Immunohistological analysis of sarcoid myopathy.

In six cases of granulomatous myopathy immunohistological analysis showed a typical pattern with macrophages and T4 cells diffusely distributed throughout the cellular exudate. T8 lymphocytes were interspersed irregularly within the granulomatous cellular infiltrate early in granuloma maturation and in later stages predominantly confined to a lymphocytic mantle surrounding the granulomas. The cellular infiltrate displayed numerous activated HLA-DR and interleukin-2 receptor positive cells including cell proliferation. Increased connective tissue showed strong immunoreactivity for fibronectin and hyaluronate. Muscle fibres were negative for MHC class I molecules. Atrophic muscle fibres expressed desmin, a marker to distinguish desmin positive myogenic giant cells from desmin negative Langhans giant cells.