Lipoma

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Lipoma is a benign adipocytic tumour.

Lipoma
Diagnosis in short

Mature adipose tissue (lipoma). H&E stain.

LM mature adipocytes
LM DDx liposarcoma, benign fat
IHC S-100 +ve
Site soft tissue

Prevalence common
Prognosis benign

General

Microscopic

Features:

  • Collection of mature adipocytes.
    • Variation of size may be seen -- should prompt a search for lipoblasts.[1]

Notes:

  • Microscopically not definitely distinguishable from mature clump of fat.
    • The lesion must be labeled lipoma (by the clinican) to be signed-out as such.

DDx:

  • Liposarcoma - increased number of blood vessels,[2] esp. chickenwire-like vessels, fibrous septae.
  • Benign adipose tissue.

Images:

Variants

Angiolipoma

Microscopic:

  • Numerous blood vessels present.
  • +/-Microthrombi.

DDx:

Myolipoma

General:

  • May mimic a sarcoma radiologically.[4]
  • Extremely rare.[5]
  • Usually large ~ 16 cm.[6]

Microscopic:[5]

  • Mature adipose tissue.
  • Benign smooth muscle - usually ~ 2x amount of fat.

Note:

  • If skeletal muscle is present consider intramuscular lipoma.[7]

IHC:[5]

  • Actin +ve.
  • Desmin +ve.

Images:

Images

Sign out

SUBCUTANEOUS TISSUE ("LIPOMA"), LEFT AXILLA, EXCISION: 
- MATURE ADIPOSE TISSUE CONSISTENT WITH LIPOMA.
LESION ("LIPOMA"), SPERMATIC CORD (LATERALITY NOT SPECIFIED), EXCISION: 
- MATURE ADIPOSE TISSUE CONSISTENT WITH LIPOMA.

Colonic lipoma (clinically suspected)

B. SIGMOID COLON AT 55 CM, BIOPSY:
- COLORECTAL-TYPE MUCOSA WITHIN NORMAL LIMITS WITH A SMALL AMOUNT OF SUBMUCOSAL
  ADIPOSE TISSUE; COMPATIBLE WITH CLINICAL IMPRESSION OF LIPOMA.

Mirco

The sections show mature adipocytes. There is no increase in vascularity. No thick fibrous septa are present.

See also

References

  1. Mentzel, T.; Fletcher, CD. (1995). "Lipomatous tumours of soft tissues: an update.". Virchows Arch 427 (4): 353-63. PMID 8548119.
  2. Yang, YJ.; Damron, TA.; Cohen, H.; Hojnowski, L. (Oct 2001). "Distinction of well-differentiated liposarcoma from lipoma in two patients with multiple well-differentiated fatty masses.". Skeletal Radiol 30 (10): 584-9. doi:10.1007/s002560100395. PMID 11685482.
  3. Friedberg, MK.; Chang, IL.; Silverman, NH.; Ramamoorthy, C.; Chan, FP. (May 2006). "Images in cardiovascular medicine. Near sudden death from cardiac lipoma in an adolescent.". Circulation 113 (21): e778-9. doi:10.1161/CIRCULATIONAHA.105.589630. PMID 16735681. http://circ.ahajournals.org/content/113/21/e778.full.
  4. URL: http://www.webmedcentral.com/article_view/1878. Accessed on: 14 March 2013.
  5. 5.0 5.1 5.2 Murphey, MD.; Carroll, JF.; Flemming, DJ.; Pope, TL.; Gannon, FH.; Kransdorf, MJ.. "From the archives of the AFIP: benign musculoskeletal lipomatous lesions.". Radiographics 24 (5): 1433-66. doi:10.1148/rg.245045120. PMID 15371618. http://radiographics.rsna.org/content/24/5/1433.long.
  6. Meis, JM.; Enzinger, FM. (Feb 1991). "Myolipoma of soft tissue.". Am J Surg Pathol 15 (2): 121-5. PMID 1703396.
  7. URL: http://surgpathcriteria.stanford.edu/softfat/lipoma/intramuscular_lipoma.html. Accessed on: 14 March 2013.
  8. Lee, YS.; Park, SE.; Lee, JU.; Choi, ES.. "MRI of a subcutaneous myolipoma in the ankle: a case report.". Korean J Radiol 12 (5): 641-5. doi:10.3348/kjr.2011.12.5.641. PMC 3168809. PMID 21927569. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3168809/.