Precursor B-cell lymphoblastic lymphoma - A study of nine cases lacking blood and bone marrow involvement and review of the literature

We describe 9 cases of precursor B-cell lymphoblastic lymphoma (LYL) withou t evidence of marrow or blood involvement. Four patients had superficial no dal disease. 2 cutaneous involvement, and I each ovarian, retroperitoneal, or tonsillar primary tumor: Sir patients had limited disease; 3 patients we re stage III. Immunophenotyping revealed a terminal deoxynucleotidyl transf erase (TdT)-positive, immature B-cell population with variable expression o f CD10, CD20, and CD45. All patients are in complete clinical remission (me dian follow-up, 14 months). A literature review yielded 105 patients with a diagnosis of precursor B-cell LYL bused on less than 25% marrow involvemen t. Of these, 64% were younger than 18 years. Skin, lymph nodes, and bone we re the most common sites of disease. Mediastinal involvement was uncommon. TdT; CD19, CD79a, CD10, and HLA-DR were the most frequently expressed antig ens, while CD45 and CD20 were expressed in only two thirds of the cases. Cy togenetic analysis showed additional 21q material as a recurring karyotypic abnormality At a median follow-up of 26 months, 74% of patients were alive : the median survival was 19 months for patients dying of disease. Comparis on with precursor B-cell acute lymphoblastic leukemia showed several overla pping features, although distinct differences were identified.