A nonfunctional adrenal incidentaloma revealed by intestinal obstruction: metastatic adrenocortical carcinoma diagnosed by surgery.

Summary: This case report describes an 84-year-old male patient who presented with symptoms of intestinal obstruction and was subsequently diagnosed with metastatic adrenocortical carcinoma (ACC), a rare and aggressive endocrine malignancy. The patient arrived at the emergency department with abdominal pain, nausea, vomiting, and bloating. Imaging studies revealed a segmental ileal mass suggestive of obstruction and a large (12 × 8 cm) adrenal mass. Hormonal assays indicated a nonfunctional adrenal incidentaloma. Due to persistent obstruction, the patient underwent surgical resection of the terminal ileum and a left adrenalectomy. Histopathological examination confirmed ACC with metastasis to the small intestine. This rare presentation is notable because ACC typically manifests with hormone excess or mass effect symptoms, and intestinal metastasis causing mechanical obstruction is exceedingly uncommon. Radiologically, the adrenal mass lacked classic features of ACC, contributing to initial diagnostic uncertainty. Postoperatively, the patient recovered uneventfully and was started on mitotane therapy after PET imaging confirmed residual disease and para-aortic lymph node metastasis. This report underscores the importance of thorough evaluation of large adrenal incidentalomas, even if nonfunctional, and highlights intestinal obstruction as a rare but possible initial presentation of metastatic ACC. It contributes to the limited literature documenting atypical clinical manifestations of this rare tumor. Learning points: Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy that is frequently diagnosed at an advanced or metastatic stage. Nonfunctional adrenal incidentalomas ≥4 cm in size warrant comprehensive hormonal evaluation and imaging, followed by multidisciplinary assessment due to the potential risk of malignancy. In this case, despite benign-appearing radiological features, histopathological examination confirmed that the adrenal mass was a metastatic adrenocortical carcinoma. R0 resection remains the only potentially curative treatment for ACC; in selected cases, synchronous resection of metastatic lesions may be necessary. This case highlights a previously undocumented presentation of ACC manifesting as small bowel obstruction due to intestinal metastasis, thereby expanding the clinical spectrum of this rare entity.