Rectal carcinoma with dual differentiation toward enteroblastic and neuroendocrine features arising in a patient with ulcerative colitis: a case report

Background Colorectal carcinoma with enteroblastic differentiation is a rare subtype of colorectal carcinomas expressing at least one characteristic immunohistochemical marker among α -fetoprotein, glypican-3, and spalt-like transcription factor 4. On the other hand, colorectal carcinoma with neuroendocrine differentiation is also a unique subtype of colorectal carcinomas showing expression of at least one distinctive marker among chromogranin A, synaptophysin, and CD56. Case presentation We experienced an extremely rare case of rectal carcinoma with dual differentiation toward enteroblastic and neuroendocrine features in a 53-year-old male patient with long-standing ulcerative colitis (UC). Most of the tumor cells were positive for enteroblastic differentiation markers and approximately a half of them for neuroendocrine differentiation markers. Some tumor cells showed only enteroblastic differentiation, and some did only neuroendocrine feature, but some showed both enteroblastic and neuroendocrine differentiation. Conclusion Colorectal carcinoma with dual differentiation toward enteroblastic and neuroendocrine features has not been reported yet. Neoplastic transformation from pluripotent stem cells in dysplastic epithelium of long-standing UC patients may be associated with such dual differentiation features.