Endocrine Abstracts

Case history: An 18-year old lady being investigated for anaemia, was incidentally found to have a 15 cm left adrenal mass. History taking revealed a 6-month history of weight gain, fatigue, and hirsutism. Past medical history was positive for mental illness. There was no learning disability or history of epilepsy. Physical examination was unremarkable.

Investigations: Biochemical work-up for a functional adenoma revealed normal serum cortisol and circadian rhythm, normal plasma metanephrines and normal adrenal androgens. A CT scan of the abdomen showed a well-defined, vascular, left suprarenal mass, measuring 11 cm. The mass had heterogeneous enhancement, with areas of necrosis. There was no evidence of direct invasion and no lymphadenopathy. The lesion was not MIBG avid.

Results and treatment: The patient underwent open left adrenalectomy. Macroscopically, the lesion was well-circumscribed, within the adrenal gland, weighing 450 g. The surface was heterogenous with solid and cystic areas. Microscopically, the tumour was encased in a thick fibrous capsule. There was no evidence of capsular invasion or invasion into the surrounding tissue. Diffuse sheets of epithelioid tumour cells were visible, with very distinct cell borders, abundant eosinophilic cytoplasm and variable amounts of cytoplasmic clearing. Prominent nuclear pleomorphism was appreciated, with evidence of multinucleation.There was no evidence of tumour necrosis and no mitotic figures. Immunohistochemical staining was negative for Chromogranin, Synaptophysin, S100, Calretinin and Inhibin. The tumour, stained positive for MelanA, HMB45 and SMA. Based on these findings, a diagnosis of a Perivascular Epithelioid Cell Tumour (PEComa) was made.

Conclusions and points for discussion: PEComas may occur at various visceral and soft tissue sites. Renal PEComas constitute the majority of cases. Very few adrenal PEComas have been reported in the literature. While most lesions follow a benign course, 33% of PEComas exhibit malignant behaviour. Lesions >4 cm carry a higher risk for fatal haemorrhage. Benign tumours can be managed conservatively. Surgery should be considered for indeterminate tumours, based on size and previous haemorrhage. Genetically, 27% of PEComas have been linked to the tuberous sclerosis genes TSC-1 and TSC-2. Gene identification has led to advances in the therapy of malignant PEComas, allowing us to target specific metabolic pathways. In particular, future studies are aimed at identifying a possible role for mTOR inhibitors in the treatment of this rare tumor. At 9 months post-surgery our patient remains disease-free. There were no features in the history or physical examination to suggest tuberous sclerosis, hence genetic testing was not performed in this instance.