Gastric amphicrine carcinoma: A histopathological diagnostic conundrum

Abstract

Amphicrine carcinoma is rarely reported in literature. It is characterised by dual positivity of neuroendocrine markers and mucin stain in the same cells depicting divergent differentiation. Recently published WorldHealth Organisation (WHO) classification of neuroendocrine neoplasm of 2022 differentiates it from adenocarcinoma and mixed neuroendocrine-nonneuroendocrine neoplasms (MiNEN) it shows varied histomorphology and on rare occasions neuroendocrine features may not be evident in poorly differentiated carcinoma. Hence, diagnosis based solely on histomorphology can be misleading. This is a case of amphicrine carcinoma in an elderly female which showed poorly differentiated morphology along with signet ring cells. Same cells demonstrated immunopositivity for synaptophysin, chromogranin A and were also positive for mucin stains (PAS, PAS-D and Alcian blue). This case report, thus, emphasises the importance of neuroendocrine markers as a part of routine immunohistochemistry in poorly differentiated gastric carcinomas to aid diagnosis of amphicrine carcinoma.