Lesion | Clinical | Microscopy | IHC | Cytogenetics |
SCL | Middle age males, posterior back, neck, shoulders | Bland to atypical, +/− lipoblasts, ropey collagen, myxoid stroma | CD34+; SMA+; pRb−; desmin− ; MDM2−/+; CDK4−; p16−/+ | Deletion of 13q14; no amplification of MDM2 or CDK4 |
MTMF | Groin, trunk, lower extremities | Well-circumscribed, bland, diffuse collagenous stroma | CD34+; desmin+; SMA+; EMA+; pRb−; MDM2−; CDK4−; p16− | Deletion of 13q14; no amplification of MDM2 or CDK4 |
CA | Inguinal region | Moderately cellular, bland, mitoses in females, wispy collagen, thin and thick- walled vessels | CD34+; desmin+; SMA+; EMA+; ER/PR+; pRb−; MDM2−; CDK4−; p16− | Deletion of 13q14; no amplification of MDM2 or CDK4 |
ASCLT | Adult males, limbs and limb girdles | Ill-defined, variable: cellularity, atypia, fat cell size; lipoblasts in 50%, multinucleated cells | CD34+; desmin+; S100+; pRb+ or – in 50%; MDM2−; CDK4−; p16− | Deletion of 13q14 in 50%–60%; no amplification of MDM2 or CDK4 |
ALT | Anywhere deep-seated (retroperitoneum, mediastinum) except posterior back, neck, shoulders | Adipocyte size variation, low, cellularity, mild-to-moderate atypical hyperchromatic spindle cells, lipoblasts, rare mitoses, myxoid stroma | CD34−; desmin−; pRb+; MDM2+; CDK4+; p16+ | Amplification of MDM2 and CDK4 |
DDL | Middle/old age, retroperitoneum, extremities, paratesticular | Sharp demarcation between well-differentiated and dedifferentiated areas; moderate-to-high cellularity of spindle cells, myxoid stroma, heterologous elements | CD34−/+; desmin focal+, SMA focal+; pRb+; MDM2+; CDK4+; p16+ | Amplification of MDM2 and CDK4 |
+, positive; −/+, mainly negative, but can be positive; +/−, mainly positive, but can be negative.
ALT, atypical lipomatous tumour; ASCLT, atypical spindle cell lipomatous tumour; CA, cellular angiofibroma; DDL, dedifferentiated liposarcoma; EMA, epithelial membrane antigen; ER, oestrogen receptor; IHC, immunohistochemistry; MTMF, mammary-type myofibroblastoma; PR, progesterone receptor; pRb, retinoblastoma protein; SCL, spindle cell lipoma; SMA, smooth muscle actin.