Pelvis/Perineum — MCQs

A 46-year-old woman comes to the physician for a follow-up examination after a Pap smear showed atypical squamous cells. A colposcopy-directed biopsy of the cervix shows evidence of squamous cell carcinoma. The malignant cells from this lesion are most likely to drain into which of the following group of lymph nodes?

Q22

A 75-year-old man comes to the physician because of a 2-month history of intermittent bright red blood in his stool, progressive fatigue, and a 5-kg (11-lb) weight loss. He appears thin and fatigued. Physical examination shows conjunctival pallor. Hemoglobin concentration is 7.5 g/dL and MCV is 77 μm3. Results of fecal occult blood testing are positive. A colonoscopy shows a large, friable mass in the anal canal above the pectinate line. Primary metastasis to which of the following lymph nodes is most likely in this patient?

Q23

A 62-year-old female presents to her primary care physician complaining of bloody stool. She reports several episodes of bloody stools over the past two months as well as a feeling of a mass near her anus. She has one to two non-painful bowel movements per day. She has a history of alcohol abuse and hypertension. Anoscopy reveals engorged vessels. Which of the following vessels most likely drains blood from the affected region?

Pelvis/Perineum US Medical PG Practice Questions and MCQs

Question 21: A 46-year-old woman comes to the physician for a follow-up examination after a Pap smear showed atypical squamous cells. A colposcopy-directed biopsy of the cervix shows evidence of squamous cell carcinoma. The malignant cells from this lesion are most likely to drain into which of the following group of lymph nodes?

A. Left supraclavicular
B. Right supraclavicular
C. Internal iliac (Correct Answer)
D. Inferior mesenteric
E. Superficial inguinal

Explanation: ***Internal iliac*** - The **cervix** is an organ of the **pelvis**, and its primary lymphatic drainage is to the **internal iliac lymph nodes**. - These nodes are located along the **internal iliac artery** and drain structures supplied by its branches, including the cervix and upper vagina. *Left supraclavicular* - **Left supraclavicular lymph node** (Virchow's node) enlargement suggests metastasis from **abdominal** or **pelvic malignancies**, but it indicates a very advanced stage, not the primary drainage. - This typically occurs when cancer cells have spread widely and reached the **thoracic duct** before ascending to the supraclavicular region. *Right supraclavicular* - **Right supraclavicular lymph node** involvement is typically associated with malignancies of the **mediastinum**, **lungs**, or **esophagus**. - It is not a primary drainage site for cervical cancer and would represent distant, advanced metastatic disease. *Inferior mesenteric* - The **inferior mesenteric lymph nodes** primarily drain structures supplied by the **inferior mesenteric artery**, such as the **descending colon**, **sigmoid colon**, and **rectum**. - They are not involved in the direct lymphatic drainage of the cervix. *Superficial inguinal* - The **superficial inguinal lymph nodes** primarily drain the **external genitalia** (vulva, lower vagina), **perineum**, and lower limbs. - While cervical cancer can metastasize to these nodes in advanced stages, they are not the primary, first-order drainage for the cervix itself.

Question 22: A 75-year-old man comes to the physician because of a 2-month history of intermittent bright red blood in his stool, progressive fatigue, and a 5-kg (11-lb) weight loss. He appears thin and fatigued. Physical examination shows conjunctival pallor. Hemoglobin concentration is 7.5 g/dL and MCV is 77 μm3. Results of fecal occult blood testing are positive. A colonoscopy shows a large, friable mass in the anal canal above the pectinate line. Primary metastasis to which of the following lymph nodes is most likely in this patient?

A. External iliac
B. Inferior mesenteric
C. Para-aortic
D. Internal iliac (Correct Answer)
E. Deep inguinal

Explanation: ***Internal iliac*** - Cancers of the **anal canal above the pectinate line** drain primarily to the **internal iliac lymph nodes**. - The superior portion of the anal canal (above the pectinate line) shares lymphatic drainage with the middle and lower rectum, which drains directly to the internal iliac nodes via lymphatics following the middle rectal vessels. - This is the most direct and primary drainage pathway for tumors in this anatomic location. *External iliac* - The external iliac nodes primarily drain organs such as the **bladder, prostate, and lower limb lymphatics**, not the anal canal above the pectinate line. - While they can be involved in advanced disease, they are not the primary drainage site for anal canal carcinoma in this region. *Inferior mesenteric* - The inferior mesenteric lymph nodes primarily drain the **descending colon, sigmoid colon, and upper rectum**. - While the upper rectum does drain to these nodes, tumors specifically located in the **anal canal** (even above the pectinate line) are in a more distal position where **internal iliac drainage predominates** via the middle rectal lymphatics. - Inferior mesenteric nodes would be more relevant for upper rectal lesions rather than anal canal lesions. *Para-aortic* - The para-aortic lymph nodes receive drainage from organs such as the **kidneys, testes/ovaries, and parts of the gastrointestinal tract**, and represent distant nodal stations for anal canal cancers. - Involvement of para-aortic nodes would signify advanced metastatic disease rather than primary regional drainage. *Deep inguinal* - The deep inguinal lymph nodes primarily drain the **anal canal below the pectinate line**, which is derived from ectoderm and drains like other skin structures of the perineum. - The tumor is located **above the pectinate line**, which has visceral lymphatic drainage (via internal iliac nodes), making deep inguinal nodes an unlikely primary site.

Question 23: A 62-year-old female presents to her primary care physician complaining of bloody stool. She reports several episodes of bloody stools over the past two months as well as a feeling of a mass near her anus. She has one to two non-painful bowel movements per day. She has a history of alcohol abuse and hypertension. Anoscopy reveals engorged vessels. Which of the following vessels most likely drains blood from the affected region?

A. Internal pudendal vein
B. Left colic vein
C. Inferior rectal vein (Correct Answer)
D. Middle rectal vein
E. Superior rectal vein

Explanation: ***Inferior rectal vein*** - The patient's symptoms (bloody stool, anal mass, engorged vessels on anoscopy) are classic for **external hemorrhoids**. - **External hemorrhoids** are distended veins located **below the dentate line** in the anal canal, which are drained by the **inferior rectal veins**. - The inferior rectal veins drain into the **internal pudendal vein**, then to the **internal iliac vein** (part of the **systemic venous circulation**). *Internal pudendal vein* - The **internal pudendal vein** drains structures in the perineum and external genitalia, but it is not the **primary/direct drainage** for hemorrhoids. - It receives blood from the inferior rectal veins but is one step removed from the hemorrhoidal plexus itself. *Left colic vein* - The **left colic vein** typically drains the distal transverse colon and descending colon. - It is part of the **inferior mesenteric venous system** and is anatomically distant from the anorectal region, not involved in draining hemorrhoids. *Middle rectal vein* - The **middle rectal vein** drains the middle part of the rectum and connects both portal and systemic circulations. - It drains the **muscularis layer** of the rectum but is not the primary drainage for the external hemorrhoidal plexus below the dentate line. *Superior rectal vein* - The **superior rectal vein** drains the upper part of the rectum and anal canal **above the dentate line**. - Distention of these veins leads to **internal hemorrhoids**, which are typically painless unless prolapsed or thrombosed. - It drains into the **inferior mesenteric vein** (part of the **portal venous circulation**).

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