Atypical placental site nodules: Clinicopathologic features, management and patient outcomes in an institutional series

Objective: To report the New England Trophoblastic Disease Center (NETDC) experience with atypical placental site nodules (APSN).

Methods: The NETDC registry was reviewed from 2005 to 2022 and clinical data abstracted. Expert pathologists in GTD reviewed available slides with concurrent immunohistochemical analysis. Targeted deep sequencing was performed for four cases.

Results: Among 35 cases of APSN identified, 29 had clinical and demographic data available. Abnormal uterine bleeding (59.3%) was the most common presenting symptom. Most women (79.3%) had an antecedent live birth. Two cases were incidentally diagnosed after hysterectomy for other indications, and one case lost to follow-up. Among the remaining 26 cases, 11 (42.3%) opted for hysterectomy and 15 for re-sampling (57.7%), among whom 3 later underwent hysterectomy for persistent APSN. Subsequent obstetrical outcomes included 3 spontaneous abortions, 1 therapeutic abortion, 1 ectopic pregnancy, 2 cesarean sections, 1 cesarean hysterectomy, and 1 spontaneous vaginal delivery. Subsequent pathology was available for 26 cases: 4 epithelioid trophoblastic tumors (15.4%), 9 APSN (34.6%), 3 PSN (11.5%), and 10 without abnormalities (38.4%). Histopathologic characteristics of APSN included moderate to severe cytologic atypia, median Ki-67 proliferation index of 8%, and typical immunohistochemical profiles (diffuse or multifocal positivity for p63 and GATA-3 and absent or focal CD146). No histopathologic feature predicted ETT. Among 4 sequenced cases, no recurrent genomic features were identified.

Conclusions: APSN is a rare form of gestational trophoblastic proliferation with uncertain malignant potential. While normal obstetric outcomes are possible, the persistence rate is high, and definitive management remains hysterectomy.