- Design
- Cross-sectional immunohistochemistry study
- Population
- 408 tubal epithelial samples from 262 patients, plus 30 high-grade serous carcinomas
- Primary outcome
- Proportion with high FRα expression (PS2+ scoring)
- Effect
- High expression in 73.2% of STIC and 76.7% of HGSC; uncommon in STIL and earlier lesions
This American Journal of Surgical Pathology study, published on 1 September, stained 408 fallopian tube epithelial samples from 262 patients for folate receptor alpha (FRα): normal tube, secretory cell expansions and outgrowths, serous tubal intraepithelial lesions (STIL) and serous tubal intraepithelial carcinomas (STIC), with 30 high-grade serous carcinomas for comparison.
High FRα expression was found in 73.2% of STICs and 76.7% of high-grade serous carcinomas, with no significant difference between them. Normal tube usually stayed below the high-expression threshold, and STIL and earlier lesions mostly showed low or no expression. BRCA-mutated STICs and carcinomas expressed more FRα than non-mutated ones.
The STIL-versus-STIC call is one of the least reproducible in gynaecological pathology and it carries weight, especially in risk-reducing salpingo-oophorectomy specimens. FRα is not a replacement for morphology, p53 and Ki-67, but it may add confidence in borderline cases. About a quarter of STICs did not show high expression, so a negative result does not exclude STIC.
- Consider FRα as an adjunct when morphology, p53 and Ki-67 leave a STIL-versus-STIC call uncertain.
- Diffuse high FRα favours STIC; low expression is the usual pattern in STIL.
- Do not use a negative FRα to exclude STIC; about a quarter of STICs were not high.
- Expect higher expression in BRCA-associated lesions.
- Seek a second opinion on borderline tubal lesions in risk-reducing specimens.
Why it matters
One of gynaecological pathology's least reproducible calls may gain a third supporting stain.
Don't overread it
This is a single cross-sectional series; the adjunct has not been validated for diagnostic accuracy against expert consensus.
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