Mucoepidermoid carcinoma of the lung is a rare subtype of bronchial adenoma first described 35 years ago by Smetana et al. Although initially perceived to be a slow-growing neoplasm exhibiting local but not distant spread, dissemination was later described by Ozlu et al in 1961. Widespread metastases have since been described by many authors. Of μg previously reported cases with metastatic disease, most patients reported pulmonary symptoms, such as cough and hemoptysis, that antedated the diagnosis by several months to years. Physical examination, though infrequently described, revealed pulmonary abnormalities such as consolidation or wheezing, consistent with bronchial obstruction. The primary tumor was usually easily identified on the chest roentgenogram, and due to its frequent central location and airway origin, could be visualized and diagnosed by bronchoscopy in the majority of instances. Both lymphangitic and hematogenous routes of dissemination have been demonstrated. my canadian pharmacy online
The usual metastatic sites are the regional lymph nodes (48 percent), other portions of the lung (25 percent), bone marrow (25 percent), distant lymph nodes (18 percent), adrenal gland (14 percent), the brain parenchyma (14 percent) and skin (14 percent). There have been infrequent reports of renal, pleural,- pericardial, mediastinal, dura mater, and gastrointestinal (liver, spleen, intestines, esophagus and pancreas) involvement. Axelsson et al described metastatic spread of a primary lung mucoepidermoid carcinoma with low grade histologic characteristics, a finding which Barsky et al and Metcalf et al also demonstrated with light and electron microscopic techniques. However, most authors have observed that the histologic grade predicts clinical course.
The case of primary bronchial mucoepidermoid carcinoma we describe did display a concordant malignant histologic pattern, that is, the characteristic admixture of epidermoid and mucus-producing cells with brisk mitoses and metastatic foci, and clinical course. However, this case is unusual in several respects. The patient had no symptom or physical sign of a lung lesion. Findings consistent with a space-occupying central nervous system lesion were the only tumor manifestations. The chest roentgenogram and thoracic CT demonstrated lymphadenopathy without a parenchymal mass lesion. No endobronchial abnormality was found on fiberoptic bronchoscopic inspection. Cytologic specimens were negative for tumor cells, and gross pathologic examination confirmed very minor bronchial changes despite bulky regional and distant metastatic disease.
To summarize the data derived from this patient and from those cases of metastatic lung mucoepidermoid carcinoma reviewed here, the following statements can be made: due to the involvement of central airways and the frequent obstruction of a bronchus by the primary lesion, pulmonary symptoms and an abnormal chest examination are usually present. Chest roentgenograms are generally abnormal, though a distinct parenchymal mass may be absent. Visualization and diagnosis by means of bronchoscopy are possible in the majority of instances. The tumors biologic behavior may not parallel the histologic grade. Both lymphangitic and hematogenous spread can occur, with regional and distant lymph nodes, other portions of the lung and bone marrow the most frequent sites of involvement. Finally, brain metas-tases, although infrequent, may be the initial and only manifestation of the tumor.