Unusual Case of Localized Upper Limbs and Truncal Edema Associated with Fever, Anemia, and Acute Kidney Injury

Figure 2

There are clustered fibers with cytoplasmic staining (arrow). Cytoplasmic activation of the membrane attack complex (MAC) is seen in necrotic myofibers due to ongoing necrosis. The background also shows small brown dots between muscle cells (arrowhead). These correspond to capillaries with abnormal expression of the MAC due to capillary damage in dermatomyositis. MAC immunohistochemistry stain.