Myoepithelial carcinoma of submaxillary gland: A case report.

Myoepithelial carcinoma (MEC) is a malignant tumour composed almost entirely of cells differentiated from the myoepithelium. It is rare, most commonly occurring in the parotid gland. In the current study, a rare case of MEC in the submandibular gland was presented. An 82-year-old male patient was admitted with a swelling in the upper left neck that had been present for 60 years. Magnetic resonance imaging indicated a tumour in the region of the left submandibular gland, which was not easy to clearly distinguish from the gland itself and an enhancement scan was recommended but not performed. Furthermore, multiple lymph nodes of varying sizes were present in the submandibular region of the neck on both sides. These enlarged lymph nodes had signs of involvement. Accordingly, a surgery was performed. The pathological diagnosis indicated the presence of a malignant tumour in the left upper neck. The tumour was most likely an MEC with pleomorphic adenoma, based on the results of immunohistochemistry. The size of the tumour mass was 5×5×4 cm. Histology indicated that the tumour cells exhibited infiltrative growth, with a sparse arrangement and a predominance of hyaline and spindle-shaped cells. In certain regions, the tumour tissue displayed characteristics similar to pleomorphic adenoma. The results of the immunohistochemical analysis were as follows: CD31(-), CD34(-), cytokeratin (CK)7 (+), vimentin (+), Ki-67 (+, 70%), erythroid growth factor receptor (-), desmin (-), anaplastic lymphoma kinase (-), P40 (+), CK pan-antibody (+) and epithelial membrane antigen (-). The patient underwent a surgical procedure to remove the lesion in the neck under sedation with complex anaesthesia. The sample excised from the surgery was sent to the pathology department for diagnosis. Given the high recurrence frequency of MEC, monitoring patients closely after surgery is crucial.