Answer to Case 678

 Answer to the Parasite Case of the Week 678: Sparganosis - infection with the larval form (sparganum) of Spirometra sp.  Kudos to Dr. Francisco Bravo for getting the correct answer, and for the nice description from Florida Fan.

This was a fascinating case as sparganosis is a relatively rare parasitic infection in humans, and the way it was discovered following fine needle aspiration is very unique. It's possible that the laminated calcification seen on the aspirate smear is a calcareous corpuscle, but it's hard to know for sure. Therefore, it was a good thing that the sparganum began to extrude from the aspirate site and could be removed. It's macroscopic and microscopic appearance are diagnostic. Note the longitudinal smooth muscle fibers, loose stroma, and numerous calcareous corpuscles. The latter are seen in all cestodes, in both larval and adult forms. In this case, they mostly appear as empty oval-shaped structures, but can also calcify and appear dark purple on routine H&E stain.

Although removal is curative, this patient should be counseled to avoid eating undercooked fish, reptiles and frogs, to avoid acquiring another case of sparganosis in the future!