A 61 year-old female presents with a persistent right finger infection. The infection started as a painful small wound at the tip of her finger 3 weeks ago. She was prescribed acyclovir and doxycycline, but was unable to take the doxycycline do to abdominal pain. AP and lateral radipgraphs (figures 1 and 2) show erosive changes to the distal interphalangeal joint consistent with possible osteomyelitis.
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The patient’s diagnosis was originally thought to be herpatic whitlow; however, the infection did not improve on acyclovir. In retrospect, the initial diagnosis was likely a felon which presents much like herpatic whitlow but is caused from a bacterial infection as opposed to viral. Finger infections must be diagnosed appropriately and treated early to avoid comorbidities including osteomyelitis and amputation. The most common types of finger infections include a felon, paronychia, pyogenic flexor tenosynovitis, and herpatic whitlow. A paronychia is an infection of the epidermis bordering the nail and is caused by bacterial entry under the eponychial fold. The infection is commonly seen after manicures or with hangnails. A felon is an infection of the distal phalanx pad, or more specifically, an abscess of the numerous small compartments of the fingertip pulp. A felon is caused by bacterial inoculation during penetrating trauma to the fingertip and is usually more painful than a paronychia. Herpatic whitlow is a viral infection caused by inoculation of herpes simplex virus I or II into broken skin. The infection can be caused by autoinoculation from a person with oral or genital herpes, or can be an occupational hazard for a person exposed to tracheal secretions. The viral infection can develop 2-14 days after exposure. The infection usually starts with redness and vesicles that transition to ulcerations.
Pyogenic flexor tenosynovitis is a bacterial infection of the flexor sheath of the finger. The four Kanavel signs are the hallmark of flexor tenosynovitis and include: 1) Involved finger is resting in a flexed position; 2) Tenderness to palpation of the flexor sheath; 3) Diffuse sausage digit like swelling; and 4) Severe pain with passive finger extension. The most common bacterial cause of a felon, paronychia, and pyogenic flexor tenosynovitis is Staphylococcus aureus. 1, 2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
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- Reid A. Abrams, MD, and Michael J. Botte, MD. Hand Infections: Treatment Recommendations for Specific Types. J Am Acad Orthop Surg. 1996;4:219-230