Malignant pilomatricoma in a dog with local and distant metastases treated with chemotherapy and bisphosphonates

A ten-year-old male neutered cross breed dog presented for evaluation of a mass associated with the left scapular bone, identified as a carcinoma. The dog had a malignant pilomatricoma removed from the left lateral thigh 6 months earlier. Histopathology review of the cutaneous and scapular mass identified the same tumour type, confirming metastatic disease; additional metastases to the inguinal lymph node, liver and lungs were identified. Chemotherapy resulted in partial responses/stable disease of very short duration. Bisphosphonates were administered due to lack of a measurable response and worsening of the associated lameness. The patient ultimately developed a symptomatic vertebral metastasis and was euthanased. The dog survived 255 days since medical treatment was started and 455 days since surgical removal of the primary tumour. This case report suggests that medical treatment with the addition of analgesia may be able to palliate clinical signs and possibly extend survival in dogs with metastatic epithelial cancer.