Case of the Week 303

Dear Readers,
In honor of Mother's Day, I have a special case for you:

A firm nodule measuring approximately 2 cm in diameter was removed from the scalp of  a man from Southern Venezuela.  The following histologic sections show the adult female (mother) worm and her offspring.  In this infection, the adult worms stay in one location while the migrating offspring wreak havoc in the host.  Diagnosis?

Nodule, H&E, 20x total magnification

Cross-sections of the female worm, H&E, 100x

 Female and offspring, H&E, 400x

 H&E, 200x

As a special bonus, here is Blaine's poem a week early:

Some poor mothers, they just can’t seem to win

When your kids are parasites writhing around in the skin

You try to keep them snug down in the uterine tubes

Until a blackfly comes along looking for food

But you must send them off into the world, so the cycle begins.