Tomaculous neuropathy classical findings

(A) Semithin cross-section shows a marked depletion of myelinated nerve fibers. Several myelinated fibers have a thick myelin sheath and an irregular contour, suggesting that they are tomacula. (B) Teased fibers reveal globular expansions of myelin measuring 30 µm to 50 µm in length located in both the paranodal and internodal regions. (C) Ultrathin sections demonstrate that the tomacula consists of closely apposed, redundant loops of myelin sheath wound around a myelinated fiber. Layers of uncompacted myelin lamellae are apparent. A redundant circle of myelin is present embedded in the myelin sheath. (Contributed by Dr. Florian Thomas.)