteristics, diagnostic modalities, and treatment approach regarding these rare malignancies.

Case Presentation

A 72-year-old male presented with 6 months of progressive severe lower urinary tract symptoms (LUTS) secondary to bladder outlet obstruction. The patient was refractory to medical management with combination α-blocker and 5-α-reductase inhibitor therapy and continued to require multiple emergent bladder catheterizations. Workup with urinalysis, blood biochemistry, and prostate specific antigen (PSA) levels were persistently normal. He reported no hematuria, weight loss, or perineal pain. The patient reported no history of tobacco use, exposure to hazardous chemicals, and had no family history of genitourinary cancers. On rectal exam, the prostate was firm and nodular, with induration noted along the right upper lobe of the prostate.

The patient was referred for a urology consultation and subsequently underwent transurethral resection of the prostate (TURP) for suspected severe benign prostatic hypertrophy (BPH). A histopathologic examination demonstrated atypical cytology consistent with high- grade leiomyosarcoma. Immunohistochemical analysis revealed positive staining for vimentin, smooth muscle actin, desmin (partial), cytokeratin, smooth muscle myosin, muscle specific actin, and Ki-67 (50%-60% expression).

Fluorodeoxyglucose positron emission tomography (FDG-PET) scan revealed a 5.7 x 5.9 cm tumor with a maximum standardized uptake value (SUVmax) of 12.6 in the right posterior prostate, without evidence of metastatic disease (Figures 1A and 1B). 

fed0360130s_f1.png
The patient was referred to medical and radiation oncology. He was evaluated for radical prostatectomy and planned for surgery with neo-adjuvant radiation. He received palliation of his symptoms with bilateral nephrostomy tubes; however, the patient had significant comorbidities and died prior to treatment.

Discussion

Originating from prostatic interstitial cells, prostatic leiomyosarcoma is a rare tumor that accounts for < 0.1% of all primary prostatic malignancies.1 Since its first description in 1950 by Riba and colleagues, < 200 cases have been reported worldwide.2 Among the sarcomas of the prostate, it is the most common tumor, accounting for around 38% to 52% of prostate sarcoma presentations.1,2

Patients typically present between the ages of 41 and 78 years (mean age 61 years).2,3 Signs and symptoms at presentation may vary; however, the most common symptoms are related to lower urinary tract obstruction (89.4% of patients). These symptoms include urinary frequency, urgency, nocturia, and may mimic the presentation of BPH.

Symptoms commonly associated with other malignancies, including constitutional symptoms such as weight loss, tend to occur less frequently or may be absent. Perineal or rectal pain may only be present in 25.6% of patients. Hematuria, burning on ejaculation, and constitutional symptoms are a less common presentation (< 10% of patients).3,4 PSA levels typically do not rise and are found to be within normal limits. The lack of PSA elevation is related to the tumors nonepithelial origin and may contribute to a delay in diagnosis.2,4,5

 

 

Diagnosis

Diagnosis may be further eluded as digital rectal exam (DRE) findings tend to reveal nonspecific enlargement of the prostate, resembling that of BPH. DRE may show a hard and firm prostate with nodular induration at the base or over the lobes of the prostate.6 At this stage a urology consultation is useful, as diagnosis is most commonly achieved using transrectal ultrasound (TRUS) with ultrasound-guided needle biopsy or after a TURP procedure.3

Prostate sarcoma is associated with markedly enlarged prostate volume, irregular margins with invasion, or heterogenous hypoechoic lesions on TRUS.7 Transperineal biopsy, computed tomography (CT)-guided biopsy, or suprapubic prostatectomy have been less frequently employed for diagnosis in previously reported cases.8 Specialized imaging modalities, such as CT scan or bone scan, do not show any specific findings with regards to these tumors; their role is limited to evaluation of the local and distant metastasis and for follow-up assessments.9 Transabdominal ultrasound may assess hydronephrosis or enlarged prostate and its relation to nearby structures, although it has not been shown to be helpful in establishing a specific diagnosis.6

Histologically, prostatic leiomyosarcoma is a distinct subtype of prostatic sarcoma. Other subtypes include stromal tumors such as rhabdomyosarcoma, fibrosarcoma, and spindle cell sarcoma.2 The majority of leiomyosarcomas are high-grade lesions demonstrating neoplastic spindle cells with nuclear atypia, multifocal necrosis, and cystic degeneration. Low-grade leiomyosarcomas are very rare.10 Immunohistochemistry is characteristically positive for vimentin, smooth muscle actin, and desmin expression. Cytokeratin may be positive in up to 25% of cases, whereas S-100, CD34, CD117, and PSA are negative.2,3 These histopathological findings help to differentiate leiomyosarcoma from other prostatic tumors.

