A Case Report of Herpetic Whitlow with Positive Kanavel's Cardinal Signs: A Diagnostic and Treatment Difficulty

Herpetic whitlow is an acute viral infection of the hand caused by either herpes simplex virus (HSV) 1 or 2. Its characteristic findings are significant pain and erythema with overlying nonpurulent vesicles. The differential diagnosis includes flexor tenosynovitis. We present a case of recurrent infection of the middle finger in an immunocompetent 19-year-old girl. Multiple painful pustules with tracking cellulitis were partially treated by oral antibiotics. A recurrence with positive Kanavel's signs suggested flexor tenosynovitis at seven months. Her symptoms improved transiently following emergent surgical open flexor sheath exploration and washout however, she required two further washouts; at eleven and thirteen months to improve symptoms. Viral cultures were obtained from the third washout as HSV infection was disclosed from further history taking. These were positive for HSV2. Treatment with acyclovir at thirteen months after presentation led to a complete resolution of her symptoms with no further recurrences to date. This rare case highlights the similarity in presentation between flexor sheath infection and herpetic whitlow which can lead to diagnostic confusion and mismanagement. We emphasise the importance of careful past medical history taking as well as considering herpetic whitlow as a differential diagnosis despite the presence of strongly positive Kanavel's signs.