[Muscular polyarteritis nodosa-a case-based review]

Myalgia is a common but unspecific set of symptoms that may be caused by orthopedic, neurological and internal medical conditions, often resulting in a diagnostic challenge. Muscular polyarteritis nodosa (PAN) is a rare differential diagnosis of myalgia with elevated serological inflammatory markers.

Based on three clinical cases and the literature this review describes the essential clinical and diagnostic features of muscular PAN.

Muscular PAN typically presents with immobilizing myalgia confined to the lower limbs and elevated serological inflammatory markers but often normal creatine kinase (CK) levels. Contrast-enhanced magnetic resonance imaging of the affected muscles, which can often mimic myositis, and muscle biopsy provide the relevant histological findings that lead to the diagnosis of a vasculitis.

With respect to own experiences and the reviewed literature, muscular PAN should be considered as a possible diagnosis in cases of myalgia with elevated inflammatory markers but normal CK levels and a lack of further symptoms typical for vasculitis.