Tumor size may vary greatly, and measurements have been reported to range from 3 cm to 21 cm, frequently presenting with invasion of local structures.11 Advanced stage disease is commonly found at initial diagnosis and is thought to be due to the lack of early specific symptoms. Metastatic disease at presentation may be found in up to one-third of patients, with the lungs being the most common site of metastasis followed by the liver. Local extent and distant spread of disease may be determined by CT or magnetic resonance imaging (MRI) scans, which provide clear delineation of neoplastic and nonneoplastic tissues. 

fed0360130s_f2.png
These imaging techniques are important in assessing surgical respectability or potential for radiotherapy.  Brain metastasis is a rare finding (3.6% of cases); therefore, imaging of the brain is not routinely performed unless high clinical suspicion of brain involvement is present.3,5,8 FDG-PET scans have become more readily available in clinical practice over recent years and have found use in staging prostatic sarcoma. Leiomyosarcomas, in particular, have been found to be FDG avid, and SUVmax has been utilized as a likely predictor of tumor size and grade (Figure 2).11

Treatment

Treatment regimens may include a multimodal approach of combination surgery, radiation, and chemotherapy. However, there are currently no standardized guidelines for treatment and the optimal therapy remains unknown.2,3,6 Surgery remains the mainstay of treatment, and patients with surgically resectable tumors are treated with curative intent. Surgeries performed include radical retropubic prostatectomy, radical cystoprostatectomy, suprapubic prostatectomy, and pelvic exenteration.2,5,8,12 These operations may be preceded or followed by radiation therapy and/or chemotherapy depending on extent of disease.

 

 

It has been reported that neo-adjuvant chemotherapy and/or radiotherapy can aid in decreasing tumor burden to facilitate a complete resection.2,8,13,14 Patients who are determined to not be candidates for surgery or whom have widespread disease may be offered systemic chemotherapy. Chemotherapy regimens vary, but common regimens include anthracyclines (doxorubicin or epirubicin), alkylating agents (cyclophosphamide, ifosfamide, dacarbazine), and/or vinca alkaloids (vinblastine or vincristine). Patients who do not receive surgical intervention rarely achieve a sustained remission.3,5,8

The long-term prognosis of prostatic leiomyosarcoma is poor due to the aggressive nature of the neoplasm and the high chance of disease recurrence or metastasis. Median survival is estimated at 17 months, and from 50% to 75% of patients die within 2 to 5 years of diagnosis.2,3 Prognosis may be improved in patients with localized disease at diagnosis who are candidates for complete surgical resection with negative margins.13 Adverse prognostic factors include metastatic disease at presentation and the presence of positive surgical margins after surgery.

Overall survival is very poor, and it is estimated that the 1-, 3-, and 5-year survival rates are 68%, 34%, and 26%, respectively.3 However, some studies estimate the 5-year survival to be anywhere from 0 to 60%.8,9 Due to the substantially high risk of death, prostatic leiomyosarcoma may be one of the most aggressive and poorly prognostic malignancies involving the prostate.

Conclusion

Prostatic leiomyosarcoma poses a unique diagnostic challenge, as clinical presentation alone may not always be suggestive of underlying malignancy. This challenge is further exacerbated by its aggressive nature, high risk of metastasis, and difficulties with unclear treatment. Proper history and physical examination, differential diagnosis, and a multidisciplinary approach to patient care are the foundation for early detection and promoting improved survival.

Author disclosures
The authors report no actual or potential conflicts of interest with regard to this article.

Disclaimer
The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.

References

1.  Miedler JD, MacLennan GT. Leiomyosarcoma of the prostate. J Urol. 2007;178(2):668.

2.  Zazzara M, Divenuto L, Scarcia M, Cardo G, Maselli FP, Ludovico GM. Leiomyosarcoma of prostate: case report and literature review. Urol Case Rep. 2018;17:4-6.

3.  Vandoros GP, Manolidis T, Karamouzis MV, et al. Leiomyosarcoma of the prostate: case report and review of 54 previously published cases. Sarcoma. 2008;2008:458709.

