microcystic adnexal carcinoma

(redirected from malignant syringoma)

microcystic adnexal carcinoma (MAC)

a form of adnexal tumor that often appears on the face as a yellow, indurated plaque with ill-defined margins. The patient experiences fullness, pain, burning, anesthesia, or paresthesia in the area of the lesion.

microcystic adnexal carcinoma

A rare (circa 300 cases in the world literature) malignant skin appendage tumour, usually typed as a low-grade sweat gland carcinoma which occurs on the head and neck, and especially on the central face. It is locally aggressive and invades bone, muscle, blood vessels, cartilage, and nerves, but rarely metastasises. It presents as a clinical lesion averaging 3 cm2, but leaves an average post-surgical defect of 18 cm2, due to occult extension.

Epidemiology
Adults (median age 50; range 10 to 90).

DiffDx
Syringoma, desmoplastic trichoepithelioma, adenosuamous carcinoma, trichoadenoma, morphoeic BCC, metastatic breast carcinoma, small cell carcinoma.

Prognosis
It is locally aggressive, but rarely metastasises.

Aetiology
20–50% of patients have a history of therapeutic radiation with a 30-year average latency; UV light has also been implicated.
 
DiffDx
Desmoplastic trichoepithelioma, syringoma, trichoadenoma.
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