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

Diffuse large B-cell lymphoma (DLBCL) with plasmablastic features associated with t(2;17)(p23;q23) and characteristic granular cytoplasmic anaplastic lymphoma kinase-1 (ALK1) protein expression is a rare lymphoma subtype. Nodal and extranodal involvement has been reported. Our case is a 32-year-old man with right cervical adenopathy. Lymph node biopsy showed large atypical cells with prominent plasmablastic differentiation, abundant amphophilic cytoplasm, and prominent central nucleoli. Paraffin immunohistochemistry showed finely granular cytoplasmic ALK1 expression, positive CD138, IgA, p63 (VS38), focal positive epithelial membrane antigen and CD4, and lambda light chain restriction whereas negative CD20 and CD30 staining. While reports show detection of the unique CLTC-ALK fusion by either reverse transcription-polymerase chain reaction or fluorescence in situ hybridization, our case represents the second case in the literature to detect the t(2;17)(p23;q23) translocation by multiplex karyotyping (multiplex fluorescence in situ hybridization) and the usefulness of this technique to detect hidden translocations not seen by G-banding. An add(2)(p23) was also seen not previously reported. Differential diagnoses of neoplasms with plasmablastic differentiation and a comprehensive molecular/cytogenetic literature review of ALK+DLBCL is discussed.