Microcystic Adnexal Carcinoma
Differential Diagnosis: The classic differential diagnosis for MAC is desmoplastic trichoepithelioma, syringoma, and infiltrative/morpheaform basal cell carcinoma (Figure 10, A through C).
With microcystic adnexal carcinoma
it is difficult to differentiate from infiltrating basal cell carcinoma and desmoplastic trichoepithelioma.
BerEP4 has been found to be able to differentiate BCC from other cutaneous pathologies such as squamous cell carcinoma, basosquamous cell carcinoma, collision tumors, sebaceoma, microcystic adnexal carcinoma
, ameloblastoma, epidermoid cysts, actinic keratosis, seborrheic keratosis, poroma, lichen planus like keratosis, nevi, hemangioma, inverted follicular keratosis, squamous intraepithelial neoplasia, and sebaceous adenoma/hyperplasia.
Expression of p75 neurotrophin receptor in desmoplastic trichoepithelioma, infiltrative basal cell carcinoma, and microcystic adnexal carcinoma
. Am J Dermatopathol.
Hence although formerly thought to be of mixed origin now syringoma is considered to be benign appendage tumour of intra- epidermal eccrine sweat duct.Histopathological differential diagnosis should be fibrosing basal cell carcinoma desmoplastic trichoepithelioma microcystic adnexal carcinoma
. Differentiating point from fibrosing basal cell carcinoma is that latter lacks ductal structure containing amorphous material.
The more common subtypes include microcystic adnexal carcinoma
, eccrine porocarcinoma, and hidradenocarcinoma.
Histopathologically, the deep and plaque types can be mistaken for microcystic adnexal carcinoma
. (68,69) We did not identify any unusual variants of syringoma, such as giant, plaque-like, or clear cell variants.
Based on the results of the database search, 27 cases were retrieved from the University of Pittsburgh Medical Center archives for the study: 12 cases of ductal CMBC (44%), which included 11 cases with morphologies not otherwise specified and 1 case of basal phenotype; 11 cases of SGC (41%), which included 5 cases of EC, 3 cases of porocarcinoma (PC), and 3 cases of microcystic adnexal carcinoma
(MAC); and 4 additional, randomly selected cases (15%), which included 2 primary cutaneous adnexal benign neoplasms (a poroma and an apocrine adenoma) and 2 cases of PBC.