Extramedullary plasmacytoma in the adrenal incidentaloma

High-resolution imaging has led to the increasingly frequent discovery of adrenal incidentalomas. Most are nonfunctioning tumours and adenomas, but it is difficult to distinguish benign from malignant tumours using only morphological and laboratory data, and the diagnosis often remains uncertain without histological examination. Here we report the case of a 52-year-old Japanese man who had a right adrenal incidentaloma 4 cm in diameter. The tumour was removed by laparoscopic adrenalectomy. The pathology specimen revealed the typical histology of plasmacytoma. Extramedullary plasmacytoma is a very rare type of plasma cell proliferative disorder. This is the first documented case of an extramedullary plasmacytoma in the adrenal gland.