T2 bright, clinically dim: pheochromocytoma with malignant potential and an atypical clinical presentation

Pheochromocytomas are uncommon adrenal tumors originating from chromaffin cells, with certain cases exhibiting malignant characteristics and behavior. Malignancy is defined by the presence of metastases to sites that normally lack chromaffin tissue; histologic features alone are insufficient for diagnosis. While typically symptomatic, some tumors are discovered incidentally and lack the classic catecholamine-related triad. We present the case of a 52-year-old man with a history of hypertension and hyperlipidemia who presented for routine evaluation and only reported intermittent left lower quadrant pain. On CT and MRI, a 7 cm right adrenal mass with central necrosis was identified; post-contrast MRI showed peripheral enhancement suggesting a hypervascular malignancy. Biochemical testing showed elevated plasma metanephrines and an elevated urinary metanephrine fraction on confirmatory testing. The patient underwent a right adrenalectomy, and histopathological examination revealed pheochromocytoma with angiolymphatic invasion, extra-adrenal extension, a PASS score of 13, and a Ki-67 index of 15-20%, indicating aggressive histologic features consistent with malignant potential. Postoperative recovery was unremarkable and follow-up showed no recurrence. This case underscores the diagnostic value of multimodal imaging in pheochromocytoma, especially when clinical symptoms are not apparent.