A review traces how mixed epithelial-neuroendocrine tumours are classified under the 2026 WHO scheme, and the distinctions matter at sign-out. Mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) stays defined as two morphologically recognisable components, each at least 30% of the tumour, with clear neuroendocrine marker expression in the neuroendocrine part.
The clarification is what does not qualify. A tumour whose non-neuroendocrine component is only a precursor or intramucosal lesion is not a MiNEN; the correct wording is, for example, 'neuroendocrine carcinoma arising from an adenoma'. The WHO 6th edition also introduces amphicrine-like carcinoma for tumours where the two lines of differentiation are intimately intermixed, in the same or similar cells, rather than forming the distinct zones seen in MiNEN.
Both MiNEN and amphicrine-like carcinoma are families of tumours rather than single diagnoses, and both need immunohistochemical confirmation. Molecular data support a clonal origin from a common precursor rather than a collision of two tumours, which is the concept to carry into reporting.
- MiNEN requires two recognisable components, each at least 30%, with clear neuroendocrine marker expression.
- A non-neuroendocrine component that is only a precursor or intramucosal lesion does not make a MiNEN.
- Prefer wording such as 'neuroendocrine carcinoma arising from an adenoma' in that situation.
- Amphicrine-like carcinoma denotes intimately intermixed differentiation, not distinct zones.
- Confirm both with immunohistochemistry; the biology is clonal, not a collision tumour.
Why it matters
The terminology a report uses drives downstream management, so a loose 'MiNEN' label on a precursor-only tumour misclassifies it.
Don't overread it
This is a classification review, not outcome data; it standardises terminology rather than changing prognosis or treatment thresholds.
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