Childhood de novo CD5+ Diffuse Large B-cell Lymphoma: a Separate Entity?

Area of Science:

• Pediatric Oncology
• Hematology
• Cancer Biology

Background:

• De novo CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is a rare subtype typically affecting older adults.
• This lymphoma subtype is characterized by female predominance and aggressive clinical behavior.
• CD5+ DLBCL has not been previously described in the pediatric population.

Observation:

• A 12-year-old boy presented with ileocecal intussusception.
• Radiologic, morphologic, and immunophenotypic analyses revealed an isolated extranodal mass.
• The mass was consistent with CD5+ DLBCL with a germinal center cell phenotype.

Findings:

• Fluorescent in situ hybridization was negative for common oncogenic rearrangements (cMYC, BCL6, BCL2, MLL, IGH/CCND1).
• Loss of one copy of MLL was observed in 32% of cells.
• The patient achieved complete remission after four cycles of chemotherapy (cyclophosphamide, vincristine, prednisolone, methotrexate, and doxorubicin).

Implications:

• This case expands the known demographic spectrum of CD5+ DLBCL to include children.
• Highlights the importance of considering rare lymphoma subtypes in pediatric oncology.
• Suggests that pediatric CD5+ DLBCL may have a distinct biological profile and potentially respond to standard chemotherapy regimens.