title: Frequent expression of CD99 in anaplastic large cell lymphoma: a clinicopathologic and immunohistochemical study of 160 cases.
abstract: Originally described as a diagnostically useful marker for Ewing sarcoma, CD99 immunoreactivity has also been documented in a variety of other tumors, including hematopoietic neoplasms. By using conventional paraffin immunoperoxidase staining and tissue microarrays, we retrospectively investigated CD99 expression in a series of 160 anaplastic large cell lymphoma (ALCL) cases. Of the 160 cases, 103 (64.4%) were positive for CD99. The distribution of CD99 positivity was similar for nodal (66/103 [64.1%]), extranodal, (21/32 [66%]), and primary cutaneous lesions (16/25 [64%]). CD99 expression was present in 96 (64.4%) of 149 of the common type, 4 (80%) of 5 of the small cell variant, and 3 (50%) of 6 of the lymphohistiocytic variant cases. CD99 expression was slightly more frequent in anaplastic large cell lymphoma kinase (ALK)+ cases compared with ALK- cases (43/54 [80%] vs 44/81 [54%]). With 2 exceptions, ALK+ ALCL was seen only in patients younger than 41 years. We conclude that CD99 is frequently expressed in ALCL, with a slightly increased frequency in the younger age ALK+ cases. Nodal and extranodal ALCL should be considered in the differential diagnosis when a CD99+ neoplasm is encountered.
authors.affiliation: Department of Pathology and Laboratory Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Buxton
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Bacchi
authors.forename: Gabriela
authors.initials: G
authors.lastname: Gualco
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Weiss
authors.forename: Craig W
authors.initials: CW
authors.lastname: Zuppan
authors.forename: Edward H
authors.initials: EH
authors.lastname: Rowsell
authors.forename: Qin
authors.initials: Q
authors.lastname: Huang
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
mesh_terms: D000071443:12E7 Antigen; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077548:Anaplastic Lymphoma Kinase; D015703:Antigens, CD / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D017728:Lymphoma, Large-Cell, Anaplastic / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases; D046888:Tissue Array Analysis
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases