Histologic Reaction Patterns of Lymph Node Involvement in Ovarian Serous Borderline Tumors.

Context.—: Lymph node (LN) involvement (LNI) is not infrequently observed in ovarian serous borderline tumors (SBTs) but is not considered equivalent to malignant tumor metastasis, as it reportedly does not impact recurrence or survival in patients with SBT. However, the reasons underlying the insignificant clinical impact of LNI remain unclear.

Objective.—: To determine whether histologic reaction patterns (HRPs) are associated with SBT prognosis.

Design.—: We compared HRPs around tumor cell clusters in LNs of patients with SBT and low-grade serous carcinoma. HRPs were classified into 4 categories (HRP 1-HRP 4) based on tumor cell location in LNs, the presence of their adhesion to surrounding lymphoid tissue, or pericellular desmoplastic reactions.

Results.—: Although LNI itself was linked to reduced recurrence-free survival (RFS), no recurrence was observed in patients with HRP 1 or 2, characterized by freely floating tumor cells in the lumens of afferent/efferent lymphatics or intranodal sinus with surrounding free spaces. Conversely, HRP 3 or higher, characterized by firm tumor cell adhesion to lymphoid tissue (HRP 3) or peritumoral desmoplastic reaction (HRP 4), independently impacted RFS, albeit not overall survival.

Conclusions.—: The prognosis of SBT with LNI is not uniformly favorable, and HRPs around the LNI significantly influence patient outcomes. Patients with firm tumor cell adhesion to surrounding tissue, with or without peritumoral desmoplastic reaction (HRP ≥3), independently experience decreased RFS, although this does not correlate with reduced overall survival.