Fibrosarcoma (FIBROBLASTIC SARCOMA)

• Malignant mesenchymal tumor derived from fibrous CT and characterized by presence of immature proliferating fibroblasts or undifferentiated anaplastic spindle cells in storiform pattern
• Fibrosarcoma is found most often in dog and cat. Although they do occur in all species.

Mostly develo[ed in adult and aged animals,occasionally will be found as young as six month of age or even younger

No breed predisposition or sex prevalence is found in domestic animal.

Sites:

• Most common sites in dog-skin and subcutis, oral cavity and nasal cavity
• In cats often in subcutis.
• New plasma can be found in any location in the body, Although internal sites are uncommon.

Gross :

• They are of variable size and some are very large.
• They are usually irregular and nodular in shape, poorly demarcated and non-encapsulated.
• Consistency is firm or fleshy , with soft or fleshy , friable areas .
• When they involve skin and mucous membrane, the surface are often ulcerated and secondarily infected
• On the cut surface new plasma is lobulated, homogeneous,opaque and greyish white and may exhibit striae.
• Reddish brown areas of haemorrhages and yellow areas of necrosis are common.

Microscopic:

• Basic Pattern of fibrosarcoma consist of interwoven bundles of immature fibroblast and moderate no. collagenous fibres
• Tumor is more cellular than fibroma
• Some fibrosarcoma have variable amount of mucinous grounds substance
• Tumor cells are usually fusiform butr maybe stellate in shape
• Undifferentiated tumor may present multinucleated giant cell and cells bizarre shapes
• Nuclei are elongated or ovule and hyperchromatic.
• Mitotic figures are common

• Fibrosarcoma are highly vascular , but blood vessels are poor;y formed and haemorrhages are common.
• Ischemic necrosis of tumor tissue, inflammation and edema are common

Growth and metastasis:

• Most fibrosarcoma demonstrate rapid, infiltrative growth
• They often recur after surgical removal, but metastasis occur in less than one quarter of cases

      Fibrosarcoma are divided into :

1. Highly malignant :

 Fibrosarcoma with many mitotic figure and marked nuclear pleomorphism

2. Low grade malignancy:

Fibrosarcoma with few mitotic figure and abandoned collagen production