Well-Differentiated, Low-Grade Subcutaneous Liposarcoma With a Fatal Outcome in a Dog

A 10-year-old intact male Rottweiler was presented with a large, rapidly growing subcutaneous mass on the right thoracic limb. Physical examination revealed a firm, raised, non-ulcerated mass extending from the proximal scapula to the distal humerus. Cytological evaluation identified a highly cellular population of vacuolated cells with marked anisocytosis and anisokaryosis, consistent with a lipid-rich mesenchymal neoplasm. Histopathology of incisional biopsies confirmed a well-differentiated, low-grade subcutaneous liposarcoma. The owner declined therapeutic and surgical treatments. The dog died 3 months after diagnosis, with clinical signs suggestive of metastatic disease. This case highlights the importance of comprehensive tumour assessment for accurate grading, staging and effective management of canine soft tissue sarcomas, including liposarcomas. Liposarcoma should be considered a differential diagnosis for subcutaneous masses in the proximal limbs of dogs. Early diagnosis, accurate grading, complete staging and prompt surgical intervention, including limb amputation if warranted, are critical even for histologically well-differentiated, low-grade variants.