4.  Talapatra K, Nemade B, Bhutani R, et al. Recurrent episodes of hematuria: a rare presentation of leiomyosarcoma of prostate. J Cancer Res Ther. 2006;2(4):212-214.

5.  Cheville JC, Dundore PA, Nascimento AG, et al. Leiomyosarcoma of the prostate. Report of 23 cases. Cancer. 1995;76(8):1422-1427.

6.  Venyo AK. A review of the literature on primary leiomyosarcoma of the prostate gland. Adv Urol. 2015;2015:485786.

7.  Stilgenbauer R, Benedict M, Bamshad R, Viduetsky A. Sarcoma of the prostate: sonographic findings and pathologic correlation. J Ultrasound Med. 2007;26(12):1789-1793.  

8.  Sexton WJ, Lance RE, Reyes AO, Pisters PW, Tu SM, Pisters LL. Adult prostate sarcoma: the M.D. Anderson Cancer Center experience. J Urol. 2001;166(2):521-525.

9.  Singh JP, Chakraborty D, Bera MK, Pal D. Leiomyosarcoma of prostate: a rare, aggressive tumor. J Cancer Res Ther. 2013;9(4):743-745.

10.  Hansel DE, Herawi M, Montgomery E, Epstein JI. Spindle cell lesions of the adult prostate. Mod Pathol. 2007;20(1):148-158.

11.  Punt SE, Eary JF, O'Sullivan J, Conrad EU. Fluorodeoxyglucose positron emission tomography in leiomyosarcoma: imaging characteristics. Nucl Med Commun. 2009;30(7):546-549.

12.  Dotan ZA, Tal R, Golijanin D, et al. Adult genitourinary sarcoma: the 25-year Memorial Sloan-Kettering experience. J Urol. 2006;176(5):2033-2038.

13. Musser JE, Assel M, Mashni JW, Sjoberg DD, Russo P. Adult prostate sarcoma: the Memorial Sloan Kettering experience. Urology. 2014;84(3):624-628.

14. Janet NL, May AW, Akins RS. Sarcoma of the prostate: a single institutional review. Am J Clin Oncol. 2009;32:27-29

Author and Disclosure Information

Daniel Ermann is an Internal Medicine Resident; Victoria Noble and Brittany Thomas are Medical Students; Hafiz Fazeel is a Graduate Student; and Peter Silberstein is Chief of Hematology/ Oncology; all at Creighton University Medical Center in Omaha, Nebraska. Correspondence: Daniel Ermann (danielermann@ creighton.edu)

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Daniel Ermann is an Internal Medicine Resident; Victoria Noble and Brittany Thomas are Medical Students; Hafiz Fazeel is a Graduate Student; and Peter Silberstein is Chief of Hematology/ Oncology; all at Creighton University Medical Center in Omaha, Nebraska. Correspondence: Daniel Ermann (danielermann@ creighton.edu)

Author and Disclosure Information

Daniel Ermann is an Internal Medicine Resident; Victoria Noble and Brittany Thomas are Medical Students; Hafiz Fazeel is a Graduate Student; and Peter Silberstein is Chief of Hematology/ Oncology; all at Creighton University Medical Center in Omaha, Nebraska. Correspondence: Daniel Ermann (danielermann@ creighton.edu)

Prostatic leiomyosarcoma is an aggressive malignancy with a high risk of metastasis and a poor prognosis that poses unique diagnostic and treatment challenges.

Prostatic leiomyosarcoma is an aggressive malignancy with a high risk of metastasis and a poor prognosis that poses unique diagnostic and treatment challenges.

Prostatic leiomyosarcoma is a rare tumor.1 This neoplasm is composed of highly aggressive prostatic smooth muscle cells that present with nonspecific signs and symptoms mimicking other forms of prostatic pathology. Of the primary prostatic sarcomas, leiomyosarcoma represents the most common subtype in adults and is found in 38% to 52% of newly diagnosed prostate sarcoma.1,2 The prognosis is poor, and no clear guidelines exist regarding the optimal treatment approach. We report a case of prostate leiomyosarcoma and describe the disease characteristics, diagnostic modalities, and treatment approach regarding these rare malignancies.

