Primary pulmonary rhabdomyosarcoma can be divided into two groups - tumour in the normal lung, and tumor in cystic lesions of the lung.
These rare tumours of lung may present within normal lung parenchyma as solid mass or as endobronchial lesions with symptoms of pulmonary obstruction.
Histologically, both alveolar or embryonal variants are seen.
Cytoplasmic cross-striations and immunohistochemical stains are of great value for diagnosis.
Primary pulmonary rhabdomyosarcoma should be considered in the differential diagnosis of poorly differentiated pulmonary neoplasms in adults and should be distinguished from other primary and metastatic sarcomas.
According to one study "grossly, the tumors ranged in size from 6 to 11.5 cm and were tan-gray, firm masses with areas of necrosis and hemorrhage.
Histologically, the tumors were characterized by a spindle cell proliferation admixed with areas showing a pleomorphic cell population with numerous rhabdomyoblasts and areas of hemorrhage and necrosis.
Immunohistochemically, all three tumors showed strong positivity with desmin and myoglobin antibodies and negative staining with antibodies against cytokeratin, epithelial membrane antigen, and S-100 protein."
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