Three-generation familial visceral myopathy with alpha-actin-positive inclusion bodies in intestinal smooth muscle.

We report the clinical and histopathologic findings of a family with 7 affected members in 3 generations suffering from autosomal dominant visceral myopathy. All patients presented with chronic intestinal pseudo-obstruction affecting especially the entire small bowel. Histologic abnormalities involved intestinal smooth muscle, with degeneration and fibrosis of the muscularis propria. In addition, the inner circular layer of the muscularis propria contained alpha-smooth muscle actin-positive and, in more advanced disease, also periodic acid-Schiff-positive inclusion bodies. The inclusions were invisible in routine hematoxylin-eosin-stained sections, but were visible in immunohistochemical stainings for alpha-smooth muscle actin. No abnormality was evident in muscularis mucosae or in blood vessels, and the findings remained unidentified in mucosal biopsy specimens. To our knowledge, this is the first reported alpha-actin-positive inclusion body finding in familial visceral myopathy.