Histopathology and Cytology of Pulmonary Myoepithelial Neoplasms: 2 Cases

Myoepithelial neoplasms (MNs) of the lung are extremely rare tumors. Approximately 40 cases of pulmonary MNs have been reported to date. Herein, we report extremely rare cases of different types of pulmonary MN, including cytological features. Case 1 is an 18-year-old female, and case 2 is a 73-year-old female patient. They presented to our hospital with nodules of the lung. Histological examination revealed tumor cells with round to oval nuclei and acidophilic cytoplasm that formed nests or fascicles with mild hyalinized stroma in case 1 and tumors containing the bi-phasic components of a nest-like and fascicle pattern with pleomorphism in case 2. Immunohistochemically, these tumors were positive for cytokeratin (CK) AE1/AE3, CK5/6, vimentin, calponin, and EMA, and focal positive for S-100a protein and alpha smooth muscle actin. The pathological diagnoses in cases 1 and 2 were myoepithelioma and myoepithelial carcinoma, respectively. In conclusion, we encountered two cases of extremely rare MNs that occurred in the lung. This disease can be diagnosed by collecting appropriate cytological and histological findings and should be listed as a differential diagnosis.