Case Presentation

A 72-year-old male presented with 6 months of progressive severe lower urinary tract symptoms (LUTS) secondary to bladder outlet obstruction. The patient was refractory to medical management with combination α-blocker and 5-α-reductase inhibitor therapy and continued to require multiple emergent bladder catheterizations. Workup with urinalysis, blood biochemistry, and prostate specific antigen (PSA) levels were persistently normal. He reported no hematuria, weight loss, or perineal pain. The patient reported no history of tobacco use, exposure to hazardous chemicals, and had no family history of genitourinary cancers. On rectal exam, the prostate was firm and nodular, with induration noted along the right upper lobe of the prostate.

The patient was referred for a urology consultation and subsequently underwent transurethral resection of the prostate (TURP) for suspected severe benign prostatic hypertrophy (BPH). A histopathologic examination demonstrated atypical cytology consistent with high- grade leiomyosarcoma. Immunohistochemical analysis revealed positive staining for vimentin, smooth muscle actin, desmin (partial), cytokeratin, smooth muscle myosin, muscle specific actin, and Ki-67 (50%-60% expression).

Fluorodeoxyglucose positron emission tomography (FDG-PET) scan revealed a 5.7 x 5.9 cm tumor with a maximum standardized uptake value (SUVmax) of 12.6 in the right posterior prostate, without evidence of metastatic disease (Figures 1A and 1B). 

fed0360130s_f1.png
The patient was referred to medical and radiation oncology. He was evaluated for radical prostatectomy and planned for surgery with neo-adjuvant radiation. He received palliation of his symptoms with bilateral nephrostomy tubes; however, the patient had significant comorbidities and died prior to treatment.

Discussion

Originating from prostatic interstitial cells, prostatic leiomyosarcoma is a rare tumor that accounts for < 0.1% of all primary prostatic malignancies.1 Since its first description in 1950 by Riba and colleagues, < 200 cases have been reported worldwide.2 Among the sarcomas of the prostate, it is the most common tumor, accounting for around 38% to 52% of prostate sarcoma presentations.1,2

Patients typically present between the ages of 41 and 78 years (mean age 61 years).2,3 Signs and symptoms at presentation may vary; however, the most common symptoms are related to lower urinary tract obstruction (89.4% of patients). These symptoms include urinary frequency, urgency, nocturia, and may mimic the presentation of BPH.

Symptoms commonly associated with other malignancies, including constitutional symptoms such as weight loss, tend to occur less frequently or may be absent. Perineal or rectal pain may only be present in 25.6% of patients. Hematuria, burning on ejaculation, and constitutional symptoms are a less common presentation (< 10% of patients).3,4 PSA levels typically do not rise and are found to be within normal limits. The lack of PSA elevation is related to the tumors nonepithelial origin and may contribute to a delay in diagnosis.2,4,5

 

 

Diagnosis

Diagnosis may be further eluded as digital rectal exam (DRE) findings tend to reveal nonspecific enlargement of the prostate, resembling that of BPH. DRE may show a hard and firm prostate with nodular induration at the base or over the lobes of the prostate.6 At this stage a urology consultation is useful, as diagnosis is most commonly achieved using transrectal ultrasound (TRUS) with ultrasound-guided needle biopsy or after a TURP procedure.3

Prostate sarcoma is associated with markedly enlarged prostate volume, irregular margins with invasion, or heterogenous hypoechoic lesions on TRUS.7 Transperineal biopsy, computed tomography (CT)-guided biopsy, or suprapubic prostatectomy have been less frequently employed for diagnosis in previously reported cases.8 Specialized imaging modalities, such as CT scan or bone scan, do not show any specific findings with regards to these tumors; their role is limited to evaluation of the local and distant metastasis and for follow-up assessments.9 Transabdominal ultrasound may assess hydronephrosis or enlarged prostate and its relation to nearby structures, although it has not been shown to be helpful in establishing a specific diagnosis.6

Histologically, prostatic leiomyosarcoma is a distinct subtype of prostatic sarcoma. Other subtypes include stromal tumors such as rhabdomyosarcoma, fibrosarcoma, and spindle cell sarcoma.2 The majority of leiomyosarcomas are high-grade lesions demonstrating neoplastic spindle cells with nuclear atypia, multifocal necrosis, and cystic degeneration. Low-grade leiomyosarcomas are very rare.10 Immunohistochemistry is characteristically positive for vimentin, smooth muscle actin, and desmin expression. Cytokeratin may be positive in up to 25% of cases, whereas S-100, CD34, CD117, and PSA are negative.2,3 These histopathological findings help to differentiate leiomyosarcoma from other prostatic tumors.

