Von Recklinghausen neurofibromatosis and hematologic malignancies: 2 case reports in adulthood

Diagnostic Approaches to Investigate JAK2-Unmutated Erythrocytosis Based on a Single Tertiary Center Experience

INTRODUCTION

Erythrocytosis is attributed to various clinical and molecular factors. Many cases of JAK2-unmutated erythrocytosis remain undiagnosed. We investigated the characteristics and causes of JAK2-unmutated erythrocytosis.

METHODS

We assessed the clinical and laboratory results of patients with erythrocytosis without JAK2 mutations and performed targeted next-generation sequencing (NGS) panels for somatic and germline mutations.

RESULTS

In total, 117 patients with JAK2-unmutated erythrocytosis were included. The median hemoglobin and hematocrit levels were 17.9 g/dL and 53.4%, respectively. Erythropoietin levels were not below the reference range. Thrombotic events were reported in 17 patients (14.5%). Among JAK2-unmutated patients, 44 had undergone targeted panel sequencing consisting of myeloid neoplasm-related genes, and 16 had one or more reportable variants in ASXL1 (5/44), TET2, CALR, FLT3, and SH2B3 (2/44). Additional testing for germline causes revealed eight variants in seven genes in eight patients, including NF1, BPGM, EPAS1, PIEZO1, RHAG, SH2B3, and VHL genes. One NF1 pathogenic, one BPGM likely pathogenic, and six variants of undetermined significance were detected.

CONCLUSION

Somatic and germline mutations were identified in 36.4% and 33.3 % of the JAK2-unmutated group; most variants had unknown clinical significance. Not all genetic causes have been identified; comprehensive diagnostic approaches are crucial for identifying the cause of erythrocytosis.

A case report of acute myeloid leukemia and neurofibromatosis 1

We report a case of a 65-year old patient affected by neurofibromatosis 1, documented by the presence of germ-line mutation on the NF1 gene, who developed various hyperproliferative malignant and benign diseases. He was brought to our attention for the diagnosis of acute myeloid leukemia revealed by major fatigue and dyspnea. The disease characteristics at diagnosis were hyperleukocytosis and complex karyotype with the inversion of the chromosome 16, classifying as a high-risk leukemia. The association between leukemia and neurofibromatosis 1 is controversial and needs to be further investigated. Nevertheless, such patients present a wide number of comorbidities that make therapeutic strategies most difficult.

Risk of leukemic transformation in PV and ET patients

Despite a prolonged survival of around 15 years linked to a prolonged complete remission induced by myelosuppression, myeloproliferative syndromes such as polycythemia vera (PV) and essential thrombosis (ET) remain at risk of lethal adverse affects such as thrombotic events and acute transformation. The major risk at diagnosis, in the absence of treatment, is essentially thrombosis. Different therapeutic trials have shown the necessity to maintain circulating blood cells (RBC and platelets counts) near normal levels to avoid thrombosis. Phlebotomies alone in PV lead in the long run to metaplasia and increased platelet counts and should only be kept for emergency cell count reduction. Myelosuppression is thus until recently the most widely accepted effective alternative. However, the effects of long term chronic administration of myelosuppresive agents needs to be analyzed and monitored as the biological changes which appear during the course of these diseases linked or not to the intrinsic clonal haematopoietic abnormality may lead to malignant transformation. Thus, alternative therapies need to be evaluated and predisposition factors taken in account.

Correction of intraoperative coagulopathy in a patient with neurofibromatosis type I with intravenous desmopressin (DDAVP)

A patient with the genetic condition neurofibromatosis type I and no known coagulopathy undergoing cesarean delivery, had diffuse uterine and surgical site bleeding that was not correctable by oxytocin, methylergonovine and PGF2 alpha. Despite good uterine tone, hemorrhage continued from the uterus and the surrounding tissues, persisting even after surgical ligation of the uterine arteries. With no change in her condition, which was behaving clinically as a coagulopathy, an infusion of desmopressin acetate (DDAVP) was begun. The patient's bleeding promptly resolved shortly after infusion of this agent. A review of relevant literature suggests that platelet reactivity of patients with neurofibromatosis type 1 is attenuated in some in vitro conditions. Thus, there may be some theoretical basis for using DDAVP in patients with neurofibromatosis type 1 who have bleeding problems with no other known source, such as in the case presented here.

Therapy-related myelodysplastic syndrome in adults with neurofibromatosis

Although an increased risk of hematologic malignancies in children with Neurofibromatosis-1 (NF-1) is well established, whether adults with NF-1 have an increased risk of such malignancies is unclear. We currently describe two adult patients with NF-1 who rapidly developed secondary myelodysplastic syndromes with abnormalities of chromosome 7 following chemotherapy for AML. We propose that adults with NF-1 also have abnormalities of hematologic progenitor cells.