Lipoma

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

• Benign.
• Several variants exist.
  • Angiolipoma - one of the (classically) painful skin lesions.

Microscopic

Features:

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

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, esp. chickenwire-like vessels, fibrous septae.
• Benign adipose tissue.

Images:

• Lipoma - cardiac (ahajournals.org).

Variants

Angiolipoma

• A painful skin lesion.

Microscopic:

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

DDx:

• Liposarcoma.

Myolipoma

General:

• May mimic a sarcoma radiologically.
• Extremely rare.
• Usually large ~ 16 cm.

Microscopic:

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

Note:

• If skeletal muscle is present consider intramuscular lipoma.

IHC:

• Actin +ve.
• Desmin +ve.

Images:

• Myolipoma (nih.gov).
• Myolipoma (webpathology.com).

Images

• 

  Mature fat. (WC)

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

• Adipocytic tumours.