Skin biopsy is useful for the antemortem diagnosis of neuronal intranuclear inclusion disease

Background: Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in neuronal and somatic cells. Because of the variety of clinical manifestations, antemortem diagnosis of NIID is difficult. Methods: Seven skin biopsy samples from patients with familial NIID were evaluated histochemically, and the results were compared with those of skin samples from normal control subjects and from patients with other neurologic diseases. We also examined skin biopsy samples from patients with NIID by electron microscopy. Results: In NIID skin biopsy samples, intranuclear inclusions were observed in adipocytes, fibroblasts, and sweat gland cells. These inclusions were stained with both anti-ubiquitin and anti-SUMO1 antibodies. Electron microscopy revealed that the features of the intranuclear inclusions in adipocytes, fibroblasts, and sweat gland cells were identical to those of neuronal cells. Approximately 10% of adipocytes showed intranuclear inclusions. No intranuclear inclusions were identified in the skin samples from normal control subjects and patients with other neurologic diseases. Conclusions: Skin biopsy is an effective and less invasive antemortem diagnostic tool for NIID.