Cytopathologic features of pituitary carcinoma with cervical vertebral bone metastasis: a case report

BACKGROUND: Pituitary carcinomas are extremely rare tumors of the adenohypophysis. The presence of craniospinal and/or systemic extracranial metastases is the only reliable criterion for the diagnosis of pituitary carcinoma. To date, only 2 cases have been reported correctly by fine needle aspiration biopsy (FNAB). We present an additional case of pituitary carcinoma with FNAB features. CASE: A 60-year-old woman presented with clinical features of Cushing's disease and a pituitary tumor. She underwent transsphenoidal resection of the tumor. The initial diagnosis was an adrenocorticotrophic hormone (ACTH)-producing invasive pituitary adenoma. The patient presented again with neck pain 6 years after the operation. Magnetic resonance imaging revealed metastatic tumor masses at the level of C5-C6 of the cervical vertebrae. Intraoperative fine needle aspiration and incomplete excision of metastatic tumors were performed. Cytologically, tumor cells were composed of a combination of loose groups and single cells. Neoplastic cells had a relatively monotonous appearance and displayed characteristic neuroendocrine tumor features. Immunocytochemistry from cell block sections revealed AE1/ AE3, synaptophysin chromogranin A and ACTH positivity in the tumor cells. CONCLUSION: Pituitary carcinoma with extracranial systemic metastases demonstrates typical neuroendocrine features on fine needle aspiration. In the differential diagnosis, metastatic neuroendocrine carcinomas should be kept in mind. In the absence of sufficient clinical data, these 2 entities cannot be distinguished correctly through the cytologic features.