Intralobular Nephrogenic Rest
Also written as: ILNR
An abnormally persistent focus of embryonic metanephric tissue located within the renal lobule, considered a precursor lesion to Wilms tumour and distinct from the perilobar variant by its intralobar position.
Full Definition
Intralobular nephrogenic rests (ILNRs) are clusters of retained blastemal, stromal, or epithelial cells situated within the substance of the renal lobe rather than at its periphery. Their intralobar position distinguishes them from perilobar nephrogenic rests (PLNRs), a distinction that carries prognostic and syndromic significance: ILNRs are more commonly associated with Denys–Drash syndrome and diffuse aniridia. Both subtypes are recognised precursors of Wilms tumour and are collectively termed nephroblastomatosis when multifocal or diffuse. In pathology reports, the subtype must be specified because treatment and surveillance protocols differ. Editors should not conflate 'intralobular' with 'intralobar sequestration', an entirely unrelated pulmonary entity.
Usage
Usage note: Do not shorten to 'intralobar rest'; the correct adjective is 'intralobular'. Distinguish from 'perilobar nephrogenic rest' in all edited documents.
In Context
- "Microscopy revealed multifocal intralobular nephrogenic rests throughout the contralateral kidney, prompting enhanced surveillance." — Nephrectomy specimen report
- "The editor queried whether 'intralobar' in the draft referred to a pulmonary sequestration or to an intralobular nephrogenic rest." — Editorial query log