AbstractFine granular (hyaline) intranuclear inclusion bodies were found in perivascular cells of a muscle and a sural nerve biopsy from a 32‐year‐old woman with slowly progressive motor disturbances. The hyaline nuclear inclusion bodies could be distinguished from other intranuclear hyaline inclusions by their granularity, the size of the granules (approximately 5–15 nm), and the positive iron staining reaction. They were not seen in muscle fibers or Schwann cells. Because of these apparently pathognomonic structural features the patient appears to present a condition that has not been described b