Spindle Cell Lipoma in Dogs.

Area of Science:

• Veterinary Pathology
• Surgical Oncology
• Comparative Oncology

Background:

• Spindle cell lipoma (SCL) is a rare benign adipose tumor.
• SCL can be mistaken for soft tissue sarcoma (STS).
• Histopathological characterization of canine SCL is limited.

Purpose of the Study:

• To describe the histopathological features of canine SCL.
• To differentiate SCL from other spindle cell tumors in dogs.

Main Methods:

• Histopathological examination of 6 canine SCLs.
• Immunohistochemical analysis for vimentin, S100 protein, smooth muscle actin, factor VIII-related antigen, and MDM2.
• Sudan IV staining for lipid content.

Main Results:

• All SCLs were subcutaneous, composed of bland spindle cells with vacuolated cytoplasm, ropey collagen, and myxoid matrix.
• Mature adipocytes were sparse (<10%) or absent.
• Immunohistochemistry showed vimentin positivity and negativity for S100, SMA, FVIII-RA, and MDM2.
• Low mitotic activity (0.17/HPF).

Conclusions:

• Canine SCL exhibits distinct histopathological features.
• Immunohistochemistry is crucial for differentiating SCL from STS.
• Further research is needed on the biological behavior of canine SCL.