Case #493 – June, 2019

A 36-year-old male returning from a 3-month stay in rural China sought medical attention for a tender, slowly migrating nodule that had developed on his abdomen. The subcutaneous mass was excised in the clinic; a motile, ribbon-like object approximately 5 cm long was found within. The organism was placed into 10% formalin and submitted to the DPDx Team for identification. The gross morphology of the organism is shown in Figures A and B; Figure C shows the internal structure after exposure to lactophenol (100x magnification).

What is your diagnosis? Based on what features?

Figure A

Figure B

Figure C

This was a case of subcutaneous sparganosis caused by migrating plerocercoid larvae (spargana) of some species of the cestode Spirometra. Diagnostic morphologic features shown were:

a flat, white, wrinkled appearance without true segmentation
a clefted anterior end, representing a developing scolex (Figure A, arrow)
the presence of calcareous corpuscles (Figure C, arrows)

Figure A

Figure C

Spargana have been recovered from many anatomic sites such as the eyes, subcutaneous tissue, and central nervous system. Identification to the species level is not possible based on morphology of the spargana and is usually not warranted in clinical practice, but can be achieved through molecular methods.

More on sparganosis: https://www.cdc.gov/dpdx/sparganosis/index.html

Images presented in the dpdx case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.

DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.