Microcystic adnexal carcinoma: A distinct clinicopathologic entity

Abstract

Microcystic adnexal carcinoma is an unusual locally aggressive neoplasm that is important to recognize since it may be confused with benign adnexal neoplasms, particularly desmoplastic trichoepithelioma, trichoadenoma, and syringoma. Six cases are described all of which displayed benign histological features on initial biopsy. Most often these neoplasms presented as solitary flesh‐colored indurated plaques on the upper lip. All patients were white, five were women, and the average age was 44‐years‐old. Islands of basaloid keratinocytes, some of which contained horn cysts and abortive follicles, were embedded in a desmoplastic stroma. In other foci, ducts and gland‐like structures lined by a two‐cell layer predominated. In deep components individual and thin strands of cells dissected collagen bundles and skeletal muscle and invaded perineural spaces. Despite this, cytologic atypia and mitotic figures were rare. The cell of origin is considered to be a pluripotential adnexal keratinocyte which is capable of both follicular and sweat gland differentiation.

Malignant adnexal neoplasms

“…As with acral melanomas, amputation at or above the nearest joint is one recommended strategy for local control. [180][181][182] Aggressive digital papillary adenoma/ adenocarcinoma…”

“…As with acral melanomas, amputation at or above the nearest joint is one recommended strategy for local control. [180][181][182] In part because of the rarity of these tumors, modern surgical approaches such as sentinel lymphadenectomy that are commonplace for melanomas are reportable as isolated cases when applied to the digital papillary eccrine tumors. 204,205 Currently, the use of aggressive local surgical extirpation is generally advised for any digital papillary eccrine neoplasm as the 'originally proposed criteria for distinguishing benign (adenoma) and malignant (adenocarcinoma) do not necessarily predict biological behaviour'.…”

“…Typically a neoplasm of the mid-face of young, middle-aged or elderly woman, it has a tendency toward persistent and stubborn local recurrence, but not to metastatic deposits. 182,[206][207][208][209] In particular, the upper lip and the glabella are common locations; rarely, tumors appear outside the head and neck in locations such as the axilla. Local recurrence rates are approximately 50%.…”

Sclerosing Microcystic Adenocarcinoma of the Head and Neck Mucosa: A Neoplasm Closely Resembling Microcystic Adnexal Carcinoma

“…Microcystic adnexal carcinoma (MAC) is a rare neoplasm that most often arises in the central facial skin of middleaged and older adults [1][2][3][4][5][6]. It is most common among Caucasians and shows a slight female predominance.…”

“…This infiltrative pattern corresponds with their clinical behavior: MACs characteristically show extensive invasion and local destruction and are prone to recurrence. This insidious, locally-aggressive course necessitates lifetime monitoring for and management of recurrence even after resection and therapy [1][2][3][4][5][6].…”