title: Indolent T-lymphoblastic proliferation (iT-LBP): a review of clinical and pathologic features and distinction from malignant T-lymphoblastic lymphoma.
abstract: In recent years, a new pathologic entity has emerged: indolent T-lymphoblastic proliferation (iT-LBP). iT-LBPs share immunophenotypic similarities with T-lymphoblastic lymphoma; however, T-lymphoblastic proliferations are clinically indolent, and unlike the malignant counterpart, these expansions of nonclonal terminal deoxynucleotidyl transferase (TdT)+ T cells do not require treatment. Here we review the clinical and pathologic features, which are required for an accurate diagnosis of an iT-LBP. We demonstrate specific criteria can be used to accurately diagnose iT-LBP, notably: (1) confluent groups of TdT+ T cells in a biopsy specimen, (2) relative preservation of surrounding normal lymphoid architecture, (3) TdT+ T cells without morphologic atypia, (4) absence of thymic epithelium, (5) nonclonal TdT+ T cells, (6) immunophenotype of developmentally normal immature thymic T cells, and (7) clinical evidence of indolence (follow-up >6 mo without progression).
authors.affiliation: Department of Pathology, Stanford University Medical Center, Stanford, CA 94305, USA. rohgami@stanford.edu
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ohgami
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Arber
authors.forename: James L
authors.initials: JL
authors.lastname: Zehnder
authors.forename: Yasodha
authors.initials: Y
authors.lastname: Natkunam
authors.forename: Roger A
authors.initials: RA
authors.lastname: Warnke
mesh_terms: D000328:Adult; D000368:Aged; D004273:DNA, Neoplasm / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006965:Hyperplasia; D016130:Immunophenotyping; D008198:Lymph Nodes / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D011230:Precancerous Conditions; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis* / Q000276:immunology / Q000628:therapy; D011379:Prognosis; D013601:T-Lymphocytes / Q000473:pathology*
chemical_list: D004273:DNA, Neoplasm