Endocrine Abstracts

Introduction: Adrenal schwannomas are rare but important causes of adrenal tumours which can often only be diagnosed histologically. We present an interesting case of an incidentally detected adrenal schwannoma.

Case: A 67-year-old gentleman had an ultrasound imaging of the abdomen that incidentally revealed a large right adrenal mass prompting referral to the endocrinology service. His past medical history included myocardial infarction and hypertension. There were no clinical features suggestive of hormonal excess and his blood pressure was well controlled on medications. CT scan revealed a 15cm cystic lesion that was heterogenous in appearance not invading any adjacent structures, although the images suggested some pressure effects on the bowel and kidney. Endocrine tests confirmed non-functional status. FDG PET scan was undertaken in view of the lesion size and characteristics, and it confirmed the cystic swelling with foci of calcification. There was heterogenous moderate activity (SUV max up to 6.2) in the solid components, mimicking malignancy.

Management: Open right adrenalectomy was performed, and post-op recovery was uneventful. Histopathology revealed a smooth outer surface, with a calcified capsule. There were areas of Antoni A and B cells, which helped determine schwannoma and the type. Ancient degenerative cystic changes were present as well as cellular polymorphism and nuclear atypia, both of which made it hard to distinguish the tumour from malignancy. Immunohistochemical analysis revealed presence of several markers (S100, p16, SOX10) suggestive of a schwannoma tumour. The tumour also presented with a low proliferation index (ki-67), which also coincides with schwannoma in keeping with previous studies.

Discussion: Adrenal Schwannomas are rare and only around 80 cases have been documented in the literature. Furthermore, a diameter of 15cm makes this tumour one of the largest described. Diagnosis could only be determined after operation following immunohistochemical and histopathological analysis.