Microcystic adnexal carcinoma C44.L

Rare, malignant, usually well-differentiated, eccrine sweat gland tumor characterized by slow but locally aggressive growth and a high tendency to recur. Histologically, this malignant tumor can easily be confused with benign andext tumors.

Accumulation in the 6th decade of life. However, occurrence is possible in every adult age (from the 3rd decade of life). No sex preference.

Mostly face (75%), especially upper or lower lip, nasolabial folds, forehead, rarely extrafacial.

Slowly growing (often clinically inconspicuous), painless, skin-coloured, glassy to yellowish-reddish, rarely ulcerated, usually flat, firm, smooth lumps. It is also possible for the nodules to appear as rough red to skin-coloured papules or plaque with edges that are difficult to delimit and superficial telangiectasia. The affected skin appears normal, only occasionally atrophic. Paresthesias or pain are rarer. Local infiltrations of fatty tissue, muscles and bones may occur and complicate the clinical picture.

• Tubular structures, horny cysts, ribbon-shaped tumor cell strands. Deeply infiltrating growth of epithelial tumor nests. Penetration of the entire corium with tumor cell strands and small to medium-sized cysts filled with concentrically layered eosinophilic material. No stratum granulosum in the cyst wall. Perineural infiltration in the form of epithelial bands. The tumor cell bands consist of medium-sized, predominantly cuboid cells with blistery, light-colored nuclei and eosinophilic or clear cytoplasm. Moderate pleomorphism. Distinct fibrotic stroma reaction.
• Immunohistology: Cytokeratin and vimentin positive, mostly CEA positive (characteristic of sweat glands).

Clinical:

• Basal cell carcinoma, sclerodermiformes: Largely at the level of the skin, waxy or ivory-coloured, only vaguely distinguishable from the surrounding area, rough, shiny infiltrate plate with telangiectasia. A clear clinical differentiation is not possible. The histological image is diagnostic.
• Carcinoma, spinocellular: Mostly painless, exophytic, skin-coloured, often crusty, coarse humpy, mostly eroded or ulcerated nodules of coarse consistency. The histological picture is diagnostic scar: anamnesis! No size growth; the woody consistency of the microcystic adnexal carcinoma is rather atypical for a scar. Keloids are rather rare in UV-exposed areas.
• Granuloma eosinophilicum faciei: Typically roundish to oval, 0.5-2.0 cm in size, mostly solitary but also several or numerous, slightly raised, firm, symptomless, brown-red, scale-free plaques with dilated follicle orifices. This results in an "orange peel-like" surface aspect; this is missing in microcystic adnexal carcinoma stests.

Histological:

• syringoma:
• desmoplastic trichoepithelioma
• Trichoadenoma.

• Excision with a sufficiently large safety margin (up to 3.0 cm, if possible in the face) and microscopically controlled surgery (MKC) due to the subclinical tumor extensions and the possible deep infiltration. Long follow-up period.
• Alternative: Irradiation with fast electrons. Caution: High recurrence rate!

Remember! In the differential diagnostic evaluation there should be agreement between clinical and histological findings. If the histological substrate " syringoma" does not correlate with the clinical findings (coarse plate-like infiltrate or solid nodules instead of multiple small nodules), the diagnosis "syringoma" must be carefully checked.

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