Haycocknema perplexum myositis: the first description of subclinical disease and a proposed distinctive triad to evoke clinical suspicion

INTRODUCTION: Haycocknema perplexum is an exceedingly rare cause of parasitic myositis endemic to Australia, more specifically, Tasmania and North Queensland. There is a paucity of literature regarding this diagnosis, with only nine previously described cases. DIAGNOSIS: This report details two cases of biopsy-confirmed H. perplexum myositis from Townsville University Hospital and describes the first-ever case of subclinical infection. There is limited known information regarding the H. perplexum life cycle and a definitive host which has hindered the development of a non-invasive diagnostic test. A review of the previously described cases has identified the hallmark features of this enigmatic condition: a triad of serological markers including deranged hepatic function, persistent eosinophilia and an elevated creatine kinase. CONCLUSIONS: This report aimed to raise awareness of H. perplexum myositis and the possibility of subclinical infection, which suggests a protracted disease course. Further research is required to identify a non-invasive diagnostic test, given that early diagnosis and timely initiation of albendazole treatment may drastically limit patient disability.