Polycythemia Vera: New Clinicopathologic Perspectives

JAK 2 positive myeloproliferative neoplasm presenting as stroke, recurrent TIA and isolated third nerve palsy

A man in his early 40s with no significant vascular risk factors was managed within a period of 6 months for recurrent vascular events: ischaemic stroke, transient ischaemic attack and isolated third nerve palsy. He was extensively investigated throughout the course of illness. The only potential aetiological factor identified was a positive janus kinase 2 (JAK 2) mutation after screening on account of mildly elevated platelet count noted during his most recent admission. Bone marrow aspiration confirmed essential thrombocythaemia. He was started on hydroxycarbamide and has remained relatively symptom free since then.This case reiterates the known associations between thrombosis and JAK 2 mutation even without overt myeloproliferative neoplasms. It also highlights the need for specialists in stroke to consider screening for JAK 2 mutation in a young patient with cryptogenic stroke with or without polycythemia or thrombocytosis.

Movement disorders in systemic diseases

Movement disorders, classically involving dysfunction of the basal ganglia commonly occur in neurodegenerative and structural brain disorders. At times, however, movement disorders can be the initial manifestation of a systemic disease. In this article we discuss the most common movement disorders which may present in infectious, autoimmune, paraneoplastic, metabolic and endocrine diseases. Management often has to be multidisciplinary involving primary care physicians, neurologists, allied health professionals including nurses, occupational therapists and less frequently neurosurgeons. Recognizing and treating the underlying systemic disease is important in order to improve the neurological symptoms.

Polycythemia vera presenting as acute myocardial infarction: An unusual presentation

Acute myocardial infarction (AMI) is usually seen in the setting of atherosclerosis and its associated risk factors. Myocardial infarction in the young poses a particular challenge, as the disease is less likely, due to atherosclerosis. We report the case of a 37-year-old female patient who presented with ST segment elevation anterolateral AMI. The only abnormality on routine blood investigation was raised hemoglobin and hematocrit. After further testing, she was diagnosed according to the World Health Organization (WHO) criteria with polycythemia vera. This case illustrates the importance of recognizing polycythemia vera as an important cause of thrombosis, which can present initially as AMI, and to emphasize the early recognition of the disease in order to initiate appropriate management strategies.

Chronic myeloproliferative diseases

The chronic myeloproliferative disorders are a group of diseases in which there is an increased proliferation of one or more subtypes of myeloid cells; they include essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). In ET and PV the main neurologic manifestations are headaches, dizziness and macro- and microvascular, both venous and arterial, thrombosis and intracranial hemorrhages. Paresthesias and chorea also occur in PV. In PMF neurologic complications are very rare and consist predominantly of spinal cord compression by extramedullary hematopoiesis tissue.

Inferior vena cava thrombosis and its relationship with the JAK2V617F mutation and chronic myeloproliferative disease

BACKGROUND

Splanchnic vein thrombosis (SVT) is a typical manifestation of polycythaemia vera (PV) or essential thrombocythaemia (ET). The recently discovered JAK2V617F somatic mutation is closely associated with chronic myeloproliferative disease (CMD). We investigated whether thrombosis involving the inferior vena cava (IVC) is also related to the JAK2V617F mutation or CMD.

METHODS

Blood samples were obtained from 40 IVC thrombosis patients. Fifty-three patients with isolated lower extremity deep vein thrombosis (LE-DVT) and 20 SVT patients served as controls. The presence of the JAK2V617F mutation was assessed by real-time polymerase chain reaction (RT-PCR).

RESULTS

The JAK2V617F allele was not detected in any of the IVC thrombosis patients but was detected in one patient (2%) with isolated LE-DVT. However, the mutation-carrying patient did not exhibit symptoms of CMD. Even after an observation period of 30months, the patient's complete blood cell count did not exhibit any pathology. In contrast, the JAK2V617F allele was detected in four patients with SVT (20%) and CMD.

CONCLUSION

According to our data, there is no evidence that IVC thrombosis is associated with the JAK2V617F mutation or the presence of chronic myeloproliferative disease.

Polycythemia and chorea

Polycythemia vera is a sporadic myeloproliferative disorder of increased red blood cell mass affecting multiple organ systems. Associated thrombosis, hemorrhaging, and hyperviscosity commonly result in neurological manifestations, sometimes in the form of chorea and ballism. Resultant choreiform movements have been mainly described as generalized with orofaciolingual and appendicular muscle involvement, hypotonia, and hyporeflexia. Chorea has also been uncommonly reported as arising from secondary causes of polycythemia; however, the underlying pathophysiology has not been clearly elucidated. Proposed mechanisms for basal ganglia dysfunction include hypoperfusion due to venous stasis, receptor hypersensitivity in a setting of reduced catecholamine levels, and altered platelet dopamine metabolism. Magnetic resonance imaging and single-photon emission computed tomography perfusion studies have failed to reveal an anatomical or physiological basis for polycythemia vera-associated chorea, yet rare pathological examinations of deceased patients have shown signs of cerebral venous thrombosis and perivenous demyelination. Administration of neuroleptics may suppress abnormal choreiform movement; however, effective management of polycythemia vera requires serial venesections in conjunction with chemotherapy. Appropriate treatment may prolong survival to more than 10 years, although chorea may spontaneously remit, re-emerge with resurgence of disease, or continue indefinitely despite maintenance therapy.

