Satellite PGs are rare, usually occurring after treatment or manipulation of a solitary nodule.7,25,37 Spontaneous occurrence is rare.7,38 Satellite lesions are smooth, red, sessile papules that range in diameter from 1 to 10 mm. Unlike solitary PGs, satellite PGs most commonly appear on the trunk.7,39
Subcutaneous PGs also are uncommon and appear as nonspecific subcutaneous nodules.4,11,40 Because the clinical appearance of this tumor is quite different from that of cutaneous PG, subcutaneous PG is often difficult to diagnose based on clinical features. It is sometimes mistaken for a hemangioma or an epidermal cyst. Biopsy results readily distinguish it from granulation tissue or from other vascular entities.
Intravenous PGs may appear as subcutaneous nodules with nonspecific features, most commonly developing on the upper limb.6,41 Intravenous PG also may be evident as a red-brown polyp.41 Clinical diagnosis of intravenous PG can be difficult, as it can be mistaken for an organizing thrombus.
Congenital PG is an uncommon disseminated variant.2,42 Multiple lesions, similar in appearance to the cutaneous form, are present at birth. The condition appears to follow a benign course, with spontaneous resolution over 6 to 12 months.
Differential Diagnosis The differential diagnosis of PG should include amelanotic melanoma,43 angiosarcoma, basal cell carcinoma, squamous cell carcinoma, Kaposi sarcoma,44 hemangioma, bacillary angiomatosis,45-47 metastatic visceral malignancies,48 and granulation tissue. A case of hepatocellular metastases to the gingiva mimicking PG also has been reported.49
Histology Early PG is histologically identical to granulation tissue, appearing as highly vascularized connective tissue with capillaries and venules in an edematous matrix.2,3 As the lesion matures, a fibromyxoid stroma separates the lesions into lobules containing aggregates of capillaries and venules with plump endothelial cells.3 By this point, the edema has resolved. The epidermis exhibits inward growth at the lesion base, forming a so-called epidermal collarette and causing slight pedunculation. Extensive fibrosis signifies the final stage of regression.
Treatment and Prognosis Various treatment modalities have been used to remove PG. Effective means include excision, shave excision, laser surgery, sclerotherapy, electrodesiccation, curettage, ligation, or a combination of methods.
Excision with linear closure offers the lowest recurrence rate and allows histologic examination of a tissue sample. Closure, however, leaves a linear scar.50 Shave excision followed by argon laser photocoagulation is an effective therapeutic alternative that minimizes scar formation while preserving the ability to confirm the diagnosis with histologic examination.50
More conservative methods such as 585-nm flashlamp-pumped pulsed-dye laser surgery are beneficial but require multiple treatments and can only be used for small lesions.51 A 100% cure rate was observed with ethanolamine oleate sclerotherapy on both large and small lesions.52 Recurrence rate with shave excision plus cauterization or cauterization alone has been reported to be 43.5%.2 None of these tissue-preserving methods allows histologic examination. The lack of histologic confirmation should not pose a problem for experienced dermatologists or in clinically obvious cases. However, in one series, 18% of PGs were incorrectly diagnosed.50
Surgical debulking of cutaneous lesions followed by cauterization with silver nitrate has been advocated as an effective yet inexpensive treatment. Follow-up should occur weekly, with repeat cauterization as needed. This regimen results in an 85% resolution rate in an average of 1.6 treatments.53
Peduncular PGs may be ligated at the base using absorbable suture.54 The tumor is lifted with forceps and ligated at the base with tight suture knots. The tumor will become necrotic and fall off over several days. The procedure is atraumatic and inexpensive and requires no anesthesia or special equipment. Persistence or recurrence can be treated with excision or laser surgery. However, the procedure does not allow histologic examination.
Conclusion
PG is an acquired vascular neoplasm of considerable interest.55-60 Its friability often produces an enhanced level of clinical concern. PG needs to be distinguished from Kaposi sarcoma, melanoma, and metastatic carcinoma, as well as an important systemic bacterial infection, bacillary angiomatosis.