Chronic sarcoid myopathy mimicking sporadic inclusion body myositis

The patient was an 81-year-old woman. At age 73, she developed difficulties in climbing stairs and swallowing, and became unable to open bottles at age 74. She had been walking with a cane since age 76. Accidental chest X-ray findings showed bilateral hilar lymphadenopathy at age 78. Angiotensin converting enzyme (ACE) was elevated. Lymphocyte proliferation was prominent in bronchoalveolar lavage fluid. Sarcoidosis was suspected, but she was followed without treatment due to lack of respiratory symptoms. She became unable to walk without assistance at age 80 and visited our hospital with a complaint of gait disturbance at age 81. Moderate diffuse muscle atrophy in extremities was evident. Muscle weakness of finger flexion and knee extension were remarkable. The muscle involvement pattern was similar to sporadic inclusion body myositis (sIBM). However, radiographically, rectus femoris and semitendinosus muscles are selectively preserved. This radiogaphic finding was consistent with chronic sarcoid myopathy (CSM). We reached a final diagnosis of CSM based on the presence of granulomas in the muscle biopsy specimen, BHL in fluorodeoxyglucose positron-emission tomography, the previous finding of elevated ACE, and bronchoscopy results. In conclusion, CSM is a treatable disease and should thus be differentiated from sIBM. This should not be done solely based on clinical findings, but instead, muscle biopsy should be performed. Moreover, muscle selectivity may be useful in distinguishing between CSM and sIBM.