title: Bone marrow involvement in NPM-ALK-positive lymphoma: report of two cases.
abstract: Two cases of NPM-ALK-positive anaplastic large cell lymphoma (ALCL) with bone marrow involvement are reported. These cases were recognized within a group of NPM-ALK-positive ALCLs (n = 6) by using immunohistochemistry with the ALK1 monoclonal antibody. In case 1, the bone marrow showed diffuse infiltration of round to spindle-shaped lymphoma cells with moderate fibrosis. In case 2, lymphoma cells intermingling with hematopoietic cells could only be identified by immunohistochemical staining. In contrast to the four NPM-ALK-positive ALCL cases, which showed a cohesive growth pattern in the lymph nodes, the two cases reported here displayed lymphoma cells of smaller size, and they were classified as lymphohistiocytic variants histologically. ALK1 stained small-sized components more clearly than did CD30 (HRS-4). These results suggest that bone marrow involvement of NPM-ALK-positive ALCL may be frequently associated with a histological variant showing a small-sized cell component, and that ALK1 immunostaining is a useful tool to investigate lymphomas for bone marrow involvement.
authors.affiliation: Department of Pathology, Kawasaki Medical School, Kurashiki, Japan. sadapath@med.kawasaki-m.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Sadahira
authors.forename: S
authors.initials: S
authors.lastname: Hata
authors.forename: T
authors.initials: T
authors.lastname: Sugihara
authors.forename: T
authors.initials: T
authors.lastname: Manabe
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D000912:Antibodies, Neoplasm / Q000276:immunology; D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology; D017728:Lymphoma, Large-Cell, Anaplastic / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D015514:Oncogene Proteins, Fusion; C107023:p80(NPM-ALK) protein; D011505:Protein-Tyrosine Kinases