Ultrastructural Pathology of capillary endothelial cells in autoimmune inflammatory myopathies has been intensively investigated in the last two decades, but much less is known about the alterations of capillary pericytes. In other diseases as diabetes and arterial hypertension perycites abnormalities have been reported. In this work we report the pericyte ultrastructural pathology in autoimmune inflammatory myopathies.

Patients admitted to the study were attending the rheumatology clinics at the Caracas University Hospital. Diagnoses were systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, and muscle paraneoplastic phenomenon.

Needle muscle biopsies were processed with routine techniques for transmission electron microscopy and observed in a Hitachi H-500 electron microscope.

Two different processes were observed, pericyte hypertrophy and cell degeneration. In the first one cytoplasmic proliferation is evident (Fig. 1). Some capillaries embraced by the pericyte were found (Fig. 2). In the second one cytoplasmic vacuolation and capillary necrosis (Fig. 3) were evident. Usually, pericyte and endothelial degeneration were concomitant.