Microcystic Adnexal Carcinoma


MAC on Cheek
Clinical photograph of microcystic adnexal carcinoma (MAC) on the cheek of a middle-aged woman shows a flesh-colored papular to plaque-like lesion.



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MAC at Low Magnification
Scanning magnification of a microcystic adnexal carcinoma shows a diffusely infiltrative neoplasm in the dermis and extending into the dermal-subcutaneous interface image.

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MAC at Higher Magnification
Higher magnification of the deep area of MAC shows infiltrative tumor nests image and cords invading into the subcutaneous adipose tissue.

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Perineural Invasion in MAC
High magnification of a deep area of MAC shows tumor cell aggregates closely approaching a nerve image.


TERMINOLOGY


Abbreviations




• Microcystic adnexal carcinoma (MAC)


Synonyms




• Sclerosing sweat duct carcinoma

• Syringoid carcinoma, malignant syringoma (older terms, should be avoided)


Definitions




• Low-grade malignant adnexal tumor with follicular and ductal differentiation


ETIOLOGY/PATHOGENESIS


Environmental Exposure




• Some cases may be related to solar damage (UV radiation) or radiation therapy
image Higher incidence reported on left side of face, which receives greater solar exposure during driving


Unknown




• Most cases


CLINICAL ISSUES


Epidemiology




• Incidence
image Uncommon adnexal tumors

• Age
image Usually occur in middle-aged to older adults

• Sex
image Slightly greater in females


Site




• Most common on face
image Upper lip is most common site

• Can also occur on scalp, trunk, extremities, axillae, and groin


Presentation




• Indurated, plaque-like, or nodular lesion


Treatment




• Surgical approaches
image Complete excision with clear margins

image Mohs excision is effective and likely optimal approach in most cases

• Adjuvant therapy
image Reports of effectiveness with adjuvant radiotherapy


Prognosis




• High incidence of local recurrence (up to 50%), but only very rare metastases
image Metastases have been reported to local lymph nodes, but may represent local, deep invasion, rather than true metastasis


MACROSCOPIC


Size




• Typically measure > 1 cm in diameter


MICROSCOPIC


Histologic Features




• Bland-appearing, dermal-based adnexal tumor
• Deeply invasive and not well circumscribed

• Perineural invasion often present in deeper areas

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Microcystic Adnexal Carcinoma
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