Endothelial tumors

Blood vessel tumors


Hemangiomas are categorised based on morphology and location. If the bewildering array of different types causes your eyes to involuntary roll, you are not alone.

Cavernous hemangioma

Capillary hemangioma

Capillary like vascular channels

Often in lobules

Not exophytic

Inflammed lobular capillary hemangioma

Exophytic tumor

often ulcerated and the inflammation is from ulceration and thus is on the surface.

lobular arrangement of capillary like vascular channels

Usually has a feeder vessel for each lobule.

Overlying epidernal hyperplasia and hyperkeratosis is common.

Mixed capillary - cavernous hemangioma


Spindle cell hemangioma

Epithelioid hemangioma


Infiltrative hemangioma

These invariably have adipocytes with the vascular channels.


Epithelioid hemangioendothelioma

Retiform hemangioendothelioma

Kaposiform hemangioendothelioma



Lymphatic tumors





Fibrous Tumors

Solitary fibrous tumor

In humans Solitary fibrous tumor (SFT) is a mesenchymal tumor with uncertain differentiation and intermediate malignant potential. SFTs can arise at any location (pleural or extrapleural) and display a wide histopathological spectrum, frequently with hemangiopericytoma‐like vessels. Several other histological patterns have also been described, including round cell, giant‐cell‐containing, epithelioid, myxoid, fat‐forming, pleomorphic and dedifferentiated variants.3,8,9,22–30 Many of the histological variants reveal a focal patternless architecture, and variably fibro‐collagenous stroma.1–9,22–30 NAB2‐STAT6
was discovered as a novel fusion gene of SFTs, and STAT6 immunoexpression has been established as a surrogate marker of the NAB2‐STAT6 gene fusion, expression of this protein representing a very sensitive and specific diagnostic tool.
There are benign and malignant types.

Desmoid type Fibromatosis

In humans, Desmoid-type fibromatosis is a locally aggressive neoplasm composed of long sweeping fascicles of bland fibroblasts/myofibroblasts.
tumors are composed of a proliferation of bland fibroblasts/myofibroblasts arranged in long sweeping
fascicles admixed with thin-walled blood vessels. However,
variable histologies are occasionally seen, including dense
keloidal collagen, myxoid zones, and areas reminiscent of
nodular fasciitis.1,8
Fascicles extend past a 100x field
staghorn vessel,
myxoid, keloidal,
nodular fasciitis-like

Inflammatory myofibroblastic tumour (IMT)

In humans these tumors have a consistent gene fusion, MYH9–USP6
Ellies tumour!
C. Knight; E. Fan; R. Riis; S. McDonough (2009) Inflammatory Myofibroblastic Tumors in Two Dogs Vet Pathol 46: 273-276.
Synonyms include inflammatory fibrosarcoma, inflammatory pseudotumour
Fibroblastic cells and lymphocytes and plasma cells. Not histiocytes except dendritic cells around vessels.
Well demarcated
IHC profile includes
100% of spindle cells vimentin diffuse cytoplasmic staining
100% of spindle cells Claponin
20% SMA positive cytoplasmic and surface
20% desmin predominantly surface
Negative – panCK, GFAP, s100, Melan A, CD18,
Both did well with removal

Nodular fasciitis

In humans there is an “abundance of plump spindle and stellate fibroblasts arranged in an intercellular matrix that may be relatively scant or myxoid”

Price EB Jr, Silliphant WM, Shuman R. Nodular fasciitis: a clinicopathologic analysis of 65 cases. Am J Clin Pathol. 1961;35: 122-36
Shimizu S, Hashimoto H, Enjoji M. Nodular fasciitis: an analysis of 250 patients. Pathology. 1984 Apr;16(2):161-6.

Fibroma and Fibrosarcoma

Conventional Fibroma and Fibrosarcoma


Keloidal Fibroma and Fibrosarcoma


Myofibroblastic Fibroma and Fibrosarcoma


Myxoma and Myxosarcoma


Inflammatory Fibroblastic Tumor




Lipomas, liposarcomas and hibernoma







Spindle cell lipoma

Infiltrative lipoma

Infiltrative lipomas are just like regular lipoma but they infiltrate surrounding tissue

Infiltrative lipoma (JAVMA 205: 322)
65% survive 12 months
Hind limb, bad prognosis
recurrence common

Infiltrative angiolipoma

Intermuscular lipoma



Liposarcomas have either neoplastic mature lipocytes and or lipoblasts.

Liposarcomas are vimentin +, UCP1+, and variably S100+, SMA+, desmin+, and myogenin+,

Baez JL et al (2004)

56 dogs with liposarcoma, 6 visceral 50 skin and soft tissues
Median survival 694 days
Cause of death was known in 25, of which 10 were tumor related and 1 was metastatic (radiographs) and 2 of 8 with skin and soft tissue tumors had ultrasound mets to liver and spleen
Some had mets to spleen and liver


Well differentiated liposarcoma

Little spindle cell formation
Lipocytes and lipoblasts
MDM2 postive

Dedifferentiated liposarcoma

Spindle cells with rare lipid vacuoles
Rare type
MDM2 positive

Myxoid liposarcoma

Myxosarcoma like regions
Least common of 3 main types
MDM2 negative

Pleomorphic liposarcoma

Marked cellular pleomorphism
Giant cells
Little lipid
MDM2 negative


Avallone G, Roccabianca P, Crippa L, Lepri E, Brunetti B, Bernardini C, Forni M, Olandese A, Sarli G. Histological Classification and Immunohistochemical Evaluation of MDM2 and CDK4 Expression in Canine Liposarcoma. Vet Pathol. 2016; 53: 773-780.

Baez JL, Hendrick MJ, Shofer FS, Goldkamp C, Sorenmo KU. Liposarcomas in dogs: 56 cases (1989-2000). J Am Vet Med Assoc. 2004; 224: 887-891.

Doria-Torra G, Martínez J, Domingo M, Vidaña B, Isidoro-Ayza M, Casanova MI, Vidal E. Liposarcoma in animals: literature review and case report in a domestic pig (Sus scrofa). J Vet Diagn Invest. 2015; 27: 196-202.


Perivascular wall tumors