Mass T2 Signal — Hyperintense
T2 hyperintense mass signal indicates the mass is uniformly bright on T2-weighted imaging — as bright as a normal lymph node (“lymph node bright”).
Definition
The mass is uniformly bright throughout and “lymph node bright” — as bright as a normal-appearing axillary or intramammary lymph node on fat-suppressed T2-weighted imaging.
Internal Standard
Use a normal axillary or intramammary lymph node as the internal reference for T2 hyperintensity. The mass must be as bright as or brighter than the lymph node to qualify as T2 hyperintense.
When to Report T2 Signal
T2 signal should be assessed and reported when it influences assessment, specifically when combined with other benign-favoring features (oval, circumscribed, homogeneous/dark septations). It does NOT need to be reported when:
- The mass is definitively benign based on morphology alone
- The mass is clearly suspicious and T2 signal would not change management
The ≤ 2% Cancer Risk Combination
Board Pearl
A mass with ALL of the following features has a likelihood of malignancy ≤ 2%:
- Oval shape
- Circumscribed margin
- Homogeneous internal enhancement OR dark internal septations
- T2 hyperintense signal
Based on existing data and expert practice. ALL four features must be present.
Differential for T2 Hyperintense Enhancing Masses
| Diagnosis | Other Features |
|---|---|
| Fibroadenoma | Oval/lobulated, circumscribed, homogeneous or dark septations; most common |
| Mucinous carcinoma | May be oval, T2 hyperintense; malignant — look for indistinct margin |
| IDC with mucinous features | T2 hyperintense despite malignancy |
| Intramammary lymph node | Oval, circumscribed, fatty hilum |
| Papilloma | T2 hyperintense, intraductal |
Board Pearl
T2 hyperintensity alone does NOT equal benignity. Mucinous carcinoma and IDC can be T2 hyperintense. The combination of all four benign-favoring features is required.
Pitfalls
- Central necrosis in IDC may appear T2 bright — the exception is not “uniformly bright” and will have other suspicious features
- High-grade tumors occasionally have T2 hyperintensity