Cutaneous metastasis of tonsillar carcinoma: Report of a rare case

Metastatic Tonsil Squamous Cell Carcinoma: An Important Consideration in the Differential Diagnosis of Malignant Basaloid Neoplasms in the Skin: Case Report and Review of the Literature

ABSTRACT

Malignant basaloid neoplasms of the skin are frequent, and their accurate diagnosis holds paramount importance for treatment and prognosis. However, these neoplasms can present diagnostic challenges because of their extensive differential diagnosis, which encompasses cutaneous metastasis among many other possibilities. We present a case of a 74-year-old man with a history of p16-positive palatine tonsil squamous cell carcinoma (SCC) treated with surgery and adjuvant radiation with no prior evidence of recurrence who presented to the dermatologist with 2 chin papules. The initial histopathologic evaluation of these lesions showed poorly differentiated malignant basaloid neoplasms. Subsequently, these biopsies were compared with the previous biopsies from his tonsil and lymph node, which showed similar findings including positive p16 staining and positive molecular testing for human papillomavirus-16, confirming the diagnosis of cutaneous metastasis from his previously diagnosed human papillomavirus-related tonsil SCC. Additional imaging studies found metastases to internal organs including the brain, and he was started on chemotherapy, immunotherapy, and radiation therapy. Cutaneous metastases from tonsil SCC are exceedingly rare, and only 5 cases have been described. Furthermore, this is the first case confirming the presence of high-risk human papillomavirus by molecular studies within the cutaneous metastases. The presented case underscores the importance of recognizing this unusual manifestation of tonsil SCC metastatic to the skin along with a good clinical patient history, ensuring accurate and prompt diagnosis and treatment of this condition.

Epidermotropic metastasis of squamous cell carcinoma of the tonsil: A case report with molecular confirmation

Metastasis of oropharyngeal squamous cell carcinoma (SCC) to skin is uncommon and portends a poor prognosis. Clinical history and histopathology are key to discerning between metastatic disease vs de novo SCC of the skin. We describe a case of an HPV+ tonsillar SCC in a 77-year-old male, with metastasis to the neck skin. This case is unique because of prominent in situ epidermal involvement on skin biopsy specimen, complicating the distinction between primary and secondary disease. The nature of the lesion was resolved using next-generation sequencing of both the primary oropharyngeal SCC and skin lesion biopsy specimens. Both tumors showed identical ATR D1639G somatic mutations, while the skin lesion contained an additional POLE F1366L mutation. Clonal evolution of metastatic lesions is a well-described phenomenon; comparing the genetic profiles of primary and metastatic specimens can be useful in evaluating the tumor origin as well as identifying targetable genetic aberrations.