This elderly women presented with a solitary flesh-colored papule on her lip. Clinically, an epidermoid cyst was suspected. Microcystic adnexal carcinomas (MACs) are rare tumors. They often present on the central face of women, as in this case, with a wide age range. While the incidence is low, the number of times it is included in the differential diagnosis on a superficial shave biopsy is high. Histologically, it mimics other sclerosing adnexal tumors, such as desmoplastic trichoepithelioma and syringoma. MACs tend to infiltrate deep, in the shape of an iceberg, with perineural invasion, while the others are more 'V' shaped and superficial. This is why seeing the entire lesion on biopsy is paramount. Recurrences are common as the borders of the lesion are difficult to define. Cool case!
The infiltrating tumor consists of small basaloid cells with minimal cytoplasm. They are fairly monomorphic. Mitoses are observed, but sparse.