Ovarian Thecal Metaplasia of the Adrenal Gland: A Contemporary Case Series With Immunohistochemistry.

This article focuses on ovarian thecal metaplasia (OTM), a rare spindle cell lesion of the adrenal gland predominantly found in women, especially postmenopausal. The authors present the largest recent case series of five female patients aged 42 to 80 with OTM identified incidentally in adrenalectomy specimens removed for various tumors, including renal cell carcinoma, adrenal cortical adenoma, and pheochromocytoma. Histologically, OTM appears as basophilic spindle cell nodules with hyalinized collagen adjacent to or continuous with the adrenal capsule, expressing markers such as desmin, HHF35 (ACTA1), inhibin alpha (INHA), SF1, and WT1, which aid in distinguishing it from other adrenal or renal spindle cell lesions. The pathogenesis remains unclear but may relate to adrenal-gonadal embryological links and hormonal changes in women. Awareness of OTM’s characteristic morphology and immunoprofile is important to avoid misdiagnosis as malignancy.