Herpetic whitlow is usually self-limited However, oral acyclovir may be given in the first few days of the infection to shorten the course For the immunocompromised patient, parenteral acyclovir should be considered to prevent dissemination Herpetic whitlow can also be superinfected with bacteria in which case appropriate antibiotic therapy is indicated Felon A felon is a deep infection of the distal pulp space of the fingertip Felons are caused by introduction of bacteria into the pulp space, usually by punctures (which may be trivial) or splinters Causative organisms are similar to those found in eponychial infections A felon typically presents as an exquisitely tender and throbbing fingertip that is swollen, tense, warm, and erythematous Fluctuance may only be appreciated during later stages Felon usually evolves relatively slowly, beginning with mild pain and minimal swelling that progress over days This slow progression is in part caused by the anatomy of the pulp, which consists of multiple closed spaces formed by fibrous septae that connect the volar skin to the periosteum of the distal phalanx Infection is often initially contained within these small compartments With progression of infection, increased pressure may cause local ischemia Complications of felon include osteomyelitis, flexor tenosynovitis, and septic arthritis of the distal interphalangeal (DIP) joint Because the deep septal attachments are distal to the DIP joint and flexor tendon sheath, there is less risk of spread to these structures Treatment of a felon consists of incision, blunt dissection, and drainage Digital blocks are favored for analgesia A longitudinal incision over the area of maximal tension or fluctuance is the procedure of choice If swelling is greatest laterally, an incision along the ulnar surface of the second through fourth digit or radial side of pinky or thumb may be preferred Care should be taken to extend the incision past the DIP joint to prevent formation of a flexion contracture (see Chapter 130 Procedures ) After drainage, a course of oral antibiotics is indicated Close follow-up is essential to monitor for complications A hand specialist should be consulted for patients presenting with fever, lymphangitis, or evidence of osteomyelitis for admission, parenteral antibiotics, and definitive care Subungual Hematoma A subungual hematoma is a collection of blood located under a nail that arises after trauma to the nail bed, typically due to a crush injury Because this mechanism is also a common cause of phalangeal fractures, radiographs are often indicated Patients experience throbbing pain that worsens as more blood collects and pressure increases If the subungual hematoma involves more than 50% of a