Adenocarcinoma of the sweat gland of the vulva: light and electron microscopic study.

A sweat gland carcinoma, a rare tumor of the skin which arose in the posterior fourchette in a 53-year-old white woman, was studied by light and electron microscopy. The tumor formed cords or small acini infiltrating into the stroma with foci of Pagetoid appearance. The cells showed poor intercellular cohesions. PAS and mucin strains were negative. Ultrastructurally the tumor cells in the periphery of the acini were firmly attached to the collagenous matrix with a few pseudopodia. A basal lamina was seen in some areas. The cytoplasm was filled with many ribosomes and moderately developed mitochondria. The bundles of microfilaments in the perinuclear zone were characteristic findings in this tumor. The ultrastructure of this tumor confirmed that this was carcinoma of the sweat gland, which closely resembled intraductal carcinoma of the breast.