Lipoma
Supplemental Studies
Immunohistology
- Mature fat cells are S100 positive
- See specific variant entries for other staining patterns
| MDM2 | CDK4 | p16 | |
| Atypical lipomatous tumor | 45-100% | 84-92% | 78-97% |
| Dedifferentiated liposarcoma | 55-95 | 90-100 | 90 |
| Myxoid / round cell liposarcoma | 0-4 | 0-4 | 0 |
| Pleomorphic liposarcoma | 0 | 0 | 0 |
| Lipoma | 0-4 | 0-2 | 0 |
| Spindle cell and pleomorphic lipoma | 0-25 | 0-6 | 20 |
| Angiomyolipoma | 0 | 0 | |
| Hibernoma | 0 | 0 | positive, variable |
| Lipoblastoma | 0 (1 case) | 0 (1 case) | positive (1 case) |
Genetic analysis
- About half to 3/4 of ordinary lipomas have chromosomal abnormalities
- Most involve 12q13-15
- 6p21-23 and 13q12-14 may also be involved
- See specific variants for other abnormalities
| MDM2 FISH | MDM2 QPCR | CDK4 FISH | CDK4 QPCR | |
| Atypical lipomatous tumor | 90-100% | 72-100% | 75-100% | 69-100% |
| Dedifferentiated liposarcoma | 100% | 100% | 100% | 100% |
| Myxoid liposarcoma | 20% | |||
| Spindle cell / pleomorphic lipoma | Negative | Negative | Negative | Negative |
| Angiolipoma | Negative | |||
| Lipoma, NOS | Negative | Negative | Negative | Negative |
| Sarcomas | 0-40% | 0% | 0% | 0% |
