Spindle cell tumors of the pleura: Differential diagnosis
Thoracic Oncology Program, Cardinal Bernardin Cancer Center, Loyola University, Maywood, Illinois, USA. Seminars in Diagnostic Pathology
(Impact Factor: 2.56).
03/2006; 23(1):44-55. DOI: 10.1053/j.semdp.2006.06.002
Spindle cell tumors that arise in or metastasize to the pleura must be thoroughly evaluated to arrive at a definitive diagnosis. Malignant mesothelioma is the most common tumor arising in the pleura, but metastatic tumors to the pleura occur more frequently. Additionally, many tumors arising in the lung and surrounding tissues involve the pleura. It is crucial to arrive at a correct diagnosis since many of these neoplasms show different prognoses and require varying treatment modalities. Sarcomatoid malignant mesothelioma is a rare tumor that arises in the pleura, and can be confused with numerous tumors arising in or metastasizing to the pleura, including synovial sarcoma, metastatic sarcomatoid carcinoma, metastatic melanoma, thymoma, renal cell carcinoma, localized fibrous tumor, leiomyosarcoma, and other types of sarcoma. Desmoplastic malignant mesothelioma is a fibrous sarcomatoid variant of malignant mesothelioma, and is occasionally mistaken for chronic fibrous pleurisy. Here, we review morphological, clinical, histological, immunohistochemical, ultrastructural, and molecular methods that aid in the diagnosis of spindle cell tumors of the pleura, and we provide specific examples of patients in which this multi-modal approach proved to be helpful.
Available from: Brent D Kerger
- "Synovial sarcoma is a relatively rare malignancy that typically occurs in adolescents and young adults between the ages of 15 and 50 years of age and most commonly affects the extremities in the vicinity of large joints such as the knee or the thigh (Cadman et al., 1965; Cordon-Cardo, 1997; Nicholson et al., 1998; Cappello and Barnes, 2001; Kumar et al., 2005c) and the hands or feet (Michal et al., 2006). Because synovial sarcoma can be difficult to distinguish from reactive mesothelial proliferation and sarcomatoid mesothelioma by use of histology and immunohistochemical markers alone (Shiraki et al., 1989; Moran et al., 1992; Nicholson et al., 1998; Miettinen et al., 2001; Carbone et al., 2002; Gladish et al., 2002; Vohra et al., 2004; Taylor et al., 2005; Michal et al., 2006; Rdzanek et al., 2006), it represents another alternative carcinoma to consider when evaluating suspected sarcomatoid mesothelioma cases. This has been particularly true since the discovery of highly specific genetic lesions [t(x;18), SYT-SSX1, SSX2, and SSX4 fusion genes] in synovial sarcoma tumors that clinically distinguish this particular this tumor type (Colwell et al., 2002; Amary et al., 2007; Weinbreck et al., 2007). "
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ABSTRACT: The diagnosis of mesothelioma is not always straightforward, despite known immunohistochemical markers and other diagnostic techniques. One reason for the difficulty is that extrapleural tumors resembling mesothelioma may have several possible etiologies, especially in cases with no meaningful history of amphibole asbestos exposure. When the diagnosis of mesothelioma is based on histologic features alone, primary mesotheliomas may resemble various primary or metastatic cancers that have directly invaded the serosal membranes. Some of these metastatic malignancies, particularly carcinomas and sarcomas of the pleura, pericardium and peritoneum, may undergo desmoplastic reaction in the pleura, thereby mimicking mesothelioma, rather than the primary tumor. Encasement of the lung by direct spread or metastasis, termed pseudomesotheliomatous spread, occurs with several other primary cancer types, including certain late-stage tumors from genetic cancer syndromes exhibiting chromosomal instability. Although immunohistochemical staining patterns differentiate most carcinomas, lymphomas, and mestastatic sarcomas from mesotheliomas, specific genetic markers in tumor or somatic tissues have been recently identified that may also distinguish these tumor types from asbestos-related mesothelioma. A registry for genetic screening of mesothelioma cases would help lead to improvements in diagnostic criteria, prognostic accuracy and treatment efficacy, as well as improved estimates of primary mesothelioma incidence and of background rates of cancers unrelated to asbestos that might be otherwise mistaken for mesothelioma. This information would also help better define the dose-response relationships for mesothelioma and asbestos exposure, as well as other risk factors for mesothelioma and other mesenchymal or advanced metastatic tumors that may be indistinguishable by histology and staining characteristics.
Available from: Julia A Bridge
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ABSTRACT: Sarcomas constitute a heterogeneous group of rare tumors that in recent years have been shown by cytogenetic analysis to have a remarkably high incidence of specific and primary alterations. These genetic alterations not only have guided molecular studies in establishing the underlying genes involved, thereby yielding important pathogenetic information, but have also provided clinicians with a valuable tool to add to their diagnostic armamentarium. The addition of molecular cytogenetic (fluorescence in situ hybridization [FISH]) and molecular approaches (reverse transcriptase-polymerase chain reaction [RT-PCR]) has further enhanced the sensitivity and accuracy of detecting nonrandom chromosomal imbalances and/or structural rearrangements in sarcomas, including assessment in formalin-fixed, paraffin-embedded tissues. Poorly differentiated sarcomas represent a significant challenge to the pathologist as these neoplasms lack an identifiable hematoxylin and eosin-stained phenotype and often have lost diagnostic immunohistochemical or ultrastructural features as well. In contrast, primary cytogenetic changes and associated molecular events such as the 11;22 translocation in Ewing sarcoma are retained as a given tumor metastasizes or becomes less differentiated, as their presence appears to be vital for sustaining neoplastic transformation. Consequently, demonstration of characteristic, tumor-specific chromosomal aberrations is especially useful in the management of poorly differentiated sarcomas.
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ABSTRACT: The use of immunohistochemical stains has several applications in the evaluation of pulmonary and pleural neoplasms. The number of available immunohistochemical stains is continually expanding and, although these stains are an important diagnostic adjunct, their use is not without limitations and pitfalls.
To review and summarize the primary immunohistochemical applications with regard to the most common pulmonary and pleural neoplasms and discuss newly developed markers and common pitfalls.
Pertinent peer-reviewed literature emphasizing immunohistochemical applications in common lung and pleural tumors, unusual and problematic staining patterns in frequently encountered subtypes/histologic variants, and recently developed immunohistochemical stains of potential promise.
Immunohistochemical stains provide the greatest aid in establishing the site of origin of adenocarcinomas encountered in the lung and in separating epithelioid mesothelioma from adenocarcinoma. Certain subtypes of pulmonary adenocarcinomas may exhibit unusual staining patterns that may be potentially problematic. Immunohistochemistry has a more limited role in separating small cell carcinoma from non-small cell carcinoma, and extreme caution must be used in the situation of crushed biopsy specimens.
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