Peer-reviewed veterinary case report
How to identify spindle cell lipoma in dogs by cytology
By Santos, Marta et al.·Published in Veterinary medicine and science·2025·ICBAS-School of Medicine and Biomedical Sciences·View original on PubMed →
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Original publication title: Cytology and Differential Diagnosis of Canine Spindle Cell Lipoma.
- Species:
- dog
Plain-English summary
A 3-year-old dog was found to have a spindle cell lipoma, a rare type of benign tumor made up of fat and spindle-shaped cells. The dog's tumor was examined through a needle sample, which showed a mix of fat cells and unusual spindle cells, but no signs of cancer. After two years of follow-up, the tumor did not return or spread, confirming it was benign. This case emphasizes the importance of accurate diagnosis to avoid mistaking this type of tumor for a more serious condition.
People also search for: dog lump diagnosis · spindle cell lipoma in dogs · benign tumors in dogs · dog tumor follow-up care
Abstract
Benign lipomatous tumours in dogs included the very common lipoma and its rare variants, such as spindle cell lipoma. Canine spindle cell lipomas have been seldom described, and their histopathological clues included the concomitant presence of mature adipose tissue and a population of spindle cells immersed in a fibromyxoid matrix. The cytological features of this lipocytic tumour have never been described in veterinary medicine. Herein, a cytological description of a spindle cell lipoma in a 3-year-old dog, for which 2 years follow-up data were available is presented. Cytological smears were characterized by a mixture of mature adipocytes and pleomorphic spindle cells, including multinucleated cells in association with blood vessels, thick collagen fibres and small amount of mucinous matrix. On histopathology, the tumour exhibited some papillary growth and was composed mostly by mature adipose tissue enriched in blood vessels and a smaller number of spindle cells immersed in a matrix with ropey collagen and myxoid substance. Spindle cells were positive to vimentin and negative for muscle, neural and endothelial markers. The cytological findings in the present case paralleled descriptions for human spindle cell and pleomorphic lipomas, which are related variants. The abundance of the mature adipose tissue component and unremarkable follow-up with no recurrence or metastases documented were compatible with a benign tumour. This case highlighted that a prompt diagnosis of sarcoma should be avoided when a cytological sample from a subcutaneous mass in a dog is characterized by a mixture of mature adipocytes and spindle cells in association with collagen bundles.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41091537/