Bites and infestations present with wide-ranging manifestations, including papules, vesicles, excoriations, and urticarial lesions. Bedbug bites often involve the arms and develop clinical features of prurigo nodularis. A biopsy will demonstrate a wedge-shaped perivascular lymphoid infiltrate with endothelial swelling and eosinophils, suggesting the correct diagnosis.
Cutaneous larva migrans demonstrates an erythematous serpiginous lesion. The worm is located ahead of the advancing border of the lesion, as the cutaneous reaction is a manifestation of a delayed-type immune response to the organism.
Recognition of arthropods of medical importance is critical to allow assessment of the risk of vector-borne disease and guide management. The skin is often affected by ectoparasites as well as endoparasites, and this section of the atlas will provide a guide to identification of the most important organisms.