• Immunoperoxidase stain for low molecular weight keratin shows positivity of the lining cells indicating that the tumor is epithelial rather than endothelial.

• In this case immunoperoxidase stains for factor VIII and CD34 were negative.

•Unknown.

•Unknown. The tumor is believed to be mesothelial in origin.

•Males, mean age is 36 years.

•Adenomatoid tumors may be noted by the patient or physician as a non-painful nodule of the testis.
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•The majority of epididymal adenomatoid tumors are less than 2 cm in diameter and are attached to the surface of the epididymis.

•The tumors appear solid and tan on cut surface.

•Histologically the tumor shows an epithelioid component appearing as strands and cords and defines gland-like or vascular-like spaces.

•The cells may have a flattened appearance or may appear cuboidal.

•On immunoperoxidase stains these cells are keratin positive and negative for factor VIII and CD34.

•Electron microscopy shows abundant long delicate microvilli on the luminal surface of the tumor cells.

•Adenomatoid tumors are believed to be basically benign mesotheliomas.

•Urological Pathology. Murphy WM (ed). Philadelphia: Saunders, 1989, pp. 367.

• Current literature from PubMed at National Library of Medicine