Myeloid/Lymphoid neoplasms with abnormalities of PDGFRB

2017-04-01   Joanna Chaffin , Natasha M. Savage , Katrina L. Lancaster-Shorts 

1.Department of Pathology, Augusta University, Augusta, GA, USA; nsavage@augusta.edu

Abstract

This insert represents a review of myeloid and lymphoid neoplasms with abnormalities of PDGFRB including clinical presentation, morphologic review, and cytogenetic findings.

Clinics and Pathology

Disease

Myeloid and lymphoid neoplasms with abnormalities of PDGFRB are neoplasms in which eosinophilia is typical, although not required. Gene fusions with PDGFRB were first described by Golub et al. in 1994 in a patient with features consistent with chronic myelomonocytic leukemia (CMML). Since that time, over 20 fusion partners have been described. The entity was first formally accepted in the 2008 edition of the World Health Organizations Classification of Tumours of Haematopoietic and Lymphoid Tissues along with abnormalities of PDGFRA and FGFR1. In the WHO 2016 edition, myeloid and lymphoid neoplasms with eosinophilia and t(8;9)(p22;p24.1) PCM1 / JAK2 is now recognized as a provisional entity.

Phenotype stem cell origin

The cell of origin is a hematopoietic cell with commitment to eosinophilic differentiation.

Epidemiology

Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRB (as well as abnormalities of PDGFRA and FGFR1) are rare. Adult males are most commonly affected with a median age of onset in the late forties; however, older adults and rarely children have also been affected.

Clinics

Patients typically present with splenomegaly with hepatomegaly being less frequent; lymphadenopathy may also be seen. As with abnormalities of PDGFRA, skin and cardiac infiltration may be present at diagnosis with resulting cardiac damage.

Pathology

In patients with abnormalities of PDGFRB, peripheral blood and bone marrow are almost always involved with typical leukocytosis and possible concordant anemia and/or thrombocytopenia. Leukocytosis is usually predominated by monocytosis and eosinophilia imparting a chronic myelomonocytic leukemia (CMML)-like picture with eosinophilia (Figure 1 and 2). Eosinophils may have atypical morphology. Rarely, basophilia is also prominent. However, some patients present with features more suggestive of atypical chronic myeloid leukemia without BCR / ABL1 (aCML) or chronic eosinophilic leukemia (CEL) or more rarely, they present with phenotypic features of acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), or juvenile myelomonocytic leukemia (JMML).
The bone marrow is typically hypercellular (Figure 3) with accompanying fibrosis. As in cases with PDGFRA abnormalities, mast cell aggregates (not meeting criteria for systemic mastocytosis) can be seen.
Atlas Image
Monocytosis is seen along with atypical eosinophils with cytoplasmic vacuolation, uneven granule distribution, and increased nuclear lobes. (Wright Giemsa stained peripheral blood smear, original magnification 500x)
Atlas Image
Leukocytosis is noted with increased monocytes and several blasts. In addition, an atypical eosinophil is noted with sparse uneven granule distribution. (Wright Giemsa stained peripheral blood smear, original magnification 1000x)
Atlas Image
A markedly hypercellular bone marrow with myeloid hyperplasia including many eosinophils is appreciated. (Hematoxylin and Eosin stained bone marrow biopsy, original magnification 500x)

Treatment

Patients with abnormalities of PDGFRB are exquisitely sensitive to imatinib, like patients with abnormalities of PDGFRA, and this is the drug if choice. Primary and secondary resistance is uncommon; initial response typically occurs within 2 months.

Prognosis

Previously, this neoplasm was cited as an aggressive disease with a median overall survival of less than 2 years. However, after the universal initiation of imatinib as standard therapy, a recent study cited a 10-year overall survival of 90% (Cheah et al., 2014).

Cytogenetics

Atlas Image
G-banded karyotype demonstrating 46,XY,t(5;12)(q33.1;p13.2).

Genes Involved and Proteins

Gene name
PDGFRB (platelet-derived growth factor receptor, beta polypeptide)
Location
5q32
Note
Platelet Derived Growth Factor Receptor Beta (PDGFRB) is located on chromosome 5, band q32. It contains 23 exons and spans approximately 149.5 Mb. The encoded protein is 1067 amino acids. As with PDGFRA, it is a member of the type III class of tyrosine kinase receptors.

Bibliography

Pubmed IDLast YearTitleAuthors
125424822003Novel translocations that disrupt the platelet-derived growth factor receptor beta (PDGFRB) gene in BCR-ABL-negative chronic myeloproliferative disorders.Baxter EJ et al
246870852014Patients with myeloid malignancies bearing PDGFRB fusion genes achieve durable long-term remissions with imatinib.Cheah CY et al
81681371994Fusion of PDGF receptor beta to a novel ets-like gene, tel, in chronic myelomonocytic leukemia with t(5;12) chromosomal translocation.Golub TR et al
264863512015World Health Organization-defined eosinophilic disorders: 2015 update on diagnosis, risk stratification, and management.Gotlib J et al
234893242013Myeloid neoplasms associated with eosinophilia and rearrangement of PDGFRA, PDGFRB, and FGFR1: a review.Savage N et al

Citation

Joanna Chaffin ; Natasha M. Savage ; Katrina L. Lancaster-Shorts

Myeloid/Lymphoid neoplasms with abnormalities of PDGFRB

Atlas Genet Cytogenet Oncol Haematol. 2017-04-01

Online version: http://atlasgeneticsoncology.org/haematological/1745/myeloid-lymphoid-neoplasms-with-abnormalities-of-pdgfrb

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