Case #523 - September, 2020
A 53-year-old woman from Florida presented to a dermatology clinic with a raised, itchy, red rash on her torso that persisted over the past six months and did not respond to topical treatments. She did not report any recent travel outside of the state. Physical examination noted erythematous papular lesions and punch skin biopsies were collected. Figures A and B show histopathological sectioning of the biopsy revealing numerous eosinophils and a cluster of suspicious parasitic structures (15–25 µm in width). What is your diagnosis? Based on which features?
This case and images courtesy of AmeriPath, Fort Myers, Florida.
This is a case of cutaneous larva migrans (CLM) or creeping eruption, most likely caused by migrating zoonotic Ancylostoma larvae (A. braziliense, A. caninum). Defining features include:
- Double lateral alae (Fig. B; black arrow)
- Lack of reproductive structures, indicating an immature stage of development (larval)
- Size is within the 15 -20 µm range for Ancylostoma larvae
- Weakly developed platymyarian muscle cells, few in number (Fig. B; blue arrow).
Note that skin biopsies often fail to demonstrate larvae in cases of creeping eruption, as larvae generally precede the inflammatory tracks and successfully visualizing the parasite is somewhat serendipitous. Diagnosis is usually based on clinical and epidemiological evidence. Characteristics of lesions may vary by hookworm species and host factors; therefore, species cannot be accurately ascertained by clinical findings alone.
More on cutaneous larva migrans: zoonotichookworm
Images presented in the monthly 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/.