An Unusual Morphological Presentation of Cutaneous Squamous Cell Carcinoma Mimicking Microcystic Adnexal Carcinoma: A Diagnostic Pitfall

Abstract

Cutaneous squamous cell carcinoma (SCC) exhibiting microcystic adnexal carcinoma-like differentiation is an extremely rare tumor that shows both squamous and ductal differentiation. This tumor is often misdiagnosed clinically and histologically and is confused with other malignant and benign cutaneous neoplasms. It usually occurs in middle-aged to older adults. Here, we report a case of SCC with microcystic adnexal carcinoma-like differentiation on the left chin of a 71-year-old male. The histopathological examination revealed a nodular tumor infiltrating the dermis, subcutaneous fat, and striated muscle tissue, consisting of both prominent atypical squamous differentiation and foci of duct-like structures.

Squamoid eccrine ductal carcinoma: a case report

“…Therefore, superficial biopsies may lead to a misdiagnosis of SCC as the biopsy specimen will most likely be composed of tissues showing a squamous differentiation [2,9,10]. The differential diagnosis includes SCC, metastatic carcinoma, microcystic carcinoma with squamous differentiation, porocarcinoma with squamous differentiation, Merkel cell carcinoma, and benign neoplasms [1,11].…”

Collision tumor of microcystic adnexal carcinoma and squamous cell carcinoma discovered on Mohs sections

“…There are similar, yet different cases described in the literature: a case of both SCC and MAC existing within an ovarian cystic teratoma, a case of MAC-like SCC involving the facial nerve, and a case of SCC with MAC-like differentiation of the chin. [4][5][6] Additionally, there are reported cases of MAC initially misdiagnosed as SCC owing to shallow biopsy techniques. 3 Although most of our patient's lesion was characteristic of MAC, it represents a collision tumor given the distinct SCC and MAC histologic features.…”