Primary leiomyosarcomas of the lung are a rare malignancy occurring in adults and represents less than 0.5% of all primary malignancy disease of the lung and 30% of primary sarcomas of the lung.[1
] A few cases of endobronchial localization have been described. Since 1967, only 14 cases in patients older than 20 years have been reported.[4
] In general, it occurs during middle age with a slight predominance of males. Due to the location of the endobronchial lesion, patients may present with symptom of pulmonary obstruction such as chest pain, cough, fever, wheezing, hemoptysis, dyspnea, and even expectoration of tumor fragments.[5
] The radiological appearances include the findings of bronchial obstruction such as atelectasis, mediastinal shift and hyperlucency, or pneumothorax.[5
A definitive preoperative diagnosis of endobronchial leiomyosarcoma is extremely difficult. In the literature reviewed, only five of the 14 (37%) cases had a definite preoperative diagnosis.[4
] The morphologic features of these tumors recapitulate those seen in soft tissue, namely a fascicular proliferation of spindle cells with moderate amounts of eosinophilic cytoplasm, cigar-shaped nuclei, and inconspicuous nucleoli.[6
] Pulmonary leiomyosarcoma can show a wide spectrum of differentiation. Low-grade tumors are characterized by a well-developed fascicular arrangement of tumor cells intersecting at right angles, with low mitotic rates (<3per 10 hpf) and absence of cellular atypia, necrosis and hemorrhage. Intermediate-grade tumors are characterized by increased cellularity with mild to moderate nuclear atypia and brisk mitotic activity (3-8 mitoses per 10 hpf). High-grade tumors show marked cellularity with nuclear pleomorphism and atypia, high mitotic activity (average 8-12 mitoses per 10 hpf), abundant necrosis, and hemorrhage.[6
] In immunohistochemical studies, low-grade (well diff erentiated) tumors are more likely to show immunoreactivity for muscle markers, such as smooth muscleactin, h-caldesmone and desmin, while the less differentiated (high-grade tumors) can be negative for all muscle markers and require ultrastructural examination to confirm the diagnosis. It is important to note that some smooth muscle tumors may show a positive reaction for cytokeratin.
A panel of epithelial markers is therefore recommended when evaluating spindle-cell neoplasm of the lung to avoid misinterpretation as carcinosarcoma that contain a component of sarcomatoid differentiation.
Surgical resection of the tumor was a favorite modality of treatment for these tumors. However, to complete resection and prolong survival, sleeve lobectomy, pneumonectomy or carcinal resection may be necessary, depending on the anatomic location and size of the tumor.[7
] Chemotherapy is suggested in case with metastases, but is very inefficient with a partial response and short duration. The protocols using adriamycin have shown a response rate of 16-27 %.[7
The prognosis appears to correlate directly with tumor grade and degree of differentiation. The low-grade tumors generally follow a less aggressive course than those of intermediate or high–grade.[5
] Other prognostic factors as the size and long-time stability of solitary lung nodules are not necessarily reliable criteria for assessing prognosis.[8
In summary, primary endobronchial leiomyosarcoma is a very rare clinical and pathological entity. The surgical resection should be the favored method for definitive diagnosis and curative treatment.