title: Flow cytometry in the diagnosis of mediastinal tumors with emphasis on differentiating thymocytes from precursor T-lymphoblastic lymphoma/leukemia.
abstract: Flow cytometry (FC) has become the routine technique in the evaluation of hematopoietic neoplasms. Since the anterior mediastinum is a frequent site of involvement by both primary and secondary lymphoma/leukemia, flow cytometry plays an important role in the evaluation of mediastinal masses. The present study reviews 100 flow cytometry cases from patients presenting with mediastinal lesions. In 5 cases (5%) flow cytometry was not diagnostic due to either insufficient cell yield or low viability. In the remaining cases (95/100) cell suspensions were adequate for flow cytometry evaluation. Results showed that in 31/32 (96.8%), 2/3 (66.7%), 7/9 (77.8%), 7/8 (87.5%) and 11/11 (100%) cases of B-cell lymphoma, T-cell lymphoma, carcinoma, T-ALL/LBL and thymoma/thymic hyperplasia, respectively, the diagnosis could be reached by flow cytometry alone. Excluding HL, the general sensitivity of FC in diagnosing mediastinal tumors was approximately 92%. Among the 100 cases, flow cytometry gave non-informative results in 3 cases of diffuse large B-cell lymphoma, 1 case of peripheral T-cell lymphoma, and 3 cases of carcinoma. No false positive results were encountered. The phenotypic pattern, especially surface CD3 expression versus forward scatter, reliably discriminated between immature thymocytes from thymoma/thymic hyperplasia from T-ALL/LBL. Flow methodology has the advantage of rapid turn-around time as well as high sensitivity, enabling patients with large anterior mediastinal masses and/or superior vena cava syndrome to begin treatment as promptly as possible. In experienced hands, flow cytometry plays a valuable and complementary role to histology and immunohistochemistry in diagnosing mediastinal tumors.
authors.affiliation: Division of Hematopathology, IMPATH Inc., 521 West 57th Street, New York, NY 10019, USA. wojciech.gorczyca@IMPATH.com
authors.forename: Wojciech
authors.initials: W
authors.lastname: Gorczyca
authors.forename: Sorina
authors.initials: S
authors.lastname: Tugulea
authors.forename: Zach
authors.initials: Z
authors.lastname: Liu
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Li
authors.forename: John Y L
authors.initials: JY
authors.lastname: Wong
authors.forename: James
authors.initials: J
authors.lastname: Weisberger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002454:Cell Differentiation; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D016130:Immunophenotyping; D007945:Leukemia, Lymphoid / Q000175:diagnosis / Q000473:pathology*; D008198:Lymph Nodes / Q000473:pathology; D008297:Male; D008479:Mediastinal Neoplasms / Q000175:diagnosis / Q000473:pathology*; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D013950:Thymus Gland / Q000473:pathology*