Cystic lymphangioma-like adenomatoid tumor of the adrenal gland: report of a rare case and review of the literature.

Adenomatoid tumors (AT) are uncommon, benign tumors of mesothelial origination most frequently encountered in the genital tracts of both sexes. Their occurrences in the extragenital sites are much rarer and could elicit a variety of differential diagnosis both clinically and morphologically. With regard to the adrenal gland, to the best knowledge of us, only 31 cases of AT have been reported in the English literature. Several histologic growth patterns have been documented in AT, among which cystic type is the least common one. We herein present a further case of AT arising in the adrenal of a 62-year-old Chinese man with a medical history for systemic hypertensive disease. The tumor was incidentally identified during routine medical examination. An abdomen computed tomography scan revealed a solitary mass in the right adrenal. Grossly, the poorly-circumscribed mass measured 3.0 x 3.0 x 2.0 cm with a cut surface showing a gelatinous texture with numerous tiny cystic structures. Microscopic examination showed an infiltrated lesion with honeycomb appearance mimicking a lymphangioma, which composed predominantly of variably sized and shaped anastomosing small cystic spaces lined by flattened endothelial-like cells, without any epithelioid or signet-ring like components present. Foci of extraadrenal tumor extension, lymphoid aggregates with occasional germinal centre formation, intralesional fat tissue, stromal myoid proliferation and ossification were also observed. Immunohistochemical analyses confirmed the mesothelial differentiation of this tumor and indicated a diagnosis of cystic lymphangiomatoid AT of the adrenal.