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Other names: Tropical pyomyositis or Myositis tropicans
Transverse T2 magnetic resonance imaging section through the hip region showing abscess collection in a patient with pyomyositis.
Diagnostic methodDiagnostic method used for PM includes ultrasound, CT scan and MRI. Ultrasound can be helpful in showing muscular heterogeneity or a purulent collection but it is not useful during the first stage of the disease. CT scan can confirm the diagnosis before abscesses occur with enlargement of the involved muscles and hypodensity when abscess is present, terogenous attenuation and fluid collection with rim enhancement can be found. MRI is useful to assess PM and determine its localization and extension

Pyomyositis is a bacterial infection of the skeletal muscles which results in an abscess. Pyomyositis is most common in tropical areas but can also occur in temperate zones.

Signs and symptoms

Forearm of individual with tropical pyomyositis in extensor musculature

The clinical presentation of pyomyositis is as follows:[1]

  • Pain in affected muscle
  • Fever
  • Abscess formation

Risk factors

In terms of factors that may place an individual at risk of developing pyomyositis we find:[1]


Diagnosis is done via the following manner:[citation needed]

  • Pus discharge culture and sensitivity
  • X ray of the part to rule out osteomyelitis
  • Creatinine phosphokinase (more than 50,000 units)
  • MRI is useful
  • Ultrasound guided aspiration


The abscesses within the muscle must be drained surgically (not all patient require surgery if there is no abscess). Antibiotics are given for a minimum of three weeks to clear the infection.[2]


Pyomyositis is most often caused by the bacterium Staphylococcus aureus.[3] The infection can affect any skeletal muscle, but most often infects the large muscle groups such as the quadriceps or gluteal muscles.[2][4][5]

Pyomyositis is mainly a disease of children and was first described by Scriba in 1885. Most patients are aged 2 to 5 years, but infection may occur in any age group.[6][7] Infection often follows minor trauma and is more common in the tropics, where it accounts for 4% of all hospital admissions. In temperate countries such as the US, pyomyositis was a rare condition (accounting for 1 in 3000 pediatric admissions), but has become more common since the appearance of the USA300 strain of MRSA.[2][4][5]

Gonococcal pyomyositis is a rare infection caused by Neisseria gonorrhoeae.[8]


  1. 1.0 1.1 "Pyomyositis - National Organization for Rare Disorders". 16 June 2022. Archived from the original on 5 February 2023. Retrieved 5 February 2023.
  2. 2.0 2.1 2.2 Pannaraj PS, Hulten KG, Gonzalez BE, Mason EO Jr, Kaplan SL (2006). "Clin Infect Dis". Clinical Infectious Diseases. 43 (8): 953–60. doi:10.1086/507637. PMID 16983604.
  3. Chauhan S, Jain S, Varma S, Chauhan SS (2004). "Tropical pyomyositis (myositis tropicans): current perspective". Postgrad Med J. 80 (943): 267–70. doi:10.1136/pgmj.2003.009274. PMC 1743005. PMID 15138315. Archived from the original on 2019-12-11. Retrieved 2022-08-14.
  4. 4.0 4.1 Ovadia D, Ezra E, Ben-Sira L, et al. (2007). "Primary pyomyositis in children: a retrospective analysis of 11 cases". J Pediatr Orthop B. 16 (2): 153–159. doi:10.1097/BPB.0b013e3280140548. PMID 17273045.
  5. 5.0 5.1 Mitsionis GI, Manoudis GN, Lykissas MG, et al. (2009). "Pyomyositis in children: early diagnosis and treatment". J Pediatr Surg. 44 (11): 2173–178. doi:10.1016/j.jpedsurg.2009.02.053. PMID 19944229.
  6. Small LN, Ross JJ (2005). "Tropical and temperate pyomyositis". Infect Dis Clin North Am. 19 (4): 981–989. doi:10.1016/j.idc.2005.08.003. PMID 16297743.
  7. Taksande A, Vilhekar K, Gupta S (2009). "Primary pyomyositis in a child". Int J Infect Dis. 13 (4): e149–e151. doi:10.1016/j.ijid.2008.08.013. PMID 19013093.
  8. Jensen M (2021). "Neisseria gonorrhoeae pyomyositis complicated by compartment syndrome: A rare manifestation of disseminated gonococcal infection". IDCases. 23: e00985. doi:10.1016/j.idcr.2020.e00985. PMC 7695882. PMID 33294370.
  • Maravelas R, Melgar TA, Vos D, Lima N, Sadarangani S (2020). "Pyomyositis in the United States 2002-2014". J Infect. 80(5):497-503. doi:10.1016/j.jinf.2020.02.005. PMID 32147332.

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