Tumor size may vary greatly, and measurements have been reported to range from 3 cm to 21 cm, frequently presenting with invasion of local structures.11 Advanced stage disease is commonly found at initial diagnosis and is thought to be due to the lack of early specific symptoms. Metastatic disease at presentation may be found in up to one-third of patients, with the lungs being the most common site of metastasis followed by the liver. Local extent and distant spread of disease may be determined by CT or magnetic resonance imaging (MRI) scans, which provide clear delineation of neoplastic and nonneoplastic tissues. 

fed0360130s_f2.png
These imaging techniques are important in assessing surgical respectability or potential for radiotherapy.  Brain metastasis is a rare finding (3.6% of cases); therefore, imaging of the brain is not routinely performed unless high clinical suspicion of brain involvement is present.3,5,8 FDG-PET scans have become more readily available in clinical practice over recent years and have found use in staging prostatic sarcoma. Leiomyosarcomas, in particular, have been found to be FDG avid, and SUVmax has been utilized as a likely predictor of tumor size and grade (Figure 2).11

Treatment

Treatment regimens may include a multimodal approach of combination surgery, radiation, and chemotherapy. However, there are currently no standardized guidelines for treatment and the optimal therapy remains unknown.2,3,6 Surgery remains the mainstay of treatment, and patients with surgically resectable tumors are treated with curative intent. Surgeries performed include radical retropubic prostatectomy, radical cystoprostatectomy, suprapubic prostatectomy, and pelvic exenteration.2,5,8,12 These operations may be preceded or followed by radiation therapy and/or chemotherapy depending on extent of disease.

 

 

It has been reported that neo-adjuvant chemotherapy and/or radiotherapy can aid in decreasing tumor burden to facilitate a complete resection.2,8,13,14 Patients who are determined to not be candidates for surgery or whom have widespread disease may be offered systemic chemotherapy. Chemotherapy regimens vary, but common regimens include anthracyclines (doxorubicin or epirubicin), alkylating agents (cyclophosphamide, ifosfamide, dacarbazine), and/or vinca alkaloids (vinblastine or vincristine). Patients who do not receive surgical intervention rarely achieve a sustained remission.3,5,8

The long-term prognosis of prostatic leiomyosarcoma is poor due to the aggressive nature of the neoplasm and the high chance of disease recurrence or metastasis. Median survival is estimated at 17 months, and from 50% to 75% of patients die within 2 to 5 years of diagnosis.2,3 Prognosis may be improved in patients with localized disease at diagnosis who are candidates for complete surgical resection with negative margins.13 Adverse prognostic factors include metastatic disease at presentation and the presence of positive surgical margins after surgery.

Overall survival is very poor, and it is estimated that the 1-, 3-, and 5-year survival rates are 68%, 34%, and 26%, respectively.3 However, some studies estimate the 5-year survival to be anywhere from 0 to 60%.8,9 Due to the substantially high risk of death, prostatic leiomyosarcoma may be one of the most aggressive and poorly prognostic malignancies involving the prostate.

Conclusion

Prostatic leiomyosarcoma poses a unique diagnostic challenge, as clinical presentation alone may not always be suggestive of underlying malignancy. This challenge is further exacerbated by its aggressive nature, high risk of metastasis, and difficulties with unclear treatment. Proper history and physical examination, differential diagnosis, and a multidisciplinary approach to patient care are the foundation for early detection and promoting improved survival.

Author disclosures
The authors report no actual or potential conflicts of interest with regard to this article.

Disclaimer
The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.

Prostatic leiomyosarcoma is a rare tumor.1 This neoplasm is composed of highly aggressive prostatic smooth muscle cells that present with nonspecific signs and symptoms mimicking other forms of prostatic pathology. Of the primary prostatic sarcomas, leiomyosarcoma represents the most common subtype in adults and is found in 38% to 52% of newly diagnosed prostate sarcoma.1,2 The prognosis is poor, and no clear guidelines exist regarding the optimal treatment approach. We report a case of prostate leiomyosarcoma and describe the disease characteristics, diagnostic modalities, and treatment approach regarding these rare malignancies.

