Mediastinal masses are categorized as either anterior, middle, or posterior based on their location on the lateral chest roentgenogram. Mediastinal tumors show wide variability in histological classification and the frequencies of certain neoplasms differ in adults and children. Sarcomatoid Carcinoma (SCA) is a rare malignant tumor having a mixture of carcinoma and sarcoma containing differentiated mesenchymal elements. It may occur in such diverse locations as the uterus, breast, thyroid, lung, and upper gastrointestinal system. However, up to date a primary mediastinal SCA was only reported once in the literature(1).
A 44 year old African American man with a history of motor vihecle accident 3 years before “had a jaw fracture”, chronic smoking, and alcohol abuse, was admitted with a complain of pain between the scapulae bones, low grade fever, and 7 kg weight loss (all symptoms were for the last 3 months), the chest x-ray (postero-anterior and lateral) showed left side huge posterior mediastinal mass, chest CT showed a large lobulated mass measures 16 x 9 x 10 cm, occupies the posteromedial aspect of the left hemithorax in the paraspinal region extending form the level of the right hemidiaphragm to the clavicular head. A transthoracic core biopsy was done and biopsy showed highly pleomorphic malignant cells, containing spindle cells and huge multi-nucleated cells, mitosis were numerous, immunohistochemical staining was obtained and showed positivity for both carcinoma [Cytokeratin (CK) (CAM 5.2, and AE-1/3)] and Sarcoma [(SMA, Actin, and Vimentin)], and stain negative for Epithelial membrane antigen (EMA), CK 20, and CK-7 (which are markers for Carcinomas), and also negative for Desmin (which is marker for sarcoma). Head CT showed multiple brain lesions suggestive of brain metastasis. The patient was treated with chemotherapy and radiation of the brain lesions.
Mediastinal tumors show wide variability in histological classification and the frequencies of certain neoplasms differ in adults and children. Mediastinal tumors have high probability of being malignant and 25–49% malignancy rates are reported(2). Due to this high malignancy rate, diagnostic steps must not be full of details and therapy must be started as soon as possible. The diagnostic approach in these patients mostly includes diagnostic mediastinoscopy with biopsy and thoracotomy, the former being more frequent(3). SCAs of are uncommon neoplasms to which several other historical designations have been given. These include “spindle cell carcinoma,” “carcinosarcoma,” “pleomorphic carcinoma,” and “carcinoma with pseudosarcomatous stroma.” Current concepts regarding this lesion suggest that it is a clonal proliferation which is basically epithelial in nature, but with the potential to undergo divergent differentiation and assume various mesenchymal phenotypes.
In general carcinosarcoma being a mixed tumor can be localized in a wide variety of areas in the body and can originate from various organs including the lungs, organs of the gastrointestinal and the genitourinary systems. However, up to date a primary mediastinal carcinosarcoma has been reported once only in the literature. For all mediastinal tumors with a sarcomatoid pattern, especially a malignant fibrous histiocytoma pattern, extensive samples should be obtained and immunoperoxidase or ultrastructural studies done to identify epithelial differentiation.
M. Alakhras, None.