Arias-Stella reaction with prominent nuclear pseudoinclusions simulating herpetic endometritis.

We studied a pronounced Arias-Stella reaction in an incomplete abortion curettage specimen; the gestational age was 8 weeks by size. The majority of cells in this reaction showed ground glass, eosinophilic nuclear "inclusions" simulating herpetic Cowdry type B nuclear inclusions. This was coupled with a history of herpetic stomatitis of the patient and her husband 2 weeks prior to the curettage, raising the question of viremia and transplacental herpetic endometrial infection. Immunoperoxidase staining using the PAP technique directed against Herpes simplex virus types 1 and 2 was negative. Ultrastructural analysis elucidated the true nature of the nuclear "inclusions" as pseudonuclear inclusions consisting of invaginations of cytoplasm within the nuclei. Viral particles were not found. We are unaware of any similar report, and present this case to suggest the possible differential diagnosis between herpetic endometritis with associated cytologic atypia and the Arias-Stella reaction.