title: Desmoglein 3 and p40 immunoreactivity in neoplastic and nonneoplastic thymus: a potential adjunct to help resolve selected diagnostic and staging problems.
abstract: The potential usefulness of the squamous markers p40 and desmoglein 3 (DSG-3) for the diagnosis and staging of selected thymic lesions is uncertain. We investigated their expression and distribution pattern in 66 thymomas, 12 thymic squamous carcinomas, 6 undifferentiated thymic carcinomas, 5 hyperplastic thymi, and 5 normal thymi. p40 nuclear and DSG-3 cytoplasmic/membranous immunoreactivity in greater than or equal to 10% of thymic epithelial cells was interpreted as positive, and DSG-3 distribution pattern was classified as organotypic and nonorganotypic. All nonneoplastic thymic tissues, 100% of thymic squamous carcinomas, 97% of thymomas, and 50% of undifferentiated thymic carcinomas were positive for p40. Expression of p40 in almost all thymomas and in 50% of undifferentiated carcinomas that lacked squamous features suggests that p40 is not a good marker for the diagnosis of thymic squamous carcinoma. All normal and hyperplastic thymi, 51.5% of thymomas, and 0% of thymic squamous carcinomas expressed DSG-3 in an organotypic pattern, and 13.6% of thymomas and 83% of thymic squamous carcinomas were DSG-3 positive in a nonorganotypic pattern. Findings suggest that nonorganotypic DSG-3 expression favors the diagnosis of squamous cell carcinoma over thymoma. In 26 (60.5%) of the 43 cases where neoplastic and nonneoplastic thymus were present on the same slide, the presence/absence or distribution pattern of DSG-3 immunoreactivity was different in the 2 components, suggesting that this marker can be helpful in staging thymomas with incomplete encapsulation. The presence of DSG-3-positive and DSG-3-negative thymomas raises the possibility that these tumors may originate from 2 different types of thymic epithelial cells.
authors.affiliation: Department of Pathology & Laboratory Medicine, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles CA 90048. Electronic address: walts@cshs.org.
authors.forename: Ann E
authors.initials: AE
authors.lastname: Walts
authors.affiliation: Department of Pathology, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo, Japan. Electronic address: hiroshima.kenzo@twmu.ac.jp.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hiroshima
authors.affiliation: Department of Pathology & Laboratory Medicine, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles CA 90048. Electronic address: alberto.marchevsky@cshs.org.
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Marchevsky
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D051184:Desmoglein 3 / Q000032:analysis / Q000378:metabolism*; D005260:Female; D006801:Humans; D016056:Immunodominant Epitopes / Q000032:analysis / Q000378:metabolism*; D007124:Immunoenzyme Techniques / Q000379:methods; D008206:Lymphatic Diseases / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010446:Peptide Fragments / Q000032:analysis / Q000378:metabolism*; D013945:Thymoma / Q000378:metabolism* / Q000473:pathology; D013953:Thymus Neoplasms / Q000378:metabolism* / Q000473:pathology; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; C071894:DSG3 protein, human; D051184:Desmoglein 3; D016056:Immunodominant Epitopes; C495942:P40, iodinated C-terminal peptide, human; D010446:Peptide Fragments
keywords: Desmoglein 3; Squamous carcinoma; Thymic carcinoma; Thymoma; p40