Published in Frontiers in Veterinary Science, this case report documents a diagnostically challenging and biologically aggressive vascular tumor arising from lymphatic endothelium. Angiosarcomas in dogs are poorly characterized, and LAS represents an uncommon subtype that can be distinguished by expression of markers such as PROX-1 and LYVE-1.
The patient, a 10-year-old male Labrador retriever, presented with a progressively enlarging 6-cm cutaneous mass caudal to the left elbow, with palpable extensions over the triceps and regional lymphadenopathy. Initial cytology favored an epithelial neoplasm—possibly metastatic or mixed—complicating early diagnostic interpretation.
An incisional biopsy revealed a well-differentiated angiosarcoma displaying features consistent with composite hemangioendothelioma, a rare vascular tumor subtype in humans characterized by combined retiform and epithelioid elements. Immunohistochemistry supported a diagnosis of LAS through positive labeling for vimentin, CD31, von Willebrand factor (vWf), and PROX-1.
Staging revealed no distant metastases. The dog underwent forelimb amputation with lymph node removal, followed by doxorubicin chemotherapy due to evidence of local metastasis at diagnosis. Despite treatment, the tumor recurred locally after 7 months, without systemic spread—consistent with the locally aggressive but infrequently metastatic profile described in human CHE cases.
This case underscores the challenges of diagnosing vascular tumors that mimic epithelial neoplasms cytologically. The combination of morphological evaluation and targeted immunohistochemistry proved critical for accurate classification. It also provides the first detailed description of a canine LAS with CHE-like features, expanding comparative oncology knowledge.
Source: Cook, M., Lorbach, J., & colleagues (2021). Case Report: Cutaneous Pleomorphic Lymphangiosarcoma in a Dog Exhibiting Features of Human Composite Hemangioendothelioma. Frontiers in Veterinary Science. Published October 22, 2021.
