Case #191 – November, 2006

DPDx Telediagnosis Assistance received a request for confirmation of an identification by the Vermont Department of Health Laboratory. Figures A and B show an object that was extracted from a chest wound of a patient. The object measured 7mm. The patient’s travel history was unknown. What is your diagnosis? Based on what criteria?

Figure A

Figure B

This is a case of cutaneous myiasis caused by a bot fly larva, possibly in the genus Gasterophilus. Based on the presence of only two spiracular slits, this was a second instar larva, making identification more difficult. Species determination does not affect treatment. Diagnostic features were:

the presence and arrangement of cuticular spines, which are often seen in bot fly larvae.
the appearance of spiracular slits, which was also consistent with some species of bot fly larvae (especially Gasterophilus).