Delayed effort-induced swelling with myofasciitis and systemic manifestations: A so far unrecognized type of pressure-induced urticaria

Diseases characterized by recurrent symptoms with prolonged intervals without any clinical manifestations can pose diagnostic difficulties. Some diagnoses will be obvious but other situations can be very challenging.To nosologically delineate a new entity characterized by recurrent flares of induration of the forearms and legs with swelling of the extremities accompanied by intense fatigue and variable other symptoms.Retrospective observational study of patients recorded from 2000 to 2015. All patients included were seen during a consultation at the Dermatology Department of the University Hospital of Strasbourg, France. We retrieved the medical records from patients seen and recorded over the last 16 years having induration of the extremities, the forearm and the legs occurring between 4 and 12 hours after a physical effort accompanied by systemic signs that lasted for a few days. We analyzed in detail the clinical and biological features, evolution, and treatments of these patients.We included 6 males, with a mean age of 47 years; mean age at disease onset was 42. All patients were initially misdiagnosed as having rheumatic disorders. The mean delay before diagnosis was 5 years. The main complaint was painful induration or muscle soreness of the forearms and the legs associated with transient functional impairment and prolonged asthenia for a mean duration of 3.5 days. Induration of the deep soft tissues was very suggestive of myofasciitis. The delay between the triggering physical effort and the swelling was between 6 and 12 hours. Physical effort as triggering factor was never spontaneously mentioned. Two patients had partial response to high dose antihistamines and 2 other patients to the interleukin-1 inhibitor anakinra. One patient responded to hydroxychloroquine.The very stereotypical presentation in those 6 patients suggests that this is a recognizable entity characterized by effort-induced induration of forearms and/or legs, due to deep edematous myofascial involvement, occurring a few hours after a physical effort. We suggest to name this entity delayed effort-induced swelling with myofasciitis and systemic manifestations.