Abstract:

Despite its presumed epidermal origin, Merkel cell carcinomas are usually intradermal without an epidermal component. When an epidermal component is found, particularly if it is focal, the involvement is thought to be an epidermotropic component of the dermal component. Recently, however, several authors have published cases of de novo Merkel cell carcinoma in situ (MCCIS) without a dermal component. In most of these cases, the MCCIS arose in association with another epidermal neoplasm, namely, squamous cell carcinoma in situ. Situated usually adjacent to SCCIS, MCCIS consists of full thickness atypical basophilic cells indistinguishable those cells found in dermal MCC. Merkel cell hyperplasia (MCH) on chronically sun-damaged skin is a long known phenomenon but its histopathologic findings have not been widely described. Here in, retrospective analysis of 62 MCCs diagnosed from 1/2002-8/2021 were performed. Out of 62 cases, 3 cases were MCH, 1 case was MCCis and 6 cases were dermal MCCs with epidermotropism. The remaining were typical MCCs with dermal involvement. For all cases of MCH/MCCis, excision was recommended, but no patient follow up is available. Literature search revealed 18 cases of MCCIS (MCH was not distinguished), 10 cases were without patient outcomes, and 9 cases reported no recurrence but only followed patients for 1-3 years. Only one case had recurrence as dermal MCC, with lymph node metastasis and death, 11 years after initial MCH. Because of the unknown biologic potential and rarity of MCH/MCCIS, the lesion should be removed with clear margins and patient followed for recurrence.

Financial Disclosure:
No current or relevant financial relationships exist.

Menu

Viral Patel, MD