NME Distribution — Focal
Focal NME describes enhancement that is localized and occupies less than one quadrant but does not follow a segmental or linear distribution.
Definition
Enhancement that:
- Is localized to a small area
- Occupies less than one quadrant
- Does NOT follow a segmental or linear distribution
Focal is the catch-all NME distribution descriptor used when the enhancement pattern does not fit diffuse, regional, linear, or segmental criteria.
Imaging Appearance
- Small, localized area of enhancement
- Does not have the cone/triangular shape of segmental NME
- Does not follow a linear/ductal pattern
- Less than one quadrant in extent
Suspicion Level
Focal NME is the least suspicious distribution, but can still represent significant pathology:
- Overlap with BPE is greatest for focal NME — careful comparison to contralateral breast and prior exams is important
- Small focal NME may represent BPE, fibrocystic change, or DCIS
Differential Diagnosis
| Diagnosis | Supporting Features |
|---|---|
| DCIS | Focal, clumped NME — most important to exclude |
| IDC | Focal, clumped NME |
| Fibrocystic change | Focal, clumped NME — benign |
| PASH | Focal, heterogeneous NME — benign |
| BPE | Symmetric or known bilateral pattern; not a unique finding |
Examples from Source
- Focal, heterogeneous NME → PASH (benign)
- Focal, clumped NME → Fibrocystic change (benign)
- Focal, clumped NME → DCIS (malignant)
- Focal, clumped NME → IDC and DCIS (malignant)
Board Pearl
Focal NME that is clumped and distinct from BPE warrants biopsy consideration, as DCIS can present as focal clumped NME. Compare carefully with prior exams and contralateral breast.