Table 1

Fatty tumours with spindle cells

LesionClinicalMicroscopyIHCCytogenetics
SCLMiddle age males, posterior back, neck, shouldersBland to atypical, +/− lipoblasts, ropey collagen, myxoid stromaCD34+; SMA+; pRb−; desmin− ; MDM2−/+;
CDK4−; p16−/+
Deletion of 13q14; no amplification of MDM2 or CDK4
MTMFGroin, trunk, lower extremitiesWell-circumscribed, bland, diffuse collagenous stromaCD34+; desmin+; SMA+; EMA+; pRb−; MDM2−; CDK4−; p16−Deletion of 13q14; no amplification of MDM2 or CDK4
CAInguinal regionModerately cellular, bland, mitoses in females, wispy collagen, thin and thick- walled vesselsCD34+; desmin+; SMA+; EMA+; ER/PR+; pRb−; MDM2−; CDK4−; p16−Deletion of 13q14; no amplification of MDM2 or CDK4
ASCLTAdult males, limbs and limb girdlesIll-defined, variable: cellularity, atypia, fat cell size; lipoblasts in 50%, multinucleated cellsCD34+; desmin+; S100+; pRb+ or – in 50%;
MDM2−; CDK4−; p16−
Deletion of 13q14 in 50%–60%; no amplification of MDM2 or CDK4
ALTAnywhere deep-seated (retroperitoneum, mediastinum) except posterior back, neck, shouldersAdipocyte size variation, low, cellularity, mild-to-moderate atypical hyperchromatic spindle cells, lipoblasts, rare mitoses, myxoid stromaCD34−; desmin−; pRb+; MDM2+; CDK4+; p16+Amplification of MDM2 and CDK4
DDLMiddle/old age, retroperitoneum, extremities, paratesticularSharp demarcation between well-differentiated and dedifferentiated areas; moderate-to-high cellularity of spindle cells, myxoid stroma, heterologous elementsCD34−/+; 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.