Hemangioma

A benign neoplasm that shows differentiation to vascular endothelium and the formation of blood vessels.

Gross Appearance:
•Those in the superficial dermis are usually elevated and blue to purple and the overlying epidermis may be ulcerated and bleeding
•Those in the deep dermis and subcutis are usually larger with no abnormalities of the overlying skin
•Dark red
•Well demarcated
•Encapsulated

Histology:
•Plump endothelial cells line vascular channels
•Small or inconspicuous vascular lumina
•Little nuclear atypia
•Few mitotic figures
or
•Lumina are large
•Lumina are filled with erythrocytes and plasma
•Vascular channels are lined by flattened endothelial cells
•Neoplastic endothelium is supported by a fibrous stroma
•Occasionally lumina are filled with thrombi

Features that suggest progression from benign to malignant:
•Increased cellularity
•Larger and more prominant nuclei and nucleoli
•Evagination of the nucleus into the vascular lumina
•Increased mitotic activity
•Proliferation of fusiform cells without the formation of true vascular lumina
•Presence of erythrocytes between the cells

Breeds At Increased Risk
Breed	Odds Ratio	95% Confidence Limit	Probability
Bedlington Terrier	5.703	1.790 - 18.165	0.018
Bloodhound	4.897	2.297 - 10.440	0.001
Briard	4.757	1.944 - 11.639	0.005
Airedale Terrier	4.112	2.880 - 5.869	0.001
Gordon Setter	3.700	1.969 - 6.955	0.001
Boxer	2.932	2.386 - 3.603	0.001
Giant Schnauzer	2.687	1.106 - 6.582	0.042
Greyhound	2.448	1.306 - 4.586	0.001
Golden Retriever	2.020	1.734 - 2.353	0.001
English Springer Spaniel	1.600	1.162 - 2.203	0.006
German Shepherd	1.556	1.267 - 1.910	0.001

Breeds At Decreased Risk
Breed	Odds Ratio	95% Confidence Limit	Probability
Doberman Pinscher	0.665	0.468 - 0.945	0.021
Miniature Poodle	0.531	0.354 - 0.795	0.001
Cocker Spaniel	0.372	0.251 - 0.553	0.001
Collie	0.363	0.151 - 0.875	0.013
Yorkshire Terrier	0.332	0.149 - 0.741	0.003
Miniature Schnauzer	0.327	0.163 - 0.656	0.001
Rottweiler	0.233	0.111 - 0.490	0.001
Shar-Pei	0.116	0.016 - 0.824	0.003

Sex Distribution (N=1477)

Sex

Status

Percent

Male	(45.0%)
46.4%

intact

(28.1%)

29.9

neutered

(16.9%)

16.5

Female	(55.0%)
53.6%

intact

(23.9%)

20.4

neutered

(31.1%)

33.2

(normal sex distribution)

Anatomic Location (N=1337)
Site	Percent
Hindlimb	24.2
Forelimb	14.7
Thorax	12.4
Abdomen	10.2
Neck	9.0
Head	8.7
Back	8.6
Multiple	4.9
Tail	3.8
Perineum	2.2
Scrotum	1.3