Myelodysplastic syndrome with isolated del(5q)

Author:  Mir Alikhan, MD, 08/25/2021
Category: Myeloid Neoplasms and acute leukemia (WHO 2016) > Myelodysplastic Syndromes (MDS) > Myelodysplastic syndrome with isolated del(5q)
Published Date: 09/10/2021

The patient is an 88-year-old woman who presents with fatigue and dizziness. She was found to have unexplained macrocytic anemia with a hemoglobin of 9.3 g/dL and MCV of 105.1. Platelet and absolute neutrophil counts were normal (308,000 k/uL and 2,200 k/uL, respectively).

A bone marrow biopsy showed trilineage but atypical hematopoiesis. Most notably, megakaryocytes were often small and hypolobated with many showing a plasmacytoid appearance. Erythroid precursors sometimes showed irregular nuclear contours. Blasts were not increased. An iron stain did not demonstrate ring sideroblasts.

Karyotype and FISH studies showed deletion of 5q in 12 of 20 cells, without other abnormalities. Next-generation sequencing studies were negative for significant alterations. A diagnosis of myelodysplastic syndrome with isolated del(5q) was rendered. The patient has been well without treatment since diagnosis (8 months prior), but has been transfusion dependent. Treatment with lenalidomide is being considered.

 

Learning Points:

- Myelodysplastic syndrome with isolated del(5q) is a distinct entity characterized by anemia without other cytopenias. It may also present with thrombocytosis

- It is more common in women of middle or elderly age

- Cytogenetic studies show del(5q) as the only abnormality. In some cases, there may be one additional abnormality, with the exception of monosomy 7 or del(7q)

- Megakaryocytic dysplasia is very characteristic, with small size and hypolobated, often eccentric nuclei. Dysplasia in other lineages are not as pronounced.

- Patients with MDS with isolated del(5q) generally show favorable prognosis. However, the evolution with additional chromosomal abnormalities or TP53 mutations can lead to poor outcomes.

- Treatment with lenolidomide can provide sustained remissions and transfusion independence in many cases.

Peripheral blood

Peripheral blood demonstrating macrocytosis without thrombocytopenia. Atypical, large platelets can be appreciated (arrow).

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Bone marrow aspirate smear

The marrow aspirate smear is cellular with trilineage hematopoiesis.

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Atypical megakaryocytes

Many atypical megakaryocytes are seen characterized by small size, hypolobated or non-lobated nuclei, and often plasmacytoid appearance with eccentric nuclei. Erythropoiesis and granulopoiesis are relatively unremarkable. Blasts are not increased.

Atypical-megakaryocytes
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Bone core biopsy

Core biopsy also demonstrates atypical, hypolobated megakaryocytes (arrow).

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Cytogenetic studies

Conventional karyotype analysis demonstrates deletion of the long arm of chromosome 5 (arrow).

Karyotype-Studies
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