Gluteal fibrosis.

The authors report a histological study of gluteal fibrosis, a disease which in the last few years has become a clinical entity in its own right. This condition is of more frequent occurance than the earlier reports seem to indicate. The salient point emerging from this investigationis that teno-fascial changes exist as well as changes in the striated muscle. These teno-fascial changes are clearly more striking and extensive and should be regarded as primary. They consist of fibrotic thickening of the whole teno-fascial component with regressive changes leading to pseudocystic cavities and eventually to substitution by fibroadipose or adipose connective tissue. The muscle changes, however, generally appear to be localised near the tendon and present the features of simple atrophy and patchy necrosis, also eventually leading to zones of fibrous or fibroadipose substitution. These findings, though not offering a complete explantation of the pathogenesis, justify the description of the syndrome as a primary teno-fascial fibrosis with secondary muscle changes.