Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer after basal cell carcinoma.1 With an estimated 700,000 cases reported annually in the United States, the incidence of cSCC continues to increase.2 Most patients with cSCC have an excellent prognosis after surgical clearance, with Mohs micrographic surgery (MMS) being the most successful treatment, followed by excision and electrodesiccation and curettage. A subset of patients with cSCC carry an increased risk of local recurrence, lymph node metastasis, and disease-specific death. A meta-analysis of 36 studies found that statistically significant risk factors for recurrence of cSCC included thickness greater than 2 mm (risk ratio [RR], 9.64; 95% CI, 1.30-1.52), invasion beyond the subcutaneous fat (RR, 7.61; 95% CI, 4.17-13.88), perineural invasion (RR, 4.30; 95% CI, 2.80-6.60), diameter greater than 20 mm (RR, 3.22; 95% CI, 1.91-5.45), location on temple (RR, 3.20; 95% CI, 1.12-9.15), and poor differentiation (RR, 2.66; 95% CI, 1.72-4.14).3 Additional risk factors for cSCC metastasis included location on the temple, ear, or lip, as well as a history of immunosuppression. Factors for disease-specific death were diameter greater than 20 mm, poor differentiation, location on the ear or lip, invasion beyond the subcutaneous fat, and perineural invasion.3 Perineural and/or lymphovascular invasion is considered high risk, but despite being linked to negative outcomes, there are no treatment guidelines based on lymphovascular (intravascular) invasion.4 We present a case of intravascular involvement found during MMS and treated with adjuvant radiotherapy after surgery. We share this case with the goal of discussing management in such cases and highlighting the need for improved definitive guidelines for high-risk cSCCs.
Case Report
A 72-year-old man presented with a rapidly growing lesion on the left side of the forehead of 1 year’s duration. His medical history was remarkable for B-cell lymphoma, which was currently in remission following chemotherapy 10 years prior. The lesion started as a small, red, dry patch that the patient initially thought was eczema. The site progressively enlarged to a red tumor measuring 2.4×2.0 cm (Figure 1), and the patient presented to the dermatology department for further evaluation. There was no clinical evidence of lymphadenopathy. A skin biopsy confirmed a moderately differentiated cSCC with a positive deep margin (Figure 2). Due to the tumor’s location, histology, size, and poorly defined borders, the patient was referred for treatment with MMS. The lesion was removed in a total of 2 stages and 4 sections. In addition to a proliferation of spindled tumor cells seen during surgery, which was consistent with cSCC, an intravascular component was noted despite clear margins after the surgery (Figure 3). The aggressive histology of intravascular involvement was subsequently confirmed by the academic dermatopathologist at our institution. With the evidence of an intravascular component of this patient’s cSCC, there was concern about further metastatic disease. After discussing the more aggressive histology type and size of the cSCC with the patient, he underwent subsequent computed tomography of the head, neck, and chest. Fortunately, this imaging did not show evidence of metastatic disease; thus, final staging of the cSCC was cT2N0M0. After interdisciplinary discussion and consultation with radiation oncology, the site of the cSCC was treated with adjuvant radiotherapy. The patient received a total of 6600 cGy delivered in 33 fractions of 200 cGy, each using an en face technique and 6 eV over a total treatment course of 48 days.
Figure 1. Clinical appearance of a moderately differentiated cutaneous squamous cell carcinoma at presentation for Mohs micrographic surgery.
Figure 2. Moderately differentiated cutaneous squamous cell carcinoma (cSCC) noted in surgical debulk for Mohs micrographic surgery (A)(H&E, original magnification ×4). Stage I of Mohs surgery revealed deeply infiltrative and moderately differentiated cSCC (B)(H&E, original magnification ×4).
Figure 3. Intravascular cutaneous squamous cell carcinoma noted in stage I of Mohs micrographic surgery (H&E, original magnification ×4). Of note, stage II revealed no residual tumor.
One year after undergoing MMS and adjuvant radiotherapy, the patient remains free of cSCC recurrence or metastases and still undergoes regular interdisciplinary monitoring. Without clear guidelines on the treatment of patients with intravascular involvement of cSCC, we relied on prior experience with similar cases.