Eosinophilic/T-cell Chorionic Vasculitis: Its Incidence Is Increasing but It Does Not Appear to Recur in Subsequent Pregnancies.

INTRODUCTION: Eosinophilic/T-cell chorionic vasculitis (E/TCV), an incidental finding primarily in third trimester placentas, is characterized by eosinophils and CD3+ T lymphocytes infiltrating at least 1 chorionic and/or stem villous vessels. Its etiology and clinical significance are unclear.

METHODS: Placental pathology reports issued by 8 pediatric-perinatal pathologists at Alberta Children's Hospital were retrieved from the lab information system (2010-2022), and candidate reports were identified using a Perl script searching for "eosinophil." Candidate diagnoses of E/TCV were validated by pathologist review.

RESULTS: 38,058 placenta reports from 34,643 patients were reviewed; 328 cases of E/TCV were identified, for an overall incidence of 0.86%. Incidence increased 23% per year, from 0.11% in 2010 to 1.5% in 2021 ( P  < .01). This temporal change was observed for all pathologists; the incidence of identified multifocality also increased over time ( P  < .01). Umbilical vascular involvement was exceedingly rare. No variation in incidence was attributable to season. We received more than 1 placenta from 46 mothers with an E/TCV placental diagnosis; examination of >1 placenta did not reveal any mother with >1 E/TCV diagnosis.

CONCLUSIONS: The incidence of E/TCV increased steadily over a ~12-year period and no recurrent cases were observed.