[Orbital myositis: an ultrastructural and immunohistochemical study]. / Miositis orbitaria: Estudio ultraestructural e inmunohistoquímico.

We present a morphological and ultrastructural study from one case of orbitary myositis in a 35 years old male patient with asymmetrical localytation and clinical behaviour as a tumor. The morphological study shows a chronic inflammatory lesion which causes atrophy and necrosis of the muscular tissue. On the ultrastructural image it is remarkable the atrophy of the muscle fibers with loos of the sarcomers, joined with signs of regeneration. The inflammatory infiltrate is polimorfous, with T and B cells immunihistochemically detected. There is also a macrophagic population identified by the morphology and immunohistochemistry with positivity for alfa-1-chymiotrypsin and alfa-1-anti trypsin. An important fibroblastic activity is show. On the discussion a possible pathogenesis for this entity is considered.