A case of concurrent cancer in a giant rectal villous adenoma that resulted in extensive lymph node metastases

The patient was a 72-year-old man. Colonoscopy revealed a circumferential villous tumor with granular aggregates extending from the rectosigmoid (RS) to the lower rectum (Rb). Although most portions were indicative of a villous adenoma, a reddish coarse region at the upper rectum (Ra) was diagnosed as a concurrent adenocarcinoma based on biopsies. Consequently, we performed laparoscopy-assisted intersphincteric resection (ISR) and D3 lymph node dissection. Pathological diagnosis revealed multiple lymph node (LN) metastases, including ones at the root of the inferior mesenteric artery (IMA). Adjuvant chemotherapy was administered with XELOX. However, computed tomography (CT) and positron emission tomography (PET) conducted 6 months after surgery revealed recurrent LN metastasis in the mesosigmoid ie, extra-regional LN metastasis. Therefore, chemotherapy was reinitiated with a FOLFIRI-based regimen. Metastases were observed in the lateral LNs and the para-aortic LNs 9 months after surgery, and in the left supraclavicular LNs 12 months after surgery. Herein, we report a rare case of cancer concurrent with a giant villous adenoma, which resulted in extensive LN metastases.