Cystic lymphangioma-like adenomatoid tumor of the adrenal gland: Case presentation and review of the literature.

Adenomatoid tumors (AT) are usually found in the genital tract of both sexes. They are very rarely located in extragenital sites, and are exceedingly rare in the adrenal. AT of the adrenal gland (AT-AG) are nonfunctioning, usually discovered incidentally and confused on imaging with other more common adrenal neoplasms. The overwhelming majority occur in males. Thirty-four cases have been reported so far, more often presenting grossly as solid tumors, rarely as solid with cystic areas, and 5 cases were almost entirely cystic. At histology they can be either circumscribed or locally infiltrative, and may pose diagnostic difficulties when the pathologist relies on morphology alone or is challenged on frozen section. On light microscopy the diagnosis may be very difficult if the tumor is rich in vacuolated cells, mimicking metastatic signet ring-cell adenocarcinoma. Immunophenotyping and/or electron microscopy are paramount in helping to ascertain their mesothelial lineage. Lymphangioma is the main histologic mimic of solid-cystic and cystic AT-AG, but lymphangioma is immunopositive for endothelial markers and negative for cytokeratins and mesothelial markers. Ultrastructural analysis has been performed in 10 published cases of AT-AG, in all of which the classical microvilli of coelomic type were always observed. In brief we report herein the sixth case of cystic lymphangioma-like AT, which was incidentally discovered during clinical follow-up in a 39-year-old man undergoing cancer staging and surveillance after surgery. The adrenal tumor was 5.5 cm in size and was fully investigated immunohistochemically and ultrastructurally. A complete review of the literature is also presented.