Carcinosarcoma ex recurrent pleomorphic adenoma of the submandibular gland

We report a case of carcinosarcoma ex recurrent pleomorphic adenoma in the submandibular region of a 56-year-old Japanese man. He presented with a 2-year history of a rapidly growing mass in the submandibular region. He reported undergoing excision of a nodule in the same region 10 years earlier. Incisional biopsy confirmed the diagnosis of pleomorphic adenoma. The lesion was excised surgically. The resected tumor measured 40 x 20 mm and was composed of two large nodules and multiple small satellite nodules in the subcutaneous tissue. Histopathologically, one large nodule was carcinosarcoma while the other large nodules and small satellite nodules were pleomorphic adenoma. The former large nodule showed a variegated pattern with carcinomatous components (poorly differentiated adenocarcinoma, salivary duct carcinoma, squamous cell carcinoma and undifferentiated carcinoma) and sarcomatous components (spindle cell sarcoma, chondrosarcoma, liposarcoma and rhabdomyosarcoma). Based on the clinical history and histopathology, we consider the lesion to have originated from recurrent pleomorphic adenoma.