A 46-year-old lady presented to the outpatient section with a four-month history of low-grade fever, abdominal distension, and early satiety. There was no pallor, icterus, lymphadenopathy, pedal edema, or other dysmorphic features. Her liver was palpable, and her spleen was 15 cm below the costal margin. The rest of the clinical examination was normal. She had anemia and leukocytosis (Hemoglobin 9.2 gm/dl, total leukocyte count 42,400/mm3, platelet count 1.8 × 109/L). Peripheral smear examination showed moderate anisopoikilocytosis, tear drop cells, schistocytes, spherocytes, nucleated RBCs, leukocytosis with immature cells, and adequate platelets. Liver and renal functions were normal, serum lactate dehydrogenase was elevated, 548 U/L (range 0–247 U/L), and an ultrasound of the abdomen revealed hepatosplenomegaly. Bone marrow aspirate was markedly dilute and aparticulate, and trephine biopsy showed a hypocellular bone marrow with 20–30% cellularity, large areas of fibrosis (WHO grade 3 fibrosis), and no granuloma [Figure 1b and c].
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Figure 1: (a) Low-power image (40×) shows fibrotic marrow with islands of residual hematopoiesis and focal osteosclerosis. (b) High power (400×) shows clusters of abnormal megakaryocytes with dilated sinuses with residual hematopoiesis and a diffuse connecting meshwork of collagen involving more than 30% of marrow spaces. (c) Reticulin and Masson’s trichrome stain showing WHO grade 3 fibrosis. (d) Karyogram showing 46, XX, del (4) (q25)[20] arrow
Conventional Karyotyping [Figure 1a] showed an abnormality on all 20 analyzed metaphases. There was a deletion of the long arm of chromosome 4 at band 4q25 in all 20 metaphases [Figure 1d]. Next-generation sequencing (NGS) revealed JAK2V617F mutation-positive (mutant allele burden 45%, overall depth 358×), and a missense variation p.Glu180Asp was detected in the Tp53 region and identified as a variant of unknown significance (VUS) [Figures 2 and 3]. A comprehensive myeloid gene panel by NGS also tested other mutations and fusions, including BCR:ABL1, CALR, MPL, TET2, ASXL1, TP53, EZH2, DNMT3A, SF3B1, SRSF2, and U2AF1, and showed no other clinically significant mutation. She was diagnosed with primary myelofibrosis (PMF) DIPPS–plus score of 3/8 (intermediate–2). She was treated with hydroxycarbamide, lenalidomide-prednisolone, and ruxolitinib afterwards. She is presently transfusion-independent with no observed regression in spleen size after three months of therapy. She is on close follow-up and is unwilling to undergo an allogeneic stem cell transplant.
Figure 2: IGHV Images depicting mutations JAK2V617F and missense mutation (variant of unknown significance) in Tp53 genes – sequence 1
Figure 3: IGHV Images depicting mutations JAK2V617F and missense mutation (variant of unknown significance) in Tp53 genes – sequence 2
PMF is a myeloproliferative neoplasm characterized by clonal expansion of aberrant immature megakaryocytes leading to the intricate milieu of marrow fibrosis, myeloid metaplasia, and splenomegaly.[1] Driver mutations like JAK2, MPL, or CALR are seen in nearly 90% of patients with PMF. Together with epigenetic dysregulations involving genes like ASXL1, TET2, DNMT3A, SRSF2, IDH1/2, EZH2, and U2AF1, they play an essential role in the disease pathogenesis.[2] Cytogenetic anomalies are seen in approximately 34% of patients.[3] They have a prognostic significance, and high-risk cytogenetic aberrations are often associated with rapid disease progression.
The most frequent cytogenetic aberrations include deletions of chromosomes 13q, 20q, trisomies 8 and 9, and partial trisomy 1q.[3] Anomalies involving chromosome 4 are infrequent in PMF, and deletions involving the long arm of chromosome 4 have never been described earlier. We describe the first case of JAK2-positive PMF with deletion 4q25 in all 20 metaphases.
Germline mutation involving deletion 4q25 is also known to be associated with Axenfeld–Rieger syndrome.[4] Retrospectively we examined the patient, her son, and her next of kin. There were no dysmorphic features on clinical examination or abnormal behavioral patterns observed in the patient or her family. Since the patient was 46 years old with no significant past medical history of any illness or abnormal behavior, further evaluation for germline mutations was not done.
In their extensive literature review, Hussein et al.[5] reported a few cases of monosomy 4 and trisomy 4. It is also well-established that mutations involving 4q24 are associated with pathogenic TET2 mutations.[6] However, cytogenetic anomaly involving deletion 4q25 is a unique entity not described earlier in PMF. Moreover, the missense mutation identified in the Tp53 region is a variant of unknown significance with indeterminate clinical significance.
In conclusion, to the best of our knowledge, this is the first case of deletion 4q25 in a patient with JAK2 V617F mutation-positive PMF without other hematological malignancies. Further studies are needed to confirm the nature and extent of pathogenicity associated with this mutation and the prognostic impact of deletion 4q25 in PMF.
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The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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REFERENCES
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3. Tefferi A. Primary myelofibrosis:2021 update on diagnosis, risk-stratification and management. Am J Hematol 2021;96:145–62.
4. Heithaus JL, Twyman KA, Batanian JR. A rare recurrent 4q25 proximal deletion not involving the PITX2 gene:A genomic disorder distinct from Axenfeld-Rieger syndrome. Mol Syndromol 2016;7:138–43.
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