Article Commentary: Symptomatic Splenomegaly in Polycythemia Vera: A Review of the Indications for Splenectomy and Perioperative Considerations

Polycythemia vera is a condition that surgeons do not commonly encounter. Advances in medical management have largely led to avoidance of surgical intervention in most patients. Indications and timing of splenectomy have been the subject of debate since the disease was first described in the late 19th century. Though anemia and thrombocytopenia associated with polycythemia vera only transiently respond to splenectomy, painful splenomegaly with infarction or compression of surrounding viscera are presently accepted indications for surgery. Special consideration must be given to polycythemia vera patients both preoperatively and postoperatively due to altered coagulation and anatomy. We present a review of the pathophysiology, medical treatment, indications for surgical intervention, and perioperative considerations for polycythemia vera.

The implication of identifying JAK2 ( V617F ) in myeloproliferative neoplasms and myelodysplastic syndromes with bone marrow fibrosis

The myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS) occasionally demonstrate overlapping morphological features including hypercellularity, mild/nonspecific dysplastic changes and variable bone marrow fibrosis. Thus, when the associated bone marrow fibrosis results in a suboptimal specimen for morphological evaluation, the descriptive diagnosis "fibrotic marrow with features indeterminate for MDS versus MPN" is often applied. The JAK2 ( V617F ) mutation was recently shown to be frequently identified in MPN, but it is rarely present in other myeloid disorders. However, the diagnostic utility of JAK2 ( V617F ) screening in hypercellular bone marrow specimens with fibrosis has not been previously investigated. Using a real-time polymerase chain reaction melting-curve assay capable of detecting JAK2 ( V617F ) in archived fixed materials, we retrospectively studied JAK2 ( V617F ) in 45 cases with fibrotic hypercellular bone marrow at initial presentation, including 19 cases initially described as "with features indeterminate for MDS versus MPN". These 19 cases were reclassified into more specific categories of MDS (n = 14) or MPN (n = 5) based on the availability of subsequent clinical data and/or bone marrow examinations. The JAK2 ( V617F ) allele was identified in 17 out of 18 BCR/ABL gene-negative MPN cases with marrow fibrosis, whereas only wild-type alleles were identified in the remaining non-MPN cases. Importantly, JAK2 ( V617F ) alleles were seen in all five cases of "with features indeterminate for MDS versus MPN" at initial presentation that were later determined to be MPN, but they were absent in the 14 cases later determined to be MDS. Our results suggest that JAK2 ( V617F ) allele evaluation can be a useful ancillary test for discriminating MDS from MPN in specimens with bone marrow fibrosis.

Isolated monocular visual loss as an initial manifestation of polycythemia vera

A 25-year-old man developed prolonged loss of vision in the left eye. Examination revealed that visual acuity was 20/20 in the right eye and 10/20 in the left eye, with a left relative afferent pupillary defect. Fundoscopy showed multiple cotton wool spots in the left whole retina with normal optic disc. Fluorescein angiography (FA) revealed markedly delayed arterial, venous and recirculation time in the left eye without retinal arterial or venous occlusion. Bone marrow aspirate confirmed polycythemia vera. After the patient underwent phlebotomy, his visual acuity markedly improved and cotton wool spots in the retina disappeared. On follow-up FA, delayed arterial and venous filling, and recirculation time also became normalized. This case suggests that ischemic damage of the retina due to the great viscosity of blood may be a possible mechanism of monocular visual loss in polycythemia vera. Clinicians should be aware that isolated monocular visual loss may be an initial manifestation of polycythemia vera, since if untreated, polycythemia vera carries a high risk of permanent complications due to intravascular thrombosis.

Switch in X-inactivation in a JAK2 V617F-negative case of polycythemia vera with two acquired X-autosome translocations

We report a JAK2 V617F-negative case of polycythemia vera with two acquired balanced X-autosome translocations and no history of previous exposure to chemo/radiotherapy. The patient's first clone carried a novel translocation t(X;15)(q24;q13) as a sole abnormality. The second clone exhibited an additional translocation, t(X;20)(q13;q13.3), which is a rare recurrent abnormality in myeloid malignancies. This is the first report of a hematological disorder with both X chromosomes being translocated. Late replication studies revealed a switch in X-inactivation from the X chromosome involved in t(X;15) (first clone) to the X chromosome involved in the t(X;20)(q13;q13.3) (second clone). The inactivation of the translocated X chromosomes could provide potential for the inactivation of the adjacent autosomal regions, resulting in epigenetic gene silencing.