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Case Reports

Abstract

Cutaneous metastasis of non-cutaneous carcinoma is uncommon, with roughly 10% of metastatic carcinomas involving the skin. Tonsillar squamous cell carcinoma (SCC) is the most common oropharyngeal malignancy, and cutaneous metastasis is reportedly rare, with only six cases reported in the literature.

A 57 year old Caucasian male with a history of smoking presented with a new plaque-like, 10cm thickened erythematous area on the skin of his left neck overlying level 2 and 3. Three months prior, the patient had completed chemoradiation therapy (70 Gy and weekly cisplatin) for Stage 3, p16+ squamous cell carcinoma of the left tonsil and bulky lymphadenopathy of level 2 and 3. During this treatment, radiation dermatitis to the left face and neck had been managed with silvadine and was resolved prior to development of this new lesion. Histopathologic examination revealed basaloid squamous cell carcinoma. Many lymphovascular tumor emboli were also noted. The patient was subsequently started on pembrolizumab therapy which led to complete clinical resolution of the lesion after two cycles administered six weeks apart. A restaging PET-CT from skull to mid-thigh did not reveal any evidence of distant metastasis, suggesting only local dissemination of the tumor to the overlying skin.

This case highlights a rare cutaneous metastasis from a primary, HPV-related tonsillar SCC. Knowledge of the clinical history is essential to avoid a pitfall diagnosis of cutaneous carcinoma. The responsiveness of this metastasis to pembrolizumab therapy highlights the importance of prompt biopsy of new skin lesions in patients previously diagnosed with tonsillar SCC.