A 58-year-old man is being evaluated for constipation and weight loss over the last several months. During the past 2 weeks, he has had several episodes of rectal bleeding. The patient has never had a screening colonoscopy. Examination shows a soft and nontender abdomen without masses or organomegaly. Digital rectal examination reveals a firm palpable mass in the rectal vault. Flexible rectosigmoidoscopy shows a large ulcerative mass in the middle third of the rectum extending to the rectosigmoid junction. He undergoes surgical resection of the rectosigmoid colon. Frozen section analysis reveals clear margins of the colon specimen with metastases in the pararectal lymph nodes. Which of the following lymph node groups should be sampled in this patient for further assessment of metastatic disease?

Question

A 58-year-old man is being evaluated for constipation and weight loss over the last several months.  During the past 2 weeks, he has had several episodes of rectal bleeding.  The patient has never had a screening colonoscopy.  Examination shows a soft and nontender abdomen without masses or organomegaly.  Digital rectal examination reveals a firm palpable mass in the rectal vault.  Flexible rectosigmoidoscopy shows a large ulcerative mass in the middle third of the rectum extending to the rectosigmoid junction.  He undergoes surgical resection of the rectosigmoid colon.  Frozen section analysis reveals clear margins of the colon specimen with metastases in the pararectal lymph nodes.  Which of the following lymph node groups should be sampled in this patient for further assessment of metastatic disease?

Quizplus · Accepted Answer

11ec160b_3586_0675_9249_7f92e9a56f68_MD0001_00 Lymphatic drainage of the colon generally follows the arterial supply. Lymph nodes are located on the bowel wall (epicolic nodes), inner bowel margins along the arterial arcades (paracolic nodes), around the corresponding mesenteric vessels (intermediate nodes), and at the origin of the superior and inferior mesenteric arteries (principal nodes). The sentinel lymph nodes (first 1-4 lymph nodes draining a specific colonic segment) are usually the first site for colon cancer metastasis. Lymphatic channels proximal to the anal dentate line drain into the inferior mesenteric and internal iliac lymph nodes. The upper rectum and superior part of the middle rectum follow the superior rectal nodes along the superior rectal artery into the inferior mesenteric lymph nodes. The middle to lower third of the rectum can drain upward into the inferior mesenteric nodes or follow the middle rectal nodes along the middle rectal artery to the internal iliac lymph nodes. Areas distal to the anal dentate line drain primarily into the inguinal nodes, although some lymph can also reach the inferior mesenteric and internal iliac nodes. (Choice A) The celiac lymph nodes are located around the celiac trunk and drain lymph from the gastric, hepatic, and splenic nodes. These in turn drain their respective organ systems (not the colon). (Choice C) The left colic lymph nodes and their branches are located along the left colic artery and drain the left colonic flexure and upper descending colon. (Choice D) The right colic lymph nodes are found along the right colic artery and primarily drain the upper ascending colon. (Choice E) The superficial inguinal lymph nodes lie below the inguinal ligament and are bordered by the sartorius and adductor longus muscles. They drain parts of the genitalia (eg, penis, scrotum, perineum, and vulva), buttocks, anus below the dentate line, and abdominal wall below the umbilicus. (Choice F) The superior mesenteric lymph nodes (mesenteric, ileocolic, and mesocolic) mainly drain the ileum, jejunum, vermiform process, and parts of the ascending and transverse colon. (Choice G) Lymph node metastasis typically occurs sequentially through the epicolic/paracolic, intermediate, and paraaortic lymph nodes. Later in the disease course, the cancer can spread via the thoracic duct to the supraclavicular lymph node (Virchow node). Educational objective: Lymphatic drainage of the rectum proximal to the anal dentate line occurs via the inferior mesenteric and internal iliac lymph nodes. Areas distal to the dentate line drain primarily into the inguinal nodes.

A 58-Year-Old Man Is Being Evaluated for Constipation and Weight