Unfavourable Histology
A histological designation in paediatric renal tumour classification indicating the presence of anaplasia (diffuse or focal), associated with a significantly worse prognosis and intensified treatment protocols.
Full Definition
In the Children's Oncology Group (COG) classification of Wilms tumour, unfavourable histology refers specifically to the presence of anaplasia—defined by markedly enlarged, hyperchromatic nuclei and abnormal mitotic figures—within the tumour. Anaplasia is classified as focal or diffuse, with diffuse anaplasia conferring the most adverse prognosis. The designation directly determines chemotherapy regimen and radiation decisions. Editors must ensure that 'unfavourable histology' is used as a formal, capitalised classification term in reports following COG guidelines, and should not paraphrase it as 'poor histology' or 'bad histology'.
Usage
Usage note: Treat as a formal classification term in COG-aligned documents; capitalise both words when used as a designation.
In Context
- "The tumour was reclassified as unfavourable histology following central pathology review confirming diffuse anaplasia." — Tumour board report
- "Editors should retain 'Unfavourable Histology' as a proper classification term, not paraphrase it as 'poor-prognosis histology'." — Style guide annotation