ABSTRACT
This chapter discusses the histopathology and differential diagnosis of some of infections and infestations affecting the nail, such as viral infections, bacterial infections, mycobacterial infections, treponemal diseases, mycoses of the nail apparatus, protothecosis, protozoal infections, scabies, tungiasis, myiasis, cutaneous larva migrans and pediculosis. Although herpes zoster may involve the limbs, the vesicle groups rarely extend to the tip of the digits and the nail apparatus. Juvenile plane warts do not occur in the nail region; however, epidermodysplasia verruciformis (EDV) may cause histologically similar changes. Epithelioma cuniculatum is a variant of verrucous carcinoma and may occur under the nail. In staphylococcal scalded syndrome, periungual skin and subungual structures may be involved and lead to complete nail loss. Although occurring on the toes, nail involvement of erysipelas is rare. Pseudomonas may both colonize and infect the nail organ. Tuberculosis of the nail apparatus is a rare event in the United States and Europe.
