Ki-1 lymphoma

Pediatric Anaplastic Large Cell (CD30+) Lymphomas Associated With the t(2;5) (p23;q35) Chromosomal Abnormality

Translocation of genetic material from the short arm of chromosome 2 to the long arm of chromosome 5, t(2;5)(p23;q35), has been associated with so-called histiocytic malignancies, with large T-cell lymphoma in childhood and with CD30+ (Ki-1) lym phoma. In an attempt to clarify the relationship between the t(2;5)(p23;q35) abnor mality and tumors in the pediatric age group, three cases of t(2;5)(p23;q35) from the files of the Adelaide Children's Hospital were accessed and clinical and histological data were reviewed. All cases had been originally diagnosed as hematolymphoid tumors. Histologically, the tumors were anaplastic large cell lymphomas, two of pleomorphic and one of monomorphic subtype. When immunohistochemistry was performed, all three were positive for CD30, characteristic of Ki-1 lymphoma. Two were positive for epithelial membrane antigen, all were positive for at least one T-cell marker, and all were negative for histiocytic markers. The monomorphic tumor recurred on several occasions, but the worst outcome occurred in one of the pleomorphic tumors, which proved fatal within 6 months. The precise significance of the breakpoints at 2p23 and 5q35 is not known, although it is not thought to be related to the proximity of the c-fms proto-oncogene, the colony stimulating factor 1 gene, or the N- myc proto-onco gene. The uniformity of the chromosomal abnormality contrasts with the variability of tumor morphology and clinical outcome. Close follow-up evaluation of current cases will be necessary to enable further characterization of this heterogeneous group of lymphoid tumors. Int J Surg Pathol 1 (1): 43-50, 1993