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NBME 23 Answers

nbme23/Block 2/Question#23

A 75-year-old man with prostate cancer has ...

Prostatic venous plexus to the vertebral venous plexus

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  1. Cancers of the pelvis, including the prostate, spread to the lumbosacral spine via the vertebral venous plexus (VVP).

    • The VVP communicates with a number of venous networks, including the prostatic venous plexus, which receives the venous supply from the prostate, penis, and bladder.

    • VVP runs up the entire spinal column and connects with the venous supply of the brain via a valveless system (Batson’s Plexus) which allows for bidirectional flow and regulation of intracranial pressure.This venous connection to the cerebral circulation may help explain the propensity of tumors to metastasize to the brain.

  2. The VVP also communicates with the azygos vein in the chest, which explains in part why breast and lung cancers frequently metastasize to the thoracic spine.

    • Similarly, due to pulmonary venous drainage into the left side of the heart, lung tumors often spread systemically via the arterial system.
  3. Although lymph nodes are the most common sites of metastasis in general, lymphatic spread to the skeletal system is very rare.

  4. The pampiniform plexus receives venous drainage from the testis, epididymis, and ductus deferens and drains into the testicular veins.





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submitted by d_holles(41),

Lesson learned -- the NBME doesn't play tricks. If it looks right, it is right.





3. Cancers of the pelvis, including the prostate, spread to the lumbosacral spine via the vertebral venous plexus(VVP).  a. The VVP communicates with a number of venous networks, i. including the prostatic venous plexus, which receives the venous supply from the prostate, penis, and bladder.  b. VVP runs up the entire spinal column and connects with the venous supply of the brain via a valveless system (Batson's Plexus) i. which allows for bidirectional flow and regulation of intracranial pressure.  ii. This venous connection to the cerebral circulation may help explain the propensity of tumors to metastasize to the brain. 4. The VVP also communicates with the azygos vein in the chest, which explains in part why breast and lung cancers frequently metastasize to the thoracic spine.  a. Similarly, due to pulmonary venous drainage into the left side of the heart, lung tumors often spread systemically via the arterial system. 5. Although lymph nodes are the most common sites of metastasis in general, lymphatic spread to the skeletal system is very rare. 6. The pampiniform plexus receives venous drainage from the testis, epididymis, and ductus deferens and drains into the testicular veins.