Non-Hodgkin's Lymphoma (NHL) results from the malignant proliferation of cells of lymphocytic lineage. Although malignant lymphomas are generally restricted to lymphoid tissue such as lymph nodes and spleen, it is not uncommon to find bone marrow involvement in children.
INCIDENCE AND EPIDEMIOLOGYIncidence
- NHL accounts for 5-7% of malignant diseases in childhood (Europe, United States). It is the third most common childhood malignancy
- The incidence of NHL is higher in the Middle East, Nigeria, and Uganda (15 of 100,000 children under 5-10 years of age).
- NHL accounts for 60% of all childhood lymphomas
- Isolated cases of familial NHL have been known to occur.
Sex: M:F= 2.5:1
Age: Peak age 5-15 years
Genetic: Immunological defects (Bruton's type of sex-linked agammaglobulinemia, common variable agammaglobulinemia, ataxia telangiectasia, Wiskott-Aldrich syndrome, severe combined immune deficiency)
Post-transplant immunosuppression: Post-bone marrow transplantation (especially with use of T-cell depleted marrow); post-liver or post-heart transplantation.
Radiation: Children treated with chemo-radiotherapy for Hodgkin's disease
Virus: Epstein-Barr virus (EBV), human immune deficiency virus (HIV)
PATHOLOGIC CLASSIFICATIONTable 1 presents the Revised European - American Lymphoma (REAL) classification from the International Lymphoma Study Group. This classification for NHL is based on the currently recognized histologic (morphologic), immunologic, and genetic features; their clinical presentation, and course. Currently, the REAL classification is the preferred classification for NHL.
Table 1 : Revised European-American Lymphoma Classification from the International Lymphoma Study Group
Precursor B-cell neoplasms
Precursor B-lymphoblastic leukemia / lymphoma
Peripheral B-cell neoplasms
- B-cell CLL / PLL / SLL
- Lymphoplasmacytoid lymphoma / immunocytoma
- Mantle cell lymphoma
Follicle center lymphoma, follicular
- Provisional cytologic grades: I (small), II (mixed), III (large)
- Provisional subtype: diffuse, predominantly small cell
Marginal zone B-cell lymphoma
- Extranodal (MALT ± monocytoid B cells)
- Provisional category: nodal (± monocytoid B cells)
- Provisional entity : splenic marginal zone lymphoma
Hairy cell leukemia
Plasmacytoma / myeloma
Diffuse large B-cell lymphoma
- Provisional entity: high-grade B-cell lymphoma, Burkitt-type
T-cell and putative natural killer (NK) cell neoplasms
Precursor T-cell neoplasms
Precursor T-lymphoblastic lymphoma / leukemia
Peripheral T-cell and NK cell neoplasms
- T-cell CLL / PLL
- Large granular lymphocyte leukemia
- Mycosis fungoides / Sezary syndrome
- Peripheral T-cell lymphomas, unspecified
Provisional categories: medium, mixed, large, lymphoepitheloid
- Hepatosplenic T-cell lymphoma
Subcutaneous panniculitic T-cell lymphoma
- Adult T-cell lymphoma / leukemia
- Angioimmunoblastic T-cell lymphoma
- Angiocentric lymphoma
- Intestinal T-cell lymphoma (± enteropathy)
- Anaplastic large cell lymphoma (T/null)
- Provisional ALCL Hodgkin's-like
Note: CLL, chronic lymphocytic leukemia; PLL prolymphocytic leukemia; SLL, small lymphocytic lymphoma, MALT,mucosal associated lymphoid tissue lymphoma; ALCL, anaplastic large cell lymphoma
From Harris NL, Jaffe ES, Stein H, Banks PM,Chan JKS, Cleary ML, Delsol G et al. A revised European-American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group, Blood 1994, 84: 1361-92.
Fifty percent of NHL in children are small noncleaved, 30% lymphoblastic, and 20% large cell types.