Rigid spine syndrome: histological examinations of male and female cases.

Histological findings in the limb-muscle of two new cases of Rigid Spine Syndrome are described. The first male case exhibited a disproportion in fiber type with predominance of the type II fibers with a slight increase of large fibers. Some of the type I fibers were slightly atrophic. No other consistent abnormalities could be seen, excepted thickness of vessel basal lamina. The second female case had a relatively distinct muscular pattern. Necrotizing phenomenon were mild without fibrosis. Type I predominance were obvious. Atrophic and hypertrophic fibers could be seen in both types populations, with a relatively higher rate in type II. These two additional cases and those of the literature showed varied non specific histology, without any histo-chemical nor ultrastructural characteristic pattern.