Mucinous Borderline Tumor Associated with Mesonephric-like Proliferation: Further Evidence for a Possible New Origin of Ovarian Mucinous Neoplasms

Abstract

Some ovarian mucinous tumors are thought to originate from Brenner tumors and teratomas; however, data are limited on what could be the origin for the remaining tumors. We report a new case of ovarian mucinous borderline tumor/atypical proliferative mucinous tumor (MBT/APMT) co-existing with a mesonephric-like proliferation (MLP)/mesonephric-like hyperplasia (MLH). The patient was a 58-year-old woman who presented with a pelvic mass and abdominal pain. Pathology demonstrated an 11 cm MBT/APMT in the left ovary. In addition, the tumor contained one focal area (<1% of total tumor volume) of MLP/hyperplasia adjacent to, or intimately admixed with, mucinous epithelium, with an immunophenotype of diffuse Pax8 and Gata3 expression and negative TTF-1, ER, and PR staining. Pax8 was also weakly positive in the MBT/APMT component. Some mesonephric-like glands partially exhibited gastrointestinal-type mucinous metaplasia/differentiation. A polymerase chain reaction (PCR)-based Sanger sequencing demonstrated that a KRAS G12V mutation was present in both MLP/MLH and MBT/APMT components, providing further evidence to support their clonal relationship. We previously reported a series of similar cases and demonstrated a novel association between MLP, mesonephric-like adenocarcinoma and ovarian mucinous tumor. It is conceivable that benign MLPs may have ability to differentiate to lineage-specific mucinous lesions, and, as such, they may serve as a possible new origin of some ovarian mucinous neoplasms; in particular, Pax8-positive tumors. The current case provides additional evidence to support this theory.

Uterine Leiomyosarcoma Associated With Perivascular Epithelioid Cell Tumor

“…Similar to other biphasic tumors, 29–31 the question of what the etiologic relationship is between the LMS and PEComa also arises in this study. It is noteworthy that the title of the first study of uterine PEComas in 2002 also questioned what the relationship was between PEComas and smooth muscle tumors 32 .…”

“…Although cathepsin K is not a specific marker for PEComa and can be expressed in smooth muscle tumors, 8,26 in our experience, it usually shows focal/patchy staining in the latter rather than diffuse as in the former. GPNMB, a novel PEComa marker, exhibits a similar staining pattern to that of cathepsin K. 27,28 Similar to other biphasic tumors, [29][30][31] the question of what the etiologic relationship is between the LMS and PEComa also arises in this study. It is noteworthy that the title of the first study of uterine PEComas in 2002 also questioned what the relationship was between PEComas and smooth muscle tumors.…”