Congenital Mesoblastic Nephroma
Pronunciation: mez-oh-BLAS-tik neh-FROH-mah
Also written as: CMN — Congenital Mesoblastic Nephroma
The most common renal tumour of the first three months of life, composed of spindle cells of fibroblastic or myofibroblastic type, and subdivided into classic, cellular, and mixed variants.
Full Definition
Congenital mesoblastic nephroma (CMN) is a fibroblastic or myofibroblastic renal neoplasm that is the most frequent renal mass diagnosed in the neonatal period and early infancy. The classic variant resembles infantile fibromatosis and carries an excellent prognosis after nephrectomy. The cellular variant, which harbours the ETV6–NTRK3 fusion identical to that of infantile fibrosarcoma, has a small risk of local recurrence or metastasis and requires complete excision margins. The mixed variant shares features of both. Editors must not confuse CMN with Wilms tumour, which is rare before six months of age, and should ensure that variant subtype is documented in the pathology report.
Usage
Usage note: Variant subtype is clinically significant and must be stated in the diagnostic line of the report.
In Context
- "The neonatal renal mass was resected and diagnosed as cellular congenital mesoblastic nephroma with positive ETV6–NTRK3 fusion on FISH." — Neonatal surgical pathology report
- "Authors should specify the CMN variant (classic, cellular, or mixed) as this determines follow-up intensity." — Manuscript editorial note