Recurrent Benign Acute Childhood Myositis (BACM) and Incidental Generalised Joint Hypermobility (GJH); A Case Study and Discussion

Abstract

Benign Acute Childhood Myositis (BACM) is rare clinical entity with an incidence of 2.69 cases per 100,000 that is caused by a range of viral, bacterial and rarely fungal pathogens. Recurrent BACM is even more rare with unknown incidence. Despite BACM being an unusual condition, it is widely reported in the literature, however a lack of knowledge results in missed, or delayed diagnosis. This case report discusses a rare presentation of recurrent BACM in an 11 year old female who presented to the authors’ rural emergency department with her mother. She had an 3 day history of difficulty walking following an upper respiratory tract infection that began 5 days prior to onset of symptoms. Examination revealed bilateral tender calves, sacroiliac joints and reluctance to weightbear with an abnormal gait. An incidental finding of generalised joint hypermobility (GJH) was noted. CK level was 2324 U/L. The patient’s mother disclosed a complex rheumatologic history on her side of the family and 2 identical episodes of BACM occurring within a 12 month timeframe. A discussion on current understanding of the pathophysiology of BACM and gaps in current literature is provided. BACM carries a small risk of rhabdomyolysis and renal failure and patients should be referred for assessment in the Emergency Department. No literature has explored the relationship between GJH and BACM and the relationship between recurrent BACM and other rheumatic diseases such as autoimmune juvenile myositis, or systemic myopathies is not known.