ALK-positive diffuse large B-cell lymphoma with the t(2;17)(p23;q23)

Area of Science:

• Hematology
• Oncology
• Cytogenetics

Background:

• Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group of aggressive non-Hodgkin lymphomas.
• A rare subtype of DLBCL exhibits plasmablastic differentiation and anaplastic lymphoma kinase-1 (ALK1) expression.
• This subtype is characterized by the t(2;17)(p23;q23) translocation, leading to a unique CLTC-ALK fusion gene.

Observation:

• A case of a 32-year-old male presenting with right cervical adenopathy.
• Lymph node biopsy revealed large atypical cells with plasmablastic features, abundant cytoplasm, and prominent nucleoli.
• Immunohistochemistry showed granular cytoplasmic ALK1 expression, CD138, IgA, p63, and lambda light chain restriction, with negativity for CD20 and CD30.

Findings:

• The t(2;17)(p23;q23) translocation was identified using multiplex karyotyping, a technique effective for detecting cryptic translocations.
• This represents the second reported case utilizing multiplex karyotyping for this specific translocation.
• An additional chromosomal abnormality, add(2)(p23), not previously described in this context, was also observed.

Implications:

• Multiplex karyotyping is a valuable tool for diagnosing rare ALK-positive DLBCL subtypes by detecting complex or hidden translocations.
• Accurate molecular and cytogenetic characterization is crucial for understanding the pathogenesis and classification of DLBCL subtypes.
• This case contributes to the literature on ALK-positive DLBCL, highlighting diagnostic challenges and the utility of advanced cytogenetic techniques.