A 68-year-old man with carcinoma of the prostate develops back pain. Imaging shows osteoblastic metastases in the lumbar vertebral bodies despite no liver or lung deposits. Which venous route explains this pattern of spread?

• A External iliac vein to common femoral circulation
• B Portal vein to the liver and then systemic circulation
• C Inferior mesenteric vein to the splenic vein
• D Valveless vertebral venous plexus communicating with the prostatic venous plexus ✓

Explanation

The prostatic venous plexus drains into the internal iliac veins but also communicates through the valveless Batson vertebral venous plexus. Raised intra-abdominal pressure can drive blood retrogradely up this plexus, seeding tumour cells directly to the lumbar spine and pelvic bones, classically producing sclerotic metastases. The portal route would produce liver deposits first, which their absence rules out.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.