Neuroendocrine Small Cell Carcinoma of the Colon in a Young Man With Autosomal Recessive Polycystic Kidney Disease

Abstract

Introduction: Small Cell Carcinoma (SmCC) of the colon is a rare but aggressive neoplasm. Previously, it has been reported in the middle aged and the elderly. Here, to the best of our knowledge, we report the case of one of the youngest adults with primary SmCC of the Colon and the first one with concomitant diagnosis of Autosomal Recessive Polycystic Kidney Disease (ARPKD). Case description: This is the case of a 24 year old Caucasian man with ARPKD status post kidney transplant and Chronic Antibody-Mediated Rejection (AMR) on monthly IVIG treatment who presented with rectal bleeding for 1 week associated with constipation and abdominal pain. Physical exam was consistent with severe conjunctival pallor. Lab work showed anemia with hemoglobin of 6.2 g/dL. Colonoscopy revealed a large ulcerated mass at the hepatic flexure. Staging CAT scans and MRI showed hepatic metastases. Histopathology confirmed poorly differentiated Neuroendocrine SmCC with lympho-vascular invasion and tumor cells positive for Cytokeratin, Chromogranin, CD56 and TTF-1. Right hemicolectomy was performed and chemotherapy with Etoposide and Carboplatin was initiated. Disease course was complicated by septic shock secondary to perforated hollow viscus requiring emergent laparotomy and surgical repair. Thereafter, he was discharged in a stable condition and is now due for his third cycle of chemotherapy, about 4 months from the time of initial diagnosis. Discussion: SmCC of the colon has an incidence of less than 1% among colorectal cancers. At the time of diagnosis, it is common to find metastases with a 3-year survival rate less than 15%. Although, immunosuppression and ARPKD gene, PKHD1, have been implicated in an increased risk of colorectal adenocarcinomas, there is scant evidence correlating colorectal SmCC with such risk factors. American Society of Transplantation recommends annual FOBT and sigmoidoscopy every 5 years in renal transplant recipients from the age of 50 years with no recommendation to begin screening at an earlier age. Hence, it is important to identify potential associations to develop preventive strategies to reduce mortality from GI malignancies post transplant. We believe, this case report may provide a sense of clinical vigilance and research direction to facilitate the identification of key factors in the pathogenesis of this rare but fatal entity. Furthermore, it may provide supporting evidence for revising screening recommendations for high risk individuals.Figure 1Figure 2Figure 3