Introduction: CAP polyposis is a benign colorectal process presenting with multiple colorectal polyps with a "CAP" of inflammatory granulation tissue whose etiology has remained largely unknown.
Case: A 24-year-old male presented with a long-standing history of repeated multiple sessile colonic polyps over a period of 17 years.
Results: The numerous polyps showed consistent histologic features of superficial erosion with a surface "CAP" of granulation tissue with minimal submucosa to evaluate over this period. A left hemicolectomy disclosed an extensive vascular malformation.
Conclusion: The underlying vascular malformation may have an etiologic correlation to the overlying CAP polyps in this patient. Future cases may benefit from an evaluation of the underlying submucosa for the presence of possible vascular malformation likely to be missed on superficial polypectomy.
Keywords: CAP polyposis; inflammatory bowel disease; inflammatory granulation tissue; pathophysiology; vascular malformation.