Functional adrenal oncocytoma (incidentaloma): a case report
Tsu-Feng Lin, MD, Ding-Po Lin, MD, Marcelo Chen, MD, Jong-Ming Hsu, MD
Oncocytic neoplasms are most commonly found in the kidney, thyroid and salivary gland. Adrenal oncocytomas are very rare. There is female predominance with a mean age of 46 years. These tumors are more common on the left side (1:2). Most of these tumors are nonfunctional and hence incidentally detected. Here, we report a case of functional adrenal oncocytoma.
A 54-year-old female had past history of Type 2 Diabetes mellitus and Hypertension undermedication control for ten years. She felt gerneral weakness and abdominal discomforts for half year. There were no palpitations, headache, weakness or fatigue, and the physical examination was unremarkable. So she came to our Gastroenterology outpatient department for further survey. Abdominal echo showed a mixed hypoechoic lesion about 5cm at S6-7. The tumor has well margin, echoic ring at the periphery without vascular invasion. Abdominal computed tomography scan was performed after then and it showed a right adrenal mass (6.3x4.8cm in size) with punctate calcification and heterogeneous enhancement. 48 hours low dose dexamethasone suppression test was arranged, and it showed positive. (base line: Cortisol/ACTH: 20.16μg/dL /6.53pg/mL, post dexa: 18.88μg/dL /1.17 pg/mL). Other Hemogram and serum biochemistry were within normal limits, except polycythemia (hemoglobin: 17.7g/dl) that was same as before. The tentative diagnosis is right adrenal incidentaloma with Cushing syndrome. She underwent laparoscopic adrenalectomy. The pathologic report showed a well-encapsulated oncocytoma composed of nesting and trabeculae polygonal cells with abundant granular, eosinophilic cytoplasm. After sugery, she received regular OPD follow up in our hospital without any complication.
Adrenal oncocytic neoplasm is usually a large, benign, nonfunctional adrenal tumor and is found incidentally. Only 17% functional adrenal mass (Cushing, pheochromocytoma, virilizing syndrome). The mainstay of therapy is adrenalectomy, recently performed by laparoscopy. The prognosis is good for benign tumors.