Small cell colorectal cancer: a rare tumour with an aggressive course

A relatively healthy male patient in his 60s presented with chest pain and shortness of breath in addition to a history of significant weight loss over the preceding months. He was admitted to the hospital and investigated with a CT pulmonary angiogram, which did not demonstrate a pulmonary embolus, but he subsequently went on to have an ultrasound and CT scan because of abnormal findings. His CT demonstrated some thickening of the mid-transverse colon, and, in addition, large volume liver metastases described as innumerable and probably replacing most of the liver. Initially, his liver function tests were only mildly deranged at the presentation. Flexible sigmoidoscopy was performed, and a transverse colonic malignancy was identified and biopsied, which demonstrated an extrapulmonary small cell carcinoma (EPSCC). He was admitted for urgent chemotherapy for newly diagnosed metastatic small-cell colonic cancer; he developed tumour lysis syndrome following his first dose of chemotherapy. He continued to decline following this and died soon after his admission. Metastatic small-cell colonic cancer is a rare diagnosis which is challenging to manage due to the lack of trial evidence to drive treatment strategies. The management largely follows the pulmonary small cell cancer pathway. We, therefore, present a colonic EPSCC case outlining the diagnostic and treatment strategies for this disease.