Types

 superficial lipomas (cutaneous lipoma)
 deep lipoma

• intramuscular lipoma
• tendon sheath lipoma
• lombosacral lipoma
• intraneural fibrolipoma and perineural fibrolipoma
• retroperitoneal lipomas

Variants

 chondroid lipoma
 sclerotic lipoma
 spindle cell lipoma/pleomorphic lipoma

Cytogenetics

 More than half the cases studied show an abnormal karyotype, mostly balanced translocation, as single abnormality.

 12q13-15 rearrangements

• target gene: HMGA2 (HMGIC)
• with 3q27-28 (LPP from LIMs family)

 13q11-q22

 6p21-23

• target gene: HMG1A

 t(1;8)(q32;q22-q23) (1q32 and 8q23-8q23) (#11943344#)

Molecular biology

 sporadic lipomas

• HMGA2/RDC1 fusion protein expression in lipomas as the result of chromosome aberrations involving 2q35-37 and 12q13-15. (Fusion of RDC1 with HMGA2 in lipomas)

 predisposition to lipomas

• HMGA2: Constitutional rearrangement of HMGA2 in a phenotype including extreme somatic overgrowth, advanced endochondral bone and dental ages, a cerebellar tumor, and multiple lipomas. (#15593017#)

Differential diagnosis

 atypical liponatous tumor (well-differentiated liposarcoma)

See also

 Tumors

• soft tissue tumors
  • adipose tissue tumors
    • benign adipose tissue tumors