Subscapularis pyomyositis, a rare cause of shoulder pain, in a patient without apparent risk factors: A case report

INTRODUCTION

Pyomyositis, previously tropical, now seen more in temperate zones, particularly in those with HIV, cancer, or diabetes. Even healthy individuals, like athletes, can get it post-exercise or minor injuries. Our patient, in a desert-like area, adds an interesting aspect. Diagnosing is challenging due to deep tissue occurrence and subtle symptoms, leading to delayed detection and higher risks of morbidity.

PRESENTATION OF CASE

A 45-year-old female patient presented with acute left shoulder pain and functional impairment, exacerbated by movement. Clinical examination revealed tenderness upon deep palpation in the left upper posterior thoracic region and restricted range of motion of the affected shoulder.

DISCUSSION

Initial assessments at medical facilities suggested musculoskeletal strain and lower cervical disc prolapse despite normal X-ray results. MRI scans confirmed a developing abscess in the left subscapularis muscle, with intraoperative findings revealing extensive purulent fluid and necrotic tissue. Four surgeries drained the abscess and treated fat necrosis, with tailored antibiotics administered. Subsequent arthroscopy showed fibrous tissue, swelling, and inflammation. At the 3-month check-up, she had fully recovered, experiencing no pain or complications, and had almost regained full range of motion.

CONCLUSION

Shoulder pyomyositis presents diagnostic challenges, causing delayed treatment. This case highlights the importance of considering pyomyositis in severe shoulder pain cases, even without typical risk factors or inconclusive X-rays. Timely recognition, surgical drainage, tailored antibiotics, and physical therapy are crucial. An interdisciplinary approach with orthopaedic surgery, infectious disease specialists, radiology, and physical therapy is vital for comprehensive management, improving outcomes, and reducing complications.

Pyomyositis in the United States 2002-2014

OBJECTIVES

Primary pyomyositis is a bacterial infection of skeletal muscle first recognized in tropical regions of the world but needing characterization in temperate climates.

METHODS

This population-based study used the Healthcare Utilization Project/Nationwide Inpatient Sample database to characterize the trends of pyomyositis admissions in the United States from 2002-2014 using ICD-9 diagnostic codes.

RESULTS

We found a concerning more than three-fold increase in the incident pyomyositis admissions over our study period. The median length of stay was over twice as long compared to other hospitalized patients. Patients with pyomyositis were younger and more likely to be male and Black. There were more cases in the West and South compared to Midwest and Northeast. Age-adjusted odds ratios revealed significant association of pyomyositis with HIV, types 1 and 2 diabetes mellitus, hematologic malignancy, organ transplant, malnutrition, chronic kidney disease, obesity, and rheumatoid arthritis. The most commonly identified bacterial diagnosis was Staphylococcus aureus. Pseudomonas species were the most commonly identified gram-negative bacteria.

CONCLUSION

This nationwide review of pyomyositis in the United States suggests a concerning increase in incidence and provides information on the trends, demographics, risk factors, and causative organisms for pyomyositis in the United States.

Pyomyositis in Children

Primary pyomyositis in children is prevalent in the tropics and increasingly being recognised from temperate regions. Staphylococcus aureus remains the principle causative organism worldwide, while proportion of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is on rise. Commonly involved groups are around the pelvis and lower limbs. Clinical presentation depends on the stage of disease, most commonly a child presenting with limping with fever. Early diagnosis and management are crucial. The investigation of choice is MRI scan. Appropriate antibiotic treatment should be instituted at the earliest opportunity along with drainage. Majority of patients show excellent and complete recovery with no long-term complications once treatment is started early. A high level of awareness and suspicion of this condition is warranted from all paediatric clinicians.

Tuberculous pyomyositis: a re-emerging entity of many faces

Tuberculosis (TB) has become a global concern due to its increasing incidence, particularly in immunocompromised patients, closely following the migratory patterns of populations. TB pyomyositis is a rare extrapulmonary manifestation of TB. Its clinical presentation varies and requires a high degree of suspicion for early diagnosis. We present three patients diagnosed with TB pyomyositis: a 46-year-old man with dermatomyositis (DM) and hepatitis B who presented with fever, muscle weakness, and an abscess at the right proximal arm; a 71-year-old immunocompetent male, with a past medical history of tuberculous lymphadenopathy in childhood, who presented with a 2-month history of fever and pain at the right thigh, and a 44-year-old woman with systemic lupus erythematosus (SLE) on prednisone and methotrexate who presented with skin eruption at her thighs mimicking lupus panniculitis. In all three patients, Mycobacterium tuberculosis was identified as the causative agent. The lack of specific signs, the false negative tuberculin skin test in some cases, and the unfamiliarity of many clinicians with this entity can cause diagnostic delays. Prompt diagnosis requires a high index of suspicion especially in immunocompromised patients with fever.