Gastric endocrine cell hyperplasia after neoadjuvant therapy for poorly cohesive carcinoma: a diagnostic pitfall

Mucosal endocrine cell hyperplasia is a poorly described phenomenon that may occur following neoadjuvant therapy in variety of gastrointestinal cancers. We describe two cases cohesive gastric carcinoma which underwent chemotherapy. Subsequent biopsy and resection showed the presence cells occurring singly micronests within deep lamina propria, showing typical reactivity with synaptophysin chromogranin. The distribution these cytokeratin positivity mimic residual carcinoma, particularly small post-therapy biopsies. This thought to be related normal mucosal elements being rendered relatively conspicuous by depletion malignant good response. treacherous finding misdiagnosed on biopsies as malignancy, leading potentially avoidable differences subsequent management. error avoided awareness this applying simple panel directed immunohistochemical markers, coupled morphological correlation. Endocrine post disease result false-positive interpretation disease. Interpretation post-treatment should take into account avoid potential clinically significant diagnostic pitfall.