Eosinophilic fasciitis: an ultrastructural and immunohistochemical study of the intermediate filament protein skeletin in regenerating muscle fibres.

In a case of eosinophilic fasciitis with pronounced muscle involvement non-specific ultrastructural signs of degeneration were observed in areas of perifascicular atrophy. By combined immunohistochemical and electron microscopical techniques intermediate skeletin filaments were demonstrated. These filaments, when found in combination with nuclei with large nucleoli and an abundance of polyribosomes are a sign of regeneration of muscle fibres. This finding is a useful indicator in assessing the prognosis and therapy of muscle involvement in eosinophilic fasciitis.