to coalesce and their contents become pustular at which point it can be confused for a paronychia ( Fig 120.2 ) Subsequently, ulceration and crusting occur Most cases occur in children younger than years The process initially results from inoculation of HSV into a small break in the skin Sources of HSV inoculation include finger sucking in children with concurrent herpes gingivostomatitis or by parents with herpes labialis With primary infection, fever and regional adenopathy are often seen With recurrences, these findings are usually absent Unlike paronychia, Gram stain and culture of pustular fluid is negative for bacteria Testing the lesion for HSV is warranted Direct immunofluorescence assay (DFA) and polymerase chain reaction (PCR) are used most commonly When available, a Tzanck smear showing multinucleated giant cells can confirm the diagnosis in real-time, although such testing is less frequently performed A positive HSV culture can be diagnostic when other tests are negative or equivocal FIGURE 120.2 Herpetic whitlow (Reprinted with permission from Fleisher GR, Ludwig W, Baskin MN Atlas of Pediatric Emergency Medicine Philadelphia, PA: Lippincott Williams & Wilkins; 2004.)