Chronic sarcoid myopathy mimicking facioscapulohumeral muscular dystrophy: a case report

Chronic sarcoid myopathy is a rare disorder characterized by intramuscular granulomas and generally presents with symmetrical proximal limb-girdle muscle weakness. Here, we present an atypical case of a 68-year-old male with a history of pulmonary sarcoidosis with strikingly asymmetric limb-girdle weakness, progressive >20 years, including periscapular, paraspinal, lower limb and subtle facial involvement, mimicking facioscapulohumeral muscular dystrophy. MR images revealed a striking asymmetric pattern of patchy muscle involvement of paraspinal, lower limb and right periscapular muscles without marked muscle oedema. Although a genetic myopathy was suspected, genetic testing for facioscapulohumeral muscular dystrophy (FSHD1/2) as well as whole exome sequencing remained negative. Muscle biopsy revealed myopathic features and widespread granulomatous inflammatory infiltrates without signs orienting towards a concomitant muscular dystrophy or inclusion body myositis. This case demonstrates that chronic sarcoid myopathy can present with a very slowly progressive, highly selective asymmetrical, multifocal pattern of muscle involvement.