Cutaneous Nerve Lesions in Prurigo Nodularis

Skin biopsies from two patients with pruirgo nodularis were studied with the electron microscope. Lesions were found in the cutaneous myelinated and unmyelinated nerves. Schwann-cell cytoplasm showed large, irregular, membrane-bound, electron-lucent vacuoles. Umyelinated axons were distended and devoid of neurotubules and neurofilaments. Myelinated nerves showed various degrees of demyelination. Onion-bulb formations with a centrally located myelinated fibre were also observed and numerous mast cells were found in the cellular infiltrate. All these findings indicate the presence of a chronic peripheral neuropathy, the etiology of which remains to be determined.