Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer, mainly affecting non-Hispanic whites, with the head and neck being the most common sites. Its incidence is higher among immunosuppressed individuals, including organ transplant recipients (OTRs). We present an OTR, with multiple non-melanoma skin cancers (NMSCs), diagnosed with MCC on the right lateral shin, underscoring the need for vigilance in OTRs, regardless of lesion location or NMSC history.

A 75-year-old Caucasian male, seven years post-lung transplant on immunosuppressive medications with heavy NMSC history, presented with a 1-month history of a nodule on his right lateral shin. Physical examination revealed a 2-cm pink, firm nodule. Differential diagnosis included NMSC only. Biopsy showed sheets of small, basophilic cells filling the dermis, positive for CK20 (perinuclear dot-like), synaptophysin, and chromogranin, and negative for MCPyV and TTF-1, confirming MCC. A baseline PET/CT scan was negative. Wide local excision with sentinel lymph node biopsy showed metastasis to the right inguinal basin. The patient was started on Vusolimogene oderparepvec but unfortunately succumbed to metastatic disease three months later.

Our case highlights the importance of considering MCC in the differential diagnosis of new cutaneous lesions, particularly in OTRs, even if the lesion is not on the head/neck. The threshold for biopsy should be lower in these patients to ensure prompt diagnosis and treatment. This case also emphasizes that that even though NMSC may be more common in this population, new NMSC-like lesions should not be assumed to be NMSC without histological confirmation.

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Luis Borda, M.D.