Soft tissue

Adipose tissue tumors

Lipoma and variants


Topic Completed: 1 August 2012

Minor changes: 3 September 2021

Copyright: 2002-2021,, Inc.

PubMed Search: Lipoma [title] soft tissue

Vijay Shankar, M.D.
Page views in 2020: 23,274
Page views in 2021 to date: 28,106
Cite this page: Shankar V. Lipoma. website. Accessed October 16th, 2021.
Definition / general
  • Benign tumor composed of mature white adipocytes with uniform nuclei resembling normal white fat
  • Most common mesenchymal and soft tissue tumor (100x more common than liposarcoma)
  • Most common soft tissue tumor - 16% of all mesenchymal neoplasms
  • Adults, age 40+
  • No gender or ethnic preference
  • Rare in children
  • Associated with obesity
  • Multiple lipomas: 5%, more common in women, often familial, associated with neurofibromatosis, multiple endocrine neoplasia syndromes, Bannayan syndrome (macrocephaly, hemangiomas and lipomas, Wikipedia)
  • Usually trunk, back, shoulder, neck, proximal extremities
  • Rare on hands, feet, face, lower leg, retroperitoneum
  • Usually subcutaneous (liposarcomas are usually deep seated)
  • Unusual sites include oral cavity, pancreas, breast, intestines
Clinical features
  • Relatively static growth after initial growth period
  • Does not regress even with starvation
  • Becomes hard after application of ice
  • Lipoma with prominent bundles of mature fibrous tissue traversing fatty lobules
  • Not a WHO diagnosis
  • Also present in head and neck (Contemp Clin Dent 2012;3:S112)
  • Fibrovascular polyps of esophagus are also called fibrolipomas
  • See also lipomatosis of nerve
Case reports
  • Benign, but 1 - 4% recur
  • Excision is adequate treatment
Clinical images

Contributed by Mark R. Wick, M.D.


Images hosted on other servers:

Right breast mass

Intraoperative parotid tumor

Gross description
  • Bright yellow homogeneous fat with fine fibrous capsule (superficial lesions only) and trabeculae
  • May be very large (particularly if deep)
  • Greasy cut surface
Gross images

Contributed by Mark R. Wick, M.D.


Spindle cell type

Fatty mass with surgery related hemorrhage

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After resection

Chest wall giant lipoma

Encapsulated cardiac mass

Encapsulated mass

Microscopic (histologic) description
  • Lipoma with fibrous tissue component
Microscopic (histologic) description
  • Mature white adipose tissue without atypia
  • 2 - 5x variation in cell size (more than normal white adipose tissue), with obvious large cells up to 300 microns
  • Cytoplasmic vacuoles are relatively uniform
  • May have intranuclear vacuoles, thickened fibrous septa in buttocks, foot or hand
  • May contain areas of fat necrosis with histiocytes, infarct or calcification
  • Rarely contains bone or cartilage
  • No mitotic figures
  • Note: diagnosis of lipoma requires presence of a mass
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.

Chondroid type

Fibrohistiocytic type

Spindle cell type, CD34

Spindle cell type

Intramuscular type


Pleomorphic superficial type

Normal adult fat cells

Mature adipose tissue and dense bands of fibrosis

Contributed by Charanjeet Singh, M.D.

Myxoid change

Cytology images

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Positive stains
Electron microscopy description
  • Univacuolar mature adipocytes that compress peripheral nuclei (Cancer 1982;50:102), pinocytotic vessels, cells are surrounded by external lamina
Molecular / cytogenetics description
  • 55% - 75% of solitary lipomas with cytogenetic abnormalities have rearrangements of HMGA2 / HMGIC at 12q13-15, although no associated clinicopathologic features are associated with the resulting fusion transcripts (Anticancer Res 2008;28:535, J Biomed Biotechnol 2011;2011:524067)
  • Marker ring or giant chromosomes are extremely rare
  • Multiple lipomas usually have normal phenotype
Molecular / cytogenetics images

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Schematic of HMGA2 and LPP

Differential diagnosis
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