[Biotin-rich pseudoherpetic intranuclear inclusions. A diagnostic pitfall].

Biotin-rich pseudoherpetic nuclear inclusions may be observed in endometrial epithelial cells during pregnancy, post-partum or in association with choriocarcinoma. They may be observed in tumor cells in a few papillary carcinomas of the thyroid gland in young women. These inclusions may be responsible for false diagnoses of herpesvirus infection at morphological and immunocytochemical examination. They may be responsible for false positives in immunocytochemistry and in situ hybridization.