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Arch Dis Child. 2007 October; 92(10): 871.
PMCID: PMC2083235

Pyomyositis secondary to chickenpox

Necrotising fasciitis and osteomyelitis are uncommon but life threatening complications of chickenpox, particularly in otherwise healthy infants. These diseases are usually caused by group A β‐haemolytic streptococcus (GABHS) and Staphylococcus aureus.1 Presenting clinical features may be continuous or recurrent fevers, localised redness and swelling, refusal to weight bear or shock.

Pyomyositis, also a known complication of chickenpox, is an important differential diagnosis of necrotising fasciitis. It is important to differentiate between the two as urgent surgical exploration can be life saving in the case of necrotising fasciitis, whereas more conservative methods can be used in pyomyositis.2

MRI may be useful in localising the site of infection and differentiating cellulitis from necrotising fasciitis, septic arthritis, pyomyositis and osteomyelitis. It also provides information about the depth and extent of infection and is useful in planning debridement.3

A 6‐month‐old baby presented with swelling in the right anterior chest and both knees of 4 h duration. She had developed chickenpox 12 days prior to presentation and on admission all skin lesion had healed. A provisional diagnosis of necrotising fasciitis was made following an urgent MRI which showed a lobulated collection adjacent to but not invading the shoulder joint (fig 1). A large collection was also noted along the left femur extending down to the tibia with underlying muscular inflammation, consistent with necrotising fasciitis. Expedient debridement undertaken by the orthopaedic surgeons revealed pus but no necrotic muscle or bony tissue. A diagnosis of pyomyositis was made at this stage.

figure ac124545.f1
Figure 1 MRI of the 6‐month‐old baby.


Competing interests: None.

Parental/guardian informed consent was obtained for publication of the person's details in this report.


1. Aebi C, Shmed A, Ramilo O. Bacterial complications of primary varicella infection in children. Clin Infect Dis 1996. 23698–705.705 [PubMed]
2. Clark P, Davidson D, Letts M. et al Necrotising fasciitis secondary to chicken pox infection in children. Can J Surg 2003. 469–14.14 [PubMed]
3. Tang W M, Wong J W K, Wong L L S. et al Streptococcal necrotizing myositis: the role of magnetic resonance imaging. J Bone Joint Surg Am 2001. 831723–1726.1726 [PubMed]

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