Atypical placental site nodules: A Clinicopathologic study of 11 cases at an urban academic institution

Objective To characterize cases of atypical placental site nodules (APSNs), including their clinical presentation, diagnosis, management, and outcomes at an urban academic institution. Methods Cases with a pathology diagnosis of APSN were reviewed from January 2019 to July 2024. Available slides were reviewed by pathologists and chart review was conducted for demographic and clinical information. Results Eleven cases of APSN were identified. Two cases were incidentally diagnosed after hysterectomy for other indications. Abnormal Papanicolaou testing (4/11, 36.4%) was the most common presenting symptom followed by menorrhagia (2/11, 18.2%). The median interval between antecedent pregnancy and diagnosis of APSN was 29.4 months (range: 2.7–288.0 months). All cases had increased trophoblastic cellularity (defined as >25% cellularity) and ≥ 5% Ki-67 proliferation index. Six cases had management and follow-up data available: 2 (25.0%) opted for hysterectomy and 4 (44.4%) chose conservative management. Additional pathology results included 1 APSN (16.7%), 1 placental site nodule (PSN) (16.7%), and 4 (66.7%) with no evidence of gestational trophoblastic disease. No case was associated with malignant gestational trophoblastic neoplasia (GTN) at time of diagnosis, final pathology, or subsequent follow-up when available. Discussion Most cases did not present with abnormal uterine bleeding or menorrhagia prior to diagnosis. Most were incidentally diagnosed following presentation for abnormal Papanicolaou testing. Due to the incidental nature of its diagnosis, APSN may be more prevalent than previously considered. We also observed no association of APSN with GTN. The clinical course of APSN may be overall more benign.