Lipoma

Benign tumors showing differentiation to mature adipocytes.

Gross Appearance:
•Present in the dermis or subcutaneous tissue 
•Size varies from less than 1 cm to up to 30 cm
•Most are soft, very well circumscribed subcutaneous masses
•Occasional lipomas may also contain other tissues such as cartilage (chondrolipoma), blood vessels (angiolipoma) and collagen (fibrolipoma). 
•More common in obese dogs.
•Usually surrounded by a thin connective tissue capsule rich in small blood vessels
•Color varies from white to deep yellow
•In large tumors or tumors subjected to trauma, foci of necrosis may be present
•Tumor floats when places in water or 10% neutral buffered formalin.


Histology:
•Histopathology of normal adipose tissue 
•Diffentiated cells are spherical or polygonal 
•Entire cytoplasm is absent
•Cells show little pleomorphism 
•Nuclei are inconspicuous
•Connective tissue and vessels are present within the peripheral capsule and the interlobular trabeculae
•Foci of necrosis show infiltration by foamy macrophages and inflammatory cells and areas of fibrosis

Cytology:

               Sex Distribution (N=7201)

Sex Status

Percent

Male

(45.0%)

39.3%
intact

(28.1%)

 18.7
neutered

(16.9%)

 20.5
Female

(55.0%)

60.7%
intact

(23.9%)

 23.8
neutered

(31.1%)

 36.9
(normal sex distribution)

 
Anatomic Location (N=6815)
Site

Percent

Thorax  33.6
Abdomen  18.1
Hindlimb  15.3
Forelimb  12.5
Multiple  7.8
Neck  3.8
Head  3.0
Back  2.4
Perineum  2.3
Tail  1.2
 


Copyright © 2000 - University of Pennsylvania School of Veterinary Medicine
Faculty: Michael H. Goldschmidt, BVMS & Patricia Mcmanus,VMD, PhD
Student: Kyle Goldschmidt
Comments: goldsch@vet.upenn.edu