Testicular sex cord-stromal tumours are rare, and the 2022 WHO classification names many of them by analogy with ovarian tumours on morphology alone. Newer clinicopathological and molecular data show important differences from their ovarian counterparts.
An expert group drawn from the Genitourinary Pathology Society and the International Society of Urological Pathology has proposed a structured, four-tier classification: the group (sex cord, stroma or both), the category (phenotype, referenced to normal testis and ovary), the entity (tumours with shared clinicopathological or molecular features) and the histological pattern (recurrent morphological variants without distinct biology).
This was published in July 2026 and is a proposal, not yet WHO classification. For reporting pathologists, its main value now is separating entities that carry different behaviour from patterns that do not — which is where diagnostic over-reach often happens with rare tumours.
- Continue to report using the current WHO classification; the TESST scheme is a proposal.
- Separate true entities from histological patterns when describing a rare sex cord-stromal tumour.
- Do not assume behaviour from an ovarian analogue — testicular tumours may differ.
- Seek expert genitourinary review for rare or ambiguous testicular stromal tumours.
Why it matters
Naming testicular tumours after ovarian ones has imported assumptions about behaviour that may not hold.
Don't overread it
A consensus proposal, not an adopted classification or a validated prognostic system.
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