Figure 1. Early blistering stage.
Figure 2. Blisters have popped, leaving crusty lesions.
A 15-year-old adolescent presents to the clinic for evaluation and treatment of scattered blisters on both legs. The condition was first noted 5 days ago. The patient notes that the blisters were preceded by slight itching. He states that 3 of the blisters have “popped” and drained fluid. These sites continue to itch on occasion. The patient plays football but is unaware of any other players with similar lesions. The patient denies fever, fatigue, and swollen glands. Physical examination reveals 2 intact tense bullae (Figure 1) and 2 erythematous patches with scale (Figure 2).
Submit your diagnosis to see full explanation.
Impetigo is among the most common skin conditions in children aged 2 to 5 years but may occur at any age.1 The condition is caused by infection with Streptococcus pyogenes or Staphylococcus aureus, is highly contagious, and predominately affects the lower legs and face. Cuts and abrasions are common bacterial entrance points and contact sports such as football and rugby predispose athletes to transmission.2 Impetigo is most prevalent in tropical, resource-poor countries with more than 162 million children affected at any one time worldwide.3
Impetigo is classified as either bullous or nonbullous, with the latter representing 30% of all cases.1 Nonbullous impetigo begins as an erythematous macule that rapidly vesiculates and ruptures. The serous fluid dries leaving a honey-combed, crusted exudate. Rubbing and scratching can lead to rapid spread of lesions. Bullous impetigo presents with superficial, fragile bullae of varying size. Onset is rapid; spontaneous drainage of the lesions leaves a collarette of scale and crusts.
The diagnosis of impetigo is usually made clinically. Culture may be prudent to rule out methicillin-resistant S aureus (MRSA). Lesions should be lightly cleansed to remove superficial crusting. When not extensive, individual lesions may respond to treatment with topical mupirocin.4 A course of an oral antibiotic that covers both S aureus and S pyogenes is often instituted to decrease the duration and extent of disease.5
Brittany Spinosa-Weber, PA-C, is a physician assistant at the DermDox Dermatology Centers in Leola, Pennsylvania. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers in Pennsylvania, associate professor of medicine at Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
1. Hartman-Adams H, Banvard C, Juckett G. Impetigo: diagnosis and treatment. Am Fam Physician. 2014;90(4):229-235.
2. Ludlam H, Cookson B. Scrum kidney: epidemic pyoderma caused by a nephritogenic Streptococcus pyogenes in a rugby team. Lancet. 1986;2(8502):331-333. doi:10.1016/s0140-6736(86)90015-2
3. Bowen AC, Mahé A, Hay RJ, et al. The global epidemiology of impetigo: a systematic review of the population prevalence of impetigo and pyoderma. PLoS One. 2015;10(8):e0136789. doi:10.1371/journal.pone.0136789
4. Koning S, van der Sande R, Verhagen AP, et al. Interventions for impetigo. Cochrane Database Syst Rev. 2012;1(1):CD003261. doi:10.1002/14651858.CD003261.pub3
5. Nardi NM, Schaefer TJ. Impetigo. In: StatPearls. StatPearls Publishing; 2021 Jan. Updated 2021 Aug 11. Accessed September 17, 2021.
This article originally appeared on Clinical Advisor