A Giant Adenomatoid Tumor of the Adrenal Gland: A Report of a Rare and Interesting Case.

Adenomatoid tumor (AT) is a rare benign mesothelial neoplasm that typically arises in the genital tract. Adrenal involvement is exceptionally uncommon, with fewer than 50 cases reported in the literature. Because of its nonspecific clinical and radiological features, preoperative diagnosis is challenging and malignancy is often suspected. We report the case of a 48-year-old man in whom a left adrenal mass was incidentally discovered during evaluation for renal colic. Hormonal assessment demonstrated a non-functioning adrenal lesion. Computed tomography and magnetic resonance imaging revealed a large, well-circumscribed 12-cm heterogeneous mass with predominant cystic degeneration, thick septations, and intralesional calcifications, raising suspicion of a malignant adrenal neoplasm. The patient underwent open left adrenalectomy. Gross examination showed a well-defined yellowish tumor with extensive cystic changes and calcifications. Histologically, the lesion consisted of anastomosing cystic spaces lined by bland flattened to cuboidal cells, associated with lymphoid aggregates, fibrosis, calcifications, and focal ossification. Immunohistochemistry demonstrated strong positivity for CK7, calretinin, WT1, and D2-40, confirming mesothelial differentiation, while CD31 and CD34 were negative. These findings established the diagnosis of adrenal AT. The postoperative course was uneventful, and no recurrence has been observed during follow-up. Adrenal AT is a rare benign lesion that may mimic malignant adrenal neoplasms, particularly when large and cystic. Histopathological and immunohistochemical examination remains essential for definitive diagnosis. Complete surgical excision is curative and associated with an excellent prognosis.