title: Primary bone marrow lymphoma:  an uncommon extranodal presentation of aggressive non-hodgkin lymphomas.
abstract: Bone marrow involvement by lymphoma is considered a systemic dissemination of the disease arising elsewhere, although some tumors may arise primarily in the bone marrow microenvironment. Primary bone marrow lymphoma (PBML) is a rare entity whose real boundaries and clinicobiological significance are not well defined. Criteria to diagnose PBML encompass isolated bone marrow infiltration, with no evidence of nodal or extranodal involvement, including the bone, and the exclusion of leukemia/lymphomas that are considered to primarily involve the bone marrow. Twenty-one out of 40 lymphomas retrospectively reviewed by the International Extranodal Lymphoma Study Group from 12 institutions in 7 different countries over a 25-year period fulfilled the inclusion criteria. These cases comprised 4 follicular lymphomas (FLs), 15 diffuse large B-cell lymphomas (DLBCLs), and 2 peripheral T-cell lymphomas, not otherwise specified. The FL cases showed paratrabecular infiltration, BCL2 protein and CD10 expression, and BCL2 gene rearrangement. DLBCL showed nodular infiltration in 6 cases and was diffuse in 9 cases; it also showed positivity for BCL2 protein (9/10) and IRF4 (6/8). Median age was 65 years with male predominance. All but 3 FL patients were symptomatic. Most cases presented with cytopenias and high lactate dehydrogenase. Four patients (3 FL cases and 1 DLBCL case) had leukemic involvement. Most DLBCL patients received CHOP-like or R-CHOP-like regimens. The outcome was unfavorable, with a median overall survival of 1.8 years. In conclusion, PBML is a very uncommon lymphoma with particular clinical features and heterogenous histology. Its recognition is important to establish accurate diagnosis and adequate therapy.
authors.affiliation: Hematopathology and Hematology Department, Hospital Clínic, IDIBAPS, University of Barcelona, Barcelona, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Martinez
authors.forename: Maurilio
authors.initials: M
authors.lastname: Ponzoni
authors.forename: Claudio
authors.initials: C
authors.lastname: Agostinelli
authors.forename: Konnie M
authors.initials: KM
authors.lastname: Hebeda
authors.forename: Estella
authors.initials: E
authors.lastname: Matutes
authors.forename: Jacopo
authors.initials: J
authors.lastname: Peccatori
authors.forename: Cristina
authors.initials: C
authors.lastname: Campidelli
authors.forename: Blanca
authors.initials: B
authors.lastname: Espinet
authors.forename: Granada
authors.initials: G
authors.lastname: Perea
authors.forename: Agustin
authors.initials: A
authors.lastname: Acevedo
authors.forename: Ali Zare
authors.initials: AZ
authors.lastname: Mehrjardi
authors.forename: Monica
authors.initials: M
authors.lastname: Martinez-Bernal
authors.forename: Marta
authors.initials: M
authors.lastname: Gelemur
authors.forename: Emanuele
authors.initials: E
authors.lastname: Zucca
authors.forename: Stefano
authors.initials: S
authors.lastname: Pileri
authors.forename: Elias
authors.initials: E
authors.lastname: Campo
authors.forename: Armando
authors.initials: A
authors.lastname: López-Guillermo
authors.forename: Maria
authors.initials: M
authors.lastname: Rozman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019046:Bone Marrow Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies