Adenomatoid tumor of the adrenal gland: a clinicopathologic study of 3 cases.

Adenomatoid tumors are relatively uncommon benign neoplasms of mesothelial origin, usually occurring in the male and female genital tracts. Rare extragenital adenomatoid tumors have been identified in the adrenal glands, heart, mesentery, pleura, and lymph nodes. In the adrenal gland, adenomatoid tumors may pose a diagnostic challenge. The differential diagnosis includes adrenocortical carcinoma and metastatic carcinoma, especially signet ring cell carcinoma. Because of its glandular pattern, an adenomatoid tumor may be confused with an adenocarcinoma. We present 3 cases of adrenal adenomatoid tumors, including one with a concurrent large hemorrhagic vascular adrenal cyst. The adenomatoid tumors were unilateral, appeared solid and white, and varied from 1.7 to 4.2 cm in diameter. They occurred in 3 male patients aged 33, 33, and 46 years. One patient presented with abdominal pain due to the presence of a concurrent large adrenal cyst. The tumor was an incidental radiological finding in another case and was discovered during the course of a workup for hypertension in the third case. The light microscopic appearances were consistent with those of typical adenomatoid tumors. Immunohistochemical stains for calretinin and cytokeratin 5/6 were positive, confirming the tumors' mesothelial origin. Ultrastructural studies performed in 2 cases revealed microvilli and desmosomes. Follow-up showed no evidence of recurrence or metastasis. In our experience, the key to the diagnosis of this rare benign tumor is to consider adenomatoid tumor in the differential diagnosis of any glandular tumor occurring in the adrenal gland.