Microtubuloreticular Structures in Autoimmune-related Myopathy

Abstract

Microtubuloreticular structures are composed of undulating reticulated microtubules lying within dilated cisternae of rough endoplasmic reticulum, measuring 18-27 nm in diameter. Although these structures occasionally occur in normal mammalian cells, most examples come from the tissues of diseased individuals, particularly from cases of autoimmune disease and viral infection. We have experienced 10 cases of inflammatory myopathy in the last 2 years. Of particular interest was their presence in the pericytes (3 cases), stromal fibroblasts (2 cases) and histiocytes (1 case) as well as in the endothelial cells in 8 cases. Two cases of polymyositis revealed a marked degenerative change without evident microtubuloreticular structures in the capillary endothelial cells. These findings confirm the previous reports that these structures are of considerable diagnostic value for autoimmune-related myopathy when taken in conjunction with other clinicopathological features, and also prove that the pericyte should be included as the target cell of microtubuloreticular structures.