Multiple granulocytic sarcomas in essential thrombocythemia

Myeloid sarcoma and pathological fracture: a case report and review of literature

Myeloid sarcoma is a rare clinical entity that presents as an isolated proliferation of leukemic cells, concurrently with or at relapse of acute myeloid leukemia (AML), myelodysplastic syndromes/neoplasms (MDS), chronic myeloid leukemia (CML), and myeloproliferative neoplasm (MPN). Myeloid sarcoma disrupts the normal architecture of its surrounding tissues. When it forms in long bones, it can cause their pathological fracture. We recently experienced a rare case of MDS presenting with myeloid sarcoma in the femur that eventually resulted in its pathological fracture. Detailed chromosomal analysis of the bone marrow cells suggested emergence of myeloid sarcoma during the fast-paced progression of MDS just after acquiring trisomy 22. A comprehensive review of previous cases of myeloid sarcoma-associated pathological fracture indicated possible involvement of structural rearrangements of chromosomes 9 and 22. Management of myeloid sarcoma should continue to improve, and clinicians should note that myeloid sarcoma with specific chromosomal alterations needs extra medical attention to prevent pathological fracture.

Myeloid Sarcoma of the Breast as Blast Phase of JAK2-Mutated (Val617Phe Exon 14p) Essential Thrombocythemia: A Case Report and a Systematic Literature Review

INTRODUCTION

Myeloid sarcoma (MS) is a mass-forming proliferation of myeloid blasts. Frequently, it arises as blast phase of pre-existing myeloproliferative, myelodysplastic disorders or consequent to bone marrow transplant. Its molecular characterization has become an increasingly important requirement for the diagnostic definition of this solid leukemia.

CASE PRESENTATION

Our case report concerns an MS arising in the breast of a woman with a previous diagnosis of JAK2-mutated essential thrombocythemia (Val617Phe exon 14p) mimicking, on histology, a lobular carcinoma of the breast. The immunohistochemical study of the neoplasm provided the key that solved the diagnostic doubt and the immunohistochemical evaluation of NPM protein expression, which turn out to be negative, provided a clear indication on the molecular status and prognosis of the disease. A year later, the neoplasm relapsed in the pelvic area.

DISCUSSION

This diagnostic challenge led us to review the literature of the past 10 years concerning MS of the breast. To the best of our knowledge, this was the first case of MS of the breast occurring in a patient with a history of essential thrombocythemia and recurred in the pelvic region.

Epigenomic analysis of KLF1 haploinsufficiency in primary human erythroblasts

Haploinsufficiency for the erythroid-specific transcription factor KLF1 is associated with hereditary persistence of fetal hemoglobin (HPFH). Increased HbF ameliorates the symptoms of β-hemoglobinopathies and downregulation of KLF1 activity has been proposed as a potential therapeutic strategy. However, the feasibility of this approach has been challenged by the observation that KLF1 haploinsufficient individuals with the same KLF1 variant, within the same family, display a wide range of HbF levels. This phenotypic variability is not readily explained by co-inheritance of known HbF-modulating variants in the HBB, HBS1L-MYB and/or BCL11A loci. We studied cultured erythroid progenitors obtained from Maltese individuals in which KLF1 p.K288X carriers display HbF levels ranging between 1.3 and 12.3% of total Hb. Using a combination of gene expression analysis, chromatin accessibility assays and promoter activity tests we find that variation in expression of the wildtype KLF1 allele may explain a significant part of the variability in HbF levels observed in KLF1 haploinsufficiency. Our results have general bearing on the variable penetrance of haploinsufficiency phenotypes and on conflicting interpretations of pathogenicity of variants in other transcriptional regulators such as