Primary ovarian solid pseudopapillary neoplasm with CTNNB1 c.94G > T (p.D32Y) mutation: a case report

Primary solid pseudopapillary neoplasm originating in the ovary (SPN-O) is extremely rare, with only 15 reported cases in the English literature; of these, three harbor CTNNB1 mutations similar to pancreatic SPN. Here, we present a fourth SPN-O case with confirmed CTNNB1 mutation.

A 45-year-old woman presented with a 6 cm left ovarian mass. Gross examination revealed a predominantly cystic neoplasm. Microscopy demonstrated solid nests and pseudopapillary structures of uniform tumor cells with eosinophilic, foamy, or vacuolated cytoplasm. Mitotic activity and atypia were minimal. Ki-67 index was very low. Immunohistochemistry showed strong nuclear and cytoplasmic positivity for β-catenin and negativity for E-cadherin. Genetic analysis revealed a c.94G > T (p.D32Y) mutation in exon 3 of CTNNB1. Four years postoperatively, there was no recurrence or metastasis. These findings align with pancreatic SPN, supporting the theory of a shared Wnt/β-catenin oncogenic pathway.

The findings of this case reinforce the morphological, immunohistochemical, and molecular parallels between SPN-O and its pancreatic counterpart (SPN-P). The presence of a pathogenic CTNNB1 c.94G > T (p.D32Y) mutation-previously unreported in SPN-O-further supports the central role of Wnt/β-catenin dysregulation in tumorigenesis across anatomical sites. The absence of recurrence in this case aligns with most documented SPN-O outcomes, though metastatic potential underscores the need for long-term surveillance.

Primary ovarian SPN is an exceedingly rare tumor showing significant similarity to pancreatic SPN in morphology, immunophenotype, and molecular alterations.