Aggressive basal cell carcinoma in a non-facial location in a cat: Perineural and lymphatic invasion with metastasis.

Background: Basal cell carcinomas (BCCs) in cats are generally regarded as benign skin tumors with low metastatic potential. However, rare cases of aggressive behavior and metastasis, primarily in the context of facial lesions, have been reported. Case Description: A 12-year-old neutered male Scottish Fold cat presented with a chronic, non-healing ulcer on the left hock. The initial excision lacked a histopathological diagnosis, and the lesion recurred. Biopsy of the lesion confirmed basal cell carcinoma. Despite limb amputation with clear margins and no regional lymph node involvement, distant cutaneous nodules appeared 6 months later and were histologically confirmed as metastatic BCC with lymphatic and perineural invasion. Wide-margin resections and systemic chemotherapy with carboplatin were performed; however, further lesions developed, and the cat succumbed to progressive disease. Conclusion: This case highlights a rare and aggressive variant of feline BCC arising outside the head and neck region. The lesion demonstrated metastatic spread, perineural and lymphatic invasion, and a poor response to treatment. Early histopathological evaluation of chronic skin ulcers is essential, and recognition of aggressive subtypes may facilitate more effective clinical management.