Visceral myopathy: the importance of electronic microscopy in the diagnosis of rare diseases

Abstract

Intestinal pseudo-obstruction syndrome in childhood is rare and its etiology is varied. Among the causes are degenerative alterations of the myenteric plexus (visceral neuropathies), the most representative being Hirschsprung's disease; intestinal neuronal dysplasia, which presents a normal number of neurons but with alterations in their development and, finally, visceral myopathies that represent the most common cause of primary intestinal pseudo-obstruction and in which the innervation is completely normal, presenting abnormalities smooth muscle that affect the entire wall of the digestive tract, and may be of interest to other organs, such as the urinary tract.

A 5-year-old male patient with episodes of abdominal distension, colic pain and vomiting of 3 years of evolution. With this picture of intestinal pseudo-obstruction, an abdominal tomography was performed that showed marked dilatation of the small intestine and colon. A rectal biopsy was performed, which at the light microscopy level showed alterations of the muscularis propria, characterized by degenerative changes in the inner layer of smooth muscle and cytoplasmic vacuolization, without evidence of inflammation or fibrosis. Ganglion cells of the myenteric and submucosal plexuses are visible, ruling out Hirschsprung's disease. A study of the seromuscular wall of the colon by transmission electron microscopy was requested. The ultrastructure showed the presence of cytoplasmic vacuoles, making the clinical and imaging findings compatible with Visceral Myopathy.

Visceral Myopathy, cause of intestinal pseudo-obstruction syndrome, is a condition characterized by the lack of development of the outer muscular layer of the entire digestive tract. In this pathology, transmission electron microscopy is a very important tool to arrive at its diagnosis, with cytoplasmic vacuolization being the most characteristic ultrastructural finding of this pathology. For this reason and due to the difficulty in establishing the diagnosis and, above all, the need to offer the patient an early and timely diagnosis, we decided to report this case.