VIEWS: 74 PAGES: 7 CATEGORY: Medicine POSTED ON: 7/14/2010
CONTEXT: Sarcomatoid carcinoma of the lung is a subset of poorly differentiated non-small cell lung cancers that are diagnostically challenging because they are uncommon, may reveal little of their parent cell of origin, and overlap morphologically with other anaplastic epithelioid and spindle cell tumors that can be primary in, or metastatic to, the lung and pleura. OBJECTIVE: To review the current histologic classification and diagnostic criteria that identify the 5 subtypes of sarcomatoid carcinoma of the lung and to discuss the most common tumors in the differential diagnosis. DESIGN: Published classification systems from the World Health Organization and pertinent peer-reviewed articles indexed in PubMed (National Library of Medicine) form the basis of this review. CONCLUSIONS: Identification of sarcomatoid carcinoma of the lung requires knowledge of specific histologic criteria that define the 5 subgroups, targeted immunohistochemical studies, and correlation with chest imaging to assess distribution of disease and to avoid misdiagnosis.
Sarcomatoid Carcinoma of the Lung Histologic Criteria and Common Lesions in the Differential Diagnosis Teri J. Franks, MD; Jeffrey R. Galvin, MD ● Context.—Sarcomatoid carcinoma of the lung is a subset Design.—Published classiﬁcation systems from the of poorly differentiated non–small cell lung cancers that World Health Organization and pertinent peer-reviewed are diagnostically challenging because they are uncom- articles indexed in PubMed (National Library of Medicine) mon, may reveal little of their parent cell of origin, and form the basis of this review. overlap morphologically with other anaplastic epithelioid Conclusions.—Identiﬁcation of sarcomatoid carcino- and spindle cell tumors that can be primary in, or meta- ma of the lung requires knowledge of speciﬁc histologic static to, the lung and pleura. criteria that deﬁne the 5 subgroups, targeted immuno- Objective.—To review the current histologic classiﬁca- histochemical studies, and correlation with chest imag- tion and diagnostic criteria that identify the 5 subtypes of ing to assess distribution of disease and to avoid misdi- sarcomatoid carcinoma of the lung and to discuss the most agnosis. common tumors in the differential diagnosis. (Arch Pathol Lab Med. 2010;134:49–54) P oorly differentiated non–small cell carcinomas of the lung with sarcoma-like differentiation (spindle and/ or giant cell) or a component of sarcoma (malignant bone, ond, regarding the histogenetic mechanisms that would al- low conventional subtypes of lung cancer to coexist with malignant spindle and/or giant cell elements and sarcoma. cartilage, or skeletal muscle) are uniﬁed within the um- For the past 25 years, the World Health Organization brella term sarcomatoid carcinoma by the World Health Or- has been under constant pressure to change the classiﬁ- ganization. Five subtypes are recognized: pleomorphic cation of sarcomatoid tumors of the lung. This has been carcinoma, spindle cell carcinoma, giant cell carcinoma, driven in part by the histologic heterogeneity of the tu- carcinosarcoma, and pulmonary blastoma.1 Sarcomatoid mors and in part by our evolving understanding of their carcinomas are rare, comprising approximately 1% of all histogenetic origins. The 1981 World Health Organiza- lung malignancies.2,3 Patients are predominantly male tion’s Histological Typing of Lung Tumours 12 recognized smokers, with a mean age at diagnosis of 65 years; cough spindle cell carcinoma as a variant of squamous cell car- and hemoptysis are the most common presenting symp- cinoma; giant cell carcinoma as a variant of large cell car- toms, the clinical course is aggressive, and as with con- cinoma; and carcinosarcoma and pulmonary blastoma as ventional non–small cell lung carcinoma, stage is the most miscellaneous malignant tumors. Classiﬁcations organiz- important prognostic indicator.2,4–11 Pulmonary blastoma is ing these lesions as monophasic or biphasic, with biphasic an exception in that it demonstrates an equal sex ratio and examples further subclassiﬁed as homologous or heterol- has a mean age at diagnosis of 35 years.6 ogous, were subsequently proposed and
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