Unusual neuroma of the adrenal medulla mimicking schwannoma and coexisting with an adrenocortical adenoma

AbstractAdrenal tumors that are found incidentally during radiological and/or histological examinations performed for unrelated symptoms are called incidentalomas. We report an extremely rare case of incidentaloma in the adrenal medulla that was pathologically detected in an adrenal gland resected for cortical adenoma. The tumor in the medulla, measuring 5 mm in diameter, consisted of interlacing fascicles of Schwann cells and resembled a schwannoma. However, the tumor exhibited a very irregular contour and contained abundant nerve fiber bundles, which were positively immunostained for neurofilament protein, leading to the final diagnosis of neuroma. Although neural hypertrophy is rarely seen in the adrenal medulla, neuroma of the adrenal medulla has not been reported. We demonstrated that some of the axons present in the tumor were positive for tyrosine hydroxylase, indicating that the tumor involved post-synaptic adrenergic neurons. The co-occurrence of medullary neuroma and cortical adenoma is also a novel finding.