A Rare Adrenal Incidentaloma: Adrenal Schwannoma
A 32-year-old female presented with new onset of intermittent right flank pain. During examination, a left adrenal mass was found incidentally on abdominal ultrasonography and she was referred to our institution for additional evaluation. Her medical and family histories were unremarkable. On physical examination the abdomen was soft, blood pressure was 130/85 mm Hg and pulse rate was 72 beats/min; sinus rhythm was normal. Blood count and biochemistry analysis were within normal limits.\nA heterogeneously enhancing soft tissue mass on the medial aspect of the left adrenal gland measuring 65 × 95 mm was visualized and no additional mesenteric or retroperitoneal lymphadenopathy was identified on the abdominal CT scans. As the mass was approximately 10 cm in size, [18F] fluorodeoxyglucose (18FDG) PET-CT was also performed. It showed intense uptake within the left adrenal nodule with a standardized uptake value (SUVmax) of 9.5, indicative of malignancy (fig. ). Endocrinological examinations including serum electrolytes, cortisol, urinary metanephrine, normetanephrine, adrenalin, noradrenalin and vanillyl mandelic acid, as well as plasma renin and aldosterone were within normal range. Also, a dexamethasone suppression test showed values within the normal range at onset and at 30 min. Due to the large size of the tumor, standard transperitoneal adrenalectomy was performed without complications. Postoperative pathological evaluation revealed schwannoma in the adrenal gland, a hard, well-circumscribed, encapsulated mass 4 × 8 × 10 cm in overall dimensions that was grossly compressing the adrenal parenchyma. Histologically, the tumor consisted of spindle cells with alternating areas of compact hypercellularity with irregular streams and without atypia or mitosis. Immunohistochemical analysis demonstrated rare Ki67-positive cells (<5%) while SMA, desmin, CD34 and CD117 staining was negative in tumor cells. In contrast to these results, S-100 and vimentin staining were diffusely positive across the tumor. Thus, the evidences corresponded to a benign adrenal schwannoma type Antoni A (fig. , fig. , fig. , fig. ). The patient was discharged uneventfully on the sixth day after surgery.