Mixed adenoneuroendocrine carcinoma with brain metastasis

Abstract

Objective To study clinicopathological features, diagnosis, differential diagnosis and prognosis of mixed adenoneuroendocrine carcinoma (MANEC).  Methods One case of MANEC with brain metastasis was reported focusing on the following aspects: clinical manifestations, histopathological features and immunophenotypes, and the relevant literatures were reviewed.  Results A 35-year-old male presented headache and vomiting, and his head CT scan showed a lesion located in the right temporal lobe. The tumor was detected after separating the cerebral cortex during the surgery. The tumor diameter was 3 cm. The tumor was soft and rubbery with ill-defined margins, and rich in blood supply. Under optical microscopy, the tumor was consisted of small round cells of the same size, with focal tumor cells arranged around blood vessels in a pseudorosette manner or papillary manner with brisk mitotic activity. The boundary between tumor and brain tissue was ill-defined. By using immunohistochemical staining, the tumor cells were diffusely positive for synaptophysin (Syn) and CD56, and negative for glial fibrillary acidic protein (GFAP), pan cytokeratin (PCK), CD3, CD20, vimentin (Vim), leukocyte common antigen (LCA), thyroid transcription factor-1 (TTF-1), S-100 protein (S-100), neurofilament (NF), nestin (Nes), CK5/6, CK8/18 and CD99. Ki-67 labeling index was about 62%. Sigmoidoscopy was performed later in another hospital and showed a mass in the patient's colon. The colon tumor was biphasic in appearance, and was consisted of two distinct components: isomorphic small round cells and low-middle differentiated adenocarcinoma cells. The small round tumor cells were diffusely positive for Syn and CD56, and negative for PCK. The adenocarcinoma cells showed opposite results.  Conclusions MANEC is a rare tumor, which is defined in 2010 by WHO Classification of Digestive, and to the best of our knowledge, MANEC of the colon with brain metastasis has never been described. Therefore, this paper reports the first case of MANEC of the colon with brain metastasis. Definite diagnosis could be made by medical history, typical histopathological characteristics and immunohistochemical expressions.

DOI: 10.3969/j.issn.1672-6731.2015.05.010