Swelling and Discoloration of an 8-Year-Old’s Thumb
A previously healthy 8-year-old girl presented to the emergency department with a 3-day history of worsening swelling, pain, and discoloration of the right thumb. The swelling had begun near the fingernail and had progressed toward the base of her thumb. Also noted was a blister on the lateral side of her left thumbnail.
There was no purulent drainage and no history of nail biting, and her fingernails had been cut 2 weeks before presentation. The patient had no recent history of fever or upper respiratory symptoms.
Her father has type 2 diabetes mellitus and also has a history of similar skin changes on his fingers that had resolved with antibiotic therapy.
On physical examination, the girl was afebrile with normal vital signs. Immediately evident was a well demarcated, contiguous, fluid-filled, flaccid bulla that appeared yellow-green in color on the palmar surface, extending from the fingertip to the base of the left first digit at the metacarpophalangeal joint. There was limited flexion at the proximal interphalangeal joint secondary to pain.
A small margin of blanching erythema surrounded each blister. A tense, white periungual bulla, about 1 cm in diameter, was present on the right first digit. Sensation to light touch was intact, and capillary refill was brisk.
There were no other skin changes in her upper and lower extremities, face, or trunk, and no lymphadenopathy.
What explains these symptoms?
A. Herpetic whitlow
B. Pustular dermatosis
C. Insect bite
D. Blistering dactylitis
(Answer and discussion on next page)
Answer: Blistering Dactylitis
A previously healthy 8-year-old girl presented to the emergency department (ED) with a 3-day history of worsening swelling, pain, and discoloration of the right thumb. The swelling had begun near the fingernail and had progressed toward the base of her thumb. Also noted was a blister on the lateral side of her left thumb’s fingernail. There was no purulent drainage and no history of nail biting, and her fingernails had been cut 2 weeks before presentation. There was no history of fever or upper respiratory symptoms. Her father has type 2 diabetes mellitus and had a history of similar skin changes on his fingers that had resolved with antibiotics.
On physical examination, the girl was afebrile with normal vital signs. Immediately evident was a well demarcated, contiguous, fluid-filled, flaccid bulla that appeared yellow-green in color on the palmar surface, extending from the fingertip to the base of the left first digit at the metacarpophalangeal joint. There was limited flexion at the proximal interphalangeal joint secondary to pain. A small margin of blanching erythema surrounded each blister. A tense, white periungual bulla, about 1 cm in diameter, was present on the right first digit. Sensation to light touch was intact, and capillary refill was brisk. There were no other skin changes in her upper and lower extremities, face and trunk, and no lymphadenopathy.
She was admitted to the hospital for intravenous antibiotics and incision and drainage of the wound. Initial antimicrobial management included clindamycin and piperacillin-tobramycin. Wound culture grew many group A β-hemolytic streptococci (Streptococcus pyogenes) and Staphylococcus aureus, so antimicrobial coverage was changed to clindamycin. No methicillin-resistant S aureus species were isolated from the axilla. Results of a complete blood count with differential and the C-reactive protein level were within normal limits.
Clinical presentation and bacterial culture led to a diagnosis of blistering dactylitis. The patient remained clinically stable and was discharged home after 3 days to complete a 7-day course of clindamycin.
Blistering dactylitis is a superficial, soft tissue infection that usually involves the anterior fat pads of the distal portions of the fingers, but also may extend to the proximal and lateral nail fold. Index fingers and thumbs typically are involved, although toe involvement has been reported.1
Blistering dactylitis is characterized by bullae on erythematous bases that can evolve into erosions. Originally described in 1972 by Hays and Mullard,2 blistering dactylitis is linked predominantly to streptococcal infection,2,3 although staphylococcal infections also can occur.1 S pyogenes and S aureus have been the most implicated species. One case of coinfection with herpes simplex virus has been reported.4 The disease may be secondary to an underlying infection in the nasopharynx, conjunctiva, or anus, which results in a need for systemic antibiotic therapy. Multiple bullae on different digits may occur, which should raise suspicion for S aureus infection.5
The lesions usually are not pruritic, burning, or painful, despite their appearance. The disease typically affects school-aged children between 2 and 16 years old.1
The results of a bacterial culture are required to confirm the blistering dactylitis diagnosis. The differential diagnosis includes herpetic whitlow, bullous impetigo, insect bites, acral psoriasis, dyshidrotic eczema, allergic contact dermatitis, irritant dermatitis, pustular dermatosis of the hands, paronychia, foreign-body reactions, and friction, chemical or thermal injuries. Treatment involves incision and drainage of bullae, wet-to-dry compresses for wound healing, and β-lactamase-resistant antibiotics, usually a 10-day course, due to the association with penicillin-resistant S aureus.
Blistering dactylitis is associated with low morbidity and few treatment failures, unless it occurs in immunocompromised patients.6
Henry Wu, MD, is a pediatric resident at Children’s Hospital Los Angeles, Keck School of Medicine of the University of Southern California.
Ara Festekjian, MD, MS, is an assistant professor of clinical pediatrics in the Department of Pediatrics, Division of Emergency Medicine and Transport, at Children’s Hospital Los Angeles, Keck School of Medicine of the University of Southern California.
REFERENCES
1. Fretzayas A, Moustaki M, Tsagris V, Brozou T, Nicolaidou P. MRSA blistering distal dactylitis and review of reported cases. Pediatr Dermatol. 2011;28(4):433-435.
2. Hays GC, Mullard JE. Can nasal bacterial flora be predicted from clinical findings? Pediatrics. 1972;49(4):596-599.
3. Hays GC, Mullard JE. Blistering distal dactylitis: a clinically recognizable streptococcal infection. Pediatrics. 1975;56(1):129-131.
4. Ney AC, English JC III, Greer KE. Coexistent infections on a child’s distal phalanx: blistering dactylitis and herpetic whitlow. Cutis. 2002;69(1):46-48.
5. Norcross MC Jr, Mitchell DF. Blistering distal dactylitis caused by Staphylococcus aureus. Cutis. 1993;51(5):353-354.
6. Oyedeji OA, Oluwadiya KS, Aremu AA. Blistering digital dactylitis complicated by osteomyelitis and amputation in an HIV-positive infant. J Int Assoc Physicians AIDS Care (Chic). 2011;10(5):280-282.