Case Presentation

A 72-year-old male presented with 6 months of progressive severe lower urinary tract symptoms (LUTS) secondary to bladder outlet obstruction. The patient was refractory to medical management with combination α-blocker and 5-α-reductase inhibitor therapy and continued to require multiple emergent bladder catheterizations. Workup with urinalysis, blood biochemistry, and prostate specific antigen (PSA) levels were persistently normal. He reported no hematuria, weight loss, or perineal pain. The patient reported no history of tobacco use, exposure to hazardous chemicals, and had no family history of genitourinary cancers. On rectal exam, the prostate was firm and nodular, with induration noted along the right upper lobe of the prostate.

The patient was referred for a urology consultation and subsequently underwent transurethral resection of the prostate (TURP) for suspected severe benign prostatic hypertrophy (BPH). A histopathologic examination demonstrated atypical cytology consistent with high- grade leiomyosarcoma. Immunohistochemical analysis revealed positive staining for vimentin, smooth muscle actin, desmin (partial), cytokeratin, smooth muscle myosin, muscle specific actin, and Ki-67 (50%-60% expression).

Fluorodeoxyglucose positron emission tomography (FDG-PET) scan revealed a 5.7 x 5.9 cm tumor with a maximum standardized uptake value (SUVmax) of 12.6 in the right posterior prostate, without evidence of metastatic disease (Figures 1A and 1B). 

fed0360130s_f1.png
The patient was referred to medical and radiation oncology. He was evaluated for radical prostatectomy and planned for surgery with neo-adjuvant radiation. He received palliation of his symptoms with bilateral nephrostomy tubes; however, the patient had significant comorbidities and died prior to treatment.

Discussion

Originating from prostatic interstitial cells, prostatic leiomyosarcoma is a rare tumor that accounts for < 0.1% of all primary prostatic malignancies.1 Since its first description in 1950 by Riba and colleagues, < 200 cases have been reported worldwide.2 Among the sarcomas of the prostate, it is the most common tumor, accounting for around 38% to 52% of prostate sarcoma presentations.1,2

Patients typically present between the ages of 41 and 78 years (mean age 61 years).2,3 Signs and symptoms at presentation may vary; however, the most common symptoms are related to lower urinary tract obstruction (89.4% of patients). These symptoms include urinary frequency, urgency, nocturia, and may mimic the presentation of BPH.

Symptoms commonly associated with other malignancies, including constitutional symptoms such as weight loss, tend to occur less frequently or may be absent. Perineal or rectal pain may only be present in 25.6% of patients. Hematuria, burning on ejaculation, and constitutional symptoms are a less common presentation (< 10% of patients).3,4 PSA levels typically do not rise and are found to be within normal limits. The lack of PSA elevation is related to the tumors nonepithelial origin and may contribute to a delay in diagnosis.2,4,5

 

 

Diagnosis

Diagnosis may be further eluded as digital rectal exam (DRE) findings tend to reveal nonspecific enlargement of the prostate, resembling that of BPH. DRE may show a hard and firm prostate with nodular induration at the base or over the lobes of the prostate.6 At this stage a urology consultation is useful, as diagnosis is most commonly achieved using transrectal ultrasound (TRUS) with ultrasound-guided needle biopsy or after a TURP procedure.3

Prostate sarcoma is associated with markedly enlarged prostate volume, irregular margins with invasion, or heterogenous hypoechoic lesions on TRUS.7 Transperineal biopsy, computed tomography (CT)-guided biopsy, or suprapubic prostatectomy have been less frequently employed for diagnosis in previously reported cases.8 Specialized imaging modalities, such as CT scan or bone scan, do not show any specific findings with regards to these tumors; their role is limited to evaluation of the local and distant metastasis and for follow-up assessments.9 Transabdominal ultrasound may assess hydronephrosis or enlarged prostate and its relation to nearby structures, although it has not been shown to be helpful in establishing a specific diagnosis.6

Histologically, prostatic leiomyosarcoma is a distinct subtype of prostatic sarcoma. Other subtypes include stromal tumors such as rhabdomyosarcoma, fibrosarcoma, and spindle cell sarcoma.2 The majority of leiomyosarcomas are high-grade lesions demonstrating neoplastic spindle cells with nuclear atypia, multifocal necrosis, and cystic degeneration. Low-grade leiomyosarcomas are very rare.10 Immunohistochemistry is characteristically positive for vimentin, smooth muscle actin, and desmin expression. Cytokeratin may be positive in up to 25% of cases, whereas S-100, CD34, CD117, and PSA are negative.2,3 These histopathological findings help to differentiate leiomyosarcoma from other prostatic tumors.

