Diagnostic challenges of endocrine pathology: three cases highlighting potential diagnostic pitfalls in endocrine glands

This article presents three cases illustrating potential diagnostic pitfalls in endocrine gland neoplasms. The first case is of a 69 year old male with a new diagnosis of multiple myeloma along with radiologically detected lung and bilateral adrenal gland masses. Biopsies revealed a poorly differentiated lung adenocarcinoma that was positive for neuroendocrine markers and CD138, which can lead to confusion with a primary pheochromocytoma and plasma cell neoplasm, respectively. The second case presented is of a 62 year old male with a lesion in the right adrenal gland which on histology was revealed to be a metastatic clear cell renal cell carcinoma (ccRCC) that occurred 14 years after resection of the primary. This case highlights that ccRCC metastases can occur many years after the initial excision. The case also highlights the differentials for clear cell tumours of the adrenal glands which includes adrenocortical adenoma. The final case presented is of a 63 year old male with a past history of Merkel cell carcinoma with a large left sided adrenal gland metastasis. Core biopsies revealed a basaloid tumour positive for CK20 and neuroendocrine markers, confirming a diagnosis of metastatic Merkel cell carcinoma. Metastatic Merkel cell carcinoma may be mistaken for pheochromocytoma due to co-expression of neuroendocrine markers and both having a superficial basaloid appearance.