SBT microinvasion thread
Pathologist Janira Navarro posted high‑detail images distinguishing serous borderline tumor microinvasion from microinvasive low‑grade serous carcinoma, highlighting invasion under 5 mm and surveillance implications. Her thread stressed that microinvasive cells often mirror the non‑invasive component cytologically, a nuance that affects reporting and follow‑up decisions. (x.com) (x.com)
WHO 2020 and the ICCR core dataset endorse the single preferred term "serous borderline tumor" and separate microinvasion within SBT from bona fide low‑grade serous carcinoma for reporting purposes. (pathologyoutlines.com) Recent expert consensus and position papers specify a pragmatic greatest‑dimension cutoff of 5 mm when discussing microinvasive disease and recommend treating a label of “microinvasive low‑grade serous carcinoma” as provisional until further sampling excludes overt invasion. (international-journal-of-gynecological-cancer.com) Large case series place microinvasion within the SBT spectrum at roughly 10% of cases, and multiple pathology series describe the microinvasive foci as cytologically congruent with the surface borderline component (conventional/eosinophilic cell pattern). (webpathology.com) Outcome data indicate that microinvasion alone is not consistently an independent adverse prognostic factor in most studies, whereas truly invasive peritoneal implants carry substantially higher mortality (reported series show invasive‑implant mortality ~34% versus ~4.7% for non‑invasive implants). (mdpi.com) Molecular profiling shows low‑grade serous carcinomas and many SBTs cluster in the MAPK pathway, with KRAS or BRAF alterations in ~50–60% of LGSCs, and BRAFV600E‑positive borderline tumors associated in some cohorts with lower subsequent carcinoma risk. (pathologyoutlines.com) Practical reporting recommendations in the surgical pathology record include explicit measurement of the largest stromal invasive focus in millimeters, descriptive cytologic comment (e.g., conventional/eosinophilic vs overtly infiltrative), and documentation of any additional block sampling performed when invasion approaches the 5 mm threshold. (iccr-cancer.org) Therapeutic and surveillance practice reflects stage at diagnosis—about 75% of borderline tumors present as FIGO stage I—and current guidance generally reserves adjuvant systemic therapy for invasive carcinoma while advising either closer clinical surveillance or completion staging when microinvasion or micropapillary architecture raises concern. (cancer.gov)
