In situ follicular lymphoma with a 14;18 translocation diagnosed by a multimodal approach.

The main differential diagnosis for follicular lymphoma (FL, or in situ localization of follicular lymphoma) is follicular hyperplasia. However, this differentiation is quite challenging when the initial presentation of FL is in one lymph node and such a lymph node is only partially involved. In other words, only a few lymphomatous follicles are present in an otherwise nodal reactive follicular hyperplasia. The use of FISH on formalin-fixed, paraffin-embedded tissue as an adjunct to routine histomorphological and immunohistochemical evaluation is valuable for reaching an initial diagnosis of in situ follicular lymphoma in a lymph node which shows predominantly reactive follicular hyperplasia. In this report, we describe our experience in rendering such an initial diagnosis of in situ FL in an apparently healthy individual who has a single persistently enlarged lymph node. The recognition of in situ FL is of utmost importance because it is associated with localized early stage disease (stage I), which according to standard regimens is amenable to local radiation therapy with a good chance for inducing remission. To the best of our knowledge, this is the first such case reported in the English literature using innovative FISH technology on formalin-fixed, paraffin-embedded tissue in conjunction with other routine histological modalities to produce an initial diagnosis of in situ follicular lymphoma.

Chronic idiopathic myelofibrosis (CIMF) resulting from a unique 3;9 translocation disrupting the janus kinase 2 (JAK2) gene.

We report a case of t(3;9)(q21;p24) in a patient with chronic idiopathic myelofibrosis (CIMF), a chronic myeloproliferative disorder (CMPD), initially detected by G-banding and fluorescent in situ hybridization (FISH) in an unstimulated culture of peripheral blood. Subsequent cytogenetic studies of bone marrow aspirates showed the presence and persistence of the same translocation. No additional cytogenetic abnormalities were found. This appears to be a unique translocation that has not been previously reported in the English literature, although both breakpoints, 3q21 and 9p24, are well known cancer-related breakpoints. The former is the mapped location of the ribophorin 1 (RPN1) gene, whereas the latter is the mapped location of the janus kinase 2 (JAK2) gene. This raises the possibility that disruption of one or both loci at the breakpoints of the presently described structural chromosomal rearrangement may be the primary event leading to the initiation and development of the hematopoietic disorder in this patient. It is not unreasonable to hypothesize that the juxtaposition of the RPN1 gene on 3q21 with the JAK2 gene on 9p24 leads to enhanced JAK2 activity. Additional studies will be needed to provide further support for or to disprove this hypothesis. To the best of our knowledge, this is the first reported case of CIMF associated with a reciprocal 3;9 translocation with the 3q21 and 9p24 breakpoints. The elucidation of the mechanism of leukemogenesis in CIMF may one day lead to successful targeted therapy in this hematopoietic disorder. It may also shed additional light on the diagnosis, prognosis and treatment of certain other cancers with similar genetic etiologies.