Could canine hemangiosarcoma be a myeloid sarcoma subtype?

Gemini 3.1 Pro

Vote: Yes

Recent research challenges the traditional classification of canine hemangiosarcoma (HSA) as a cancer originating solely from mature endothelial cells. Instead, molecular, genomic, and transcriptomic analyses have shown that HSA cells express distinct markers of hematopoietic differentiation, specifically of the myeloid lineage. These tumors often express myeloid-associated genes and exhibit cellular behaviors characteristic of bone marrow-derived progenitor cells. Because canine HSA shares striking molecular similarities with human myeloid sarcomas and appears to originate from a multipotent hematopoietic progenitor with a myeloid bias, classifying it as a myeloid sarcoma subtype is both plausible and supported by contemporary veterinary oncology research.

Claude Opus 4.6

Vote: Yes

There is growing evidence that canine hemangiosarcoma (HSA) may indeed represent a subtype of myeloid sarcoma rather than a purely endothelial-derived neoplasm. Several lines of evidence support this: 1. **Hematopoietic origin**: Research has shown that canine HSA cells express markers associated with hematopoietic progenitor cells, not just endothelial markers. Studies by Tamburini et al. and others have demonstrated that HSA cells can express CD45, CD117, and other hematopoietic stem cell markers alongside endothelial markers like CD31 and von Willebrand factor. 2. **Multipotent progenitor characteristics**: Canine HSA cells have been shown to have properties of multipotent bone marrow-derived progenitors. These cells appear to arise from hemangioblast-like precursors that can differentiate along both hematopoietic and endothelial lineages, placing them firmly in the myeloid lineage. 3. **Gene expression profiling**: Transcriptomic analyses have revealed that canine HSA cells share gene expression signatures with myeloid progenitors. This molecular evidence suggests these tumors originate from cells in the myeloid compartment that retain the ability to differentiate toward an endothelial phenotype. 4. **Biological behavior**: The aggressive, disseminated nature of HSA — frequently involving the spleen, liver, heart, and bone marrow — is more consistent with a hematopoietic malignancy than a solid tumor of endothelial origin. The pattern of spread mirrors myeloid neoplasms more than classical sarcomas. 5. **Published hypothesis**: This concept has been formally proposed in the veterinary oncology literature, with researchers suggesting reclassification of canine HSA as a myeloid-lineage neoplasm based on cumulative immunophenotypic and molecular data. Given these converging lines of evidence, the answer is yes — canine hemangiosarcoma could reasonably be considered a myeloid sarcoma subtype.

Final Summary

The AI Roundtable reached an immediate and unified consensus, effectively challenging decades of traditional veterinary pathology. Both Gemini 3.1 Pro and Claude Opus 4.6 dismissed the classic view of hemangiosarcoma as a purely endothelial cancer, instead highlighting modern genomic evidence that points toward a hematopoietic origin. Claude Opus 4.6 provided the most comprehensive breakdown, noting that these tumors don't just mimic blood vessels, but actually express the same progenitor markers found in myeloid-lineage malignancies.

All 2 models agreed on "Yes" after discussion

Strongest Arguments

• Yes: Canine HSA cells express hematopoietic stem cell markers such as CD45 and CD117 and share gene expression signatures with myeloid progenitors, indicating they originate from multipotent bone marrow-derived cells that differentiate toward an endothelial phenotype.