Tumor size may vary greatly, and measurements have been reported to range from 3 cm to 21 cm, frequently presenting with invasion of local structures.11 Advanced stage disease is commonly found at initial diagnosis and is thought to be due to the lack of early specific symptoms. Metastatic disease at presentation may be found in up to one-third of patients, with the lungs being the most common site of metastasis followed by the liver. Local extent and distant spread of disease may be determined by CT or magnetic resonance imaging (MRI) scans, which provide clear delineation of neoplastic and nonneoplastic tissues. 

fed0360130s_f2.png
These imaging techniques are important in assessing surgical respectability or potential for radiotherapy.  Brain metastasis is a rare finding (3.6% of cases); therefore, imaging of the brain is not routinely performed unless high clinical suspicion of brain involvement is present.3,5,8 FDG-PET scans have become more readily available in clinical practice over recent years and have found use in staging prostatic sarcoma. Leiomyosarcomas, in particular, have been found to be FDG avid, and SUVmax has been utilized as a likely predictor of tumor size and grade (Figure 2).11

Treatment

Treatment regimens may include a multimodal approach of combination surgery, radiation, and chemotherapy. However, there are currently no standardized guidelines for treatment and the optimal therapy remains unknown.2,3,6 Surgery remains the mainstay of treatment, and patients with surgically resectable tumors are treated with curative intent. Surgeries performed include radical retropubic prostatectomy, radical cystoprostatectomy, suprapubic prostatectomy, and pelvic exenteration.2,5,8,12 These operations may be preceded or followed by radiation therapy and/or chemotherapy depending on extent of disease.

 

 

It has been reported that neo-adjuvant chemotherapy and/or radiotherapy can aid in decreasing tumor burden to facilitate a complete resection.2,8,13,14 Patients who are determined to not be candidates for surgery or whom have widespread disease may be offered systemic chemotherapy. Chemotherapy regimens vary, but common regimens include anthracyclines (doxorubicin or epirubicin), alkylating agents (cyclophosphamide, ifosfamide, dacarbazine), and/or vinca alkaloids (vinblastine or vincristine). Patients who do not receive surgical intervention rarely achieve a sustained remission.3,5,8

The long-term prognosis of prostatic leiomyosarcoma is poor due to the aggressive nature of the neoplasm and the high chance of disease recurrence or metastasis. Median survival is estimated at 17 months, and from 50% to 75% of patients die within 2 to 5 years of diagnosis.2,3 Prognosis may be improved in patients with localized disease at diagnosis who are candidates for complete surgical resection with negative margins.13 Adverse prognostic factors include metastatic disease at presentation and the presence of positive surgical margins after surgery.

Overall survival is very poor, and it is estimated that the 1-, 3-, and 5-year survival rates are 68%, 34%, and 26%, respectively.3 However, some studies estimate the 5-year survival to be anywhere from 0 to 60%.8,9 Due to the substantially high risk of death, prostatic leiomyosarcoma may be one of the most aggressive and poorly prognostic malignancies involving the prostate.

Conclusion

Prostatic leiomyosarcoma poses a unique diagnostic challenge, as clinical presentation alone may not always be suggestive of underlying malignancy. This challenge is further exacerbated by its aggressive nature, high risk of metastasis, and difficulties with unclear treatment. Proper history and physical examination, differential diagnosis, and a multidisciplinary approach to patient care are the foundation for early detection and promoting improved survival.

Author disclosures
The authors report no actual or potential conflicts of interest with regard to this article.

Disclaimer
The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.

References

1.  Miedler JD, MacLennan GT. Leiomyosarcoma of the prostate. J Urol. 2007;178(2):668.

2.  Zazzara M, Divenuto L, Scarcia M, Cardo G, Maselli FP, Ludovico GM. Leiomyosarcoma of prostate: case report and literature review. Urol Case Rep. 2018;17:4-6.

3.  Vandoros GP, Manolidis T, Karamouzis MV, et al. Leiomyosarcoma of the prostate: case report and review of 54 previously published cases. Sarcoma. 2008;2008:458709.

4.  Talapatra K, Nemade B, Bhutani R, et al. Recurrent episodes of hematuria: a rare presentation of leiomyosarcoma of prostate. J Cancer Res Ther. 2006;2(4):212-214.

5.  Cheville JC, Dundore PA, Nascimento AG, et al. Leiomyosarcoma of the prostate. Report of 23 cases. Cancer. 1995;76(8):1422-1427.

