Granulomatous myopathy: its relationship to sarcoidosis and polymyositis.

In three cases of generalized muscle weakness, muscle biopsy revealed well-defined, non-caseating epithelioid granulomata with giant cells. In one of these patients there was, in addition, a high serum CPK and histological evidence of widespread muscle cell degeneration and regeneration, apparently unrelated to the granulomatous process. In a re-examination of the histopathology of these cases, using biopsy material from a fourth case of proven sarcoidosis as a standard, it was concluded that there are no special features of the granulomatous/giant cell process which permit the separation of the case of presumed polymyositis. However, it appeared that granulomata per se do not exert a significant ill effect on surrounding muscle cells, and that evidence of widespread degeneration of muscle cells is the important point of distinction.