6.  Venyo AK. A review of the literature on primary leiomyosarcoma of the prostate gland. Adv Urol. 2015;2015:485786.

7.  Stilgenbauer R, Benedict M, Bamshad R, Viduetsky A. Sarcoma of the prostate: sonographic findings and pathologic correlation. J Ultrasound Med. 2007;26(12):1789-1793.  

8.  Sexton WJ, Lance RE, Reyes AO, Pisters PW, Tu SM, Pisters LL. Adult prostate sarcoma: the M.D. Anderson Cancer Center experience. J Urol. 2001;166(2):521-525.

9.  Singh JP, Chakraborty D, Bera MK, Pal D. Leiomyosarcoma of prostate: a rare, aggressive tumor. J Cancer Res Ther. 2013;9(4):743-745.

10.  Hansel DE, Herawi M, Montgomery E, Epstein JI. Spindle cell lesions of the adult prostate. Mod Pathol. 2007;20(1):148-158.

11.  Punt SE, Eary JF, O'Sullivan J, Conrad EU. Fluorodeoxyglucose positron emission tomography in leiomyosarcoma: imaging characteristics. Nucl Med Commun. 2009;30(7):546-549.

12.  Dotan ZA, Tal R, Golijanin D, et al. Adult genitourinary sarcoma: the 25-year Memorial Sloan-Kettering experience. J Urol. 2006;176(5):2033-2038.

13. Musser JE, Assel M, Mashni JW, Sjoberg DD, Russo P. Adult prostate sarcoma: the Memorial Sloan Kettering experience. Urology. 2014;84(3):624-628.

14. Janet NL, May AW, Akins RS. Sarcoma of the prostate: a single institutional review. Am J Clin Oncol. 2009;32:27-29

References

1.  Miedler JD, MacLennan GT. Leiomyosarcoma of the prostate. J Urol. 2007;178(2):668.

2.  Zazzara M, Divenuto L, Scarcia M, Cardo G, Maselli FP, Ludovico GM. Leiomyosarcoma of prostate: case report and literature review. Urol Case Rep. 2018;17:4-6.

3.  Vandoros GP, Manolidis T, Karamouzis MV, et al. Leiomyosarcoma of the prostate: case report and review of 54 previously published cases. Sarcoma. 2008;2008:458709.

4.  Talapatra K, Nemade B, Bhutani R, et al. Recurrent episodes of hematuria: a rare presentation of leiomyosarcoma of prostate. J Cancer Res Ther. 2006;2(4):212-214.

5.  Cheville JC, Dundore PA, Nascimento AG, et al. Leiomyosarcoma of the prostate. Report of 23 cases. Cancer. 1995;76(8):1422-1427.

6.  Venyo AK. A review of the literature on primary leiomyosarcoma of the prostate gland. Adv Urol. 2015;2015:485786.

7.  Stilgenbauer R, Benedict M, Bamshad R, Viduetsky A. Sarcoma of the prostate: sonographic findings and pathologic correlation. J Ultrasound Med. 2007;26(12):1789-1793.  

8.  Sexton WJ, Lance RE, Reyes AO, Pisters PW, Tu SM, Pisters LL. Adult prostate sarcoma: the M.D. Anderson Cancer Center experience. J Urol. 2001;166(2):521-525.

9.  Singh JP, Chakraborty D, Bera MK, Pal D. Leiomyosarcoma of prostate: a rare, aggressive tumor. J Cancer Res Ther. 2013;9(4):743-745.

10.  Hansel DE, Herawi M, Montgomery E, Epstein JI. Spindle cell lesions of the adult prostate. Mod Pathol. 2007;20(1):148-158.

11.  Punt SE, Eary JF, O'Sullivan J, Conrad EU. Fluorodeoxyglucose positron emission tomography in leiomyosarcoma: imaging characteristics. Nucl Med Commun. 2009;30(7):546-549.

12.  Dotan ZA, Tal R, Golijanin D, et al. Adult genitourinary sarcoma: the 25-year Memorial Sloan-Kettering experience. J Urol. 2006;176(5):2033-2038.

13. Musser JE, Assel M, Mashni JW, Sjoberg DD, Russo P. Adult prostate sarcoma: the Memorial Sloan Kettering experience. Urology. 2014;84(3):624-628.

14. Janet NL, May AW, Akins RS. Sarcoma of the prostate: a single institutional review. Am J Clin Oncol. 2009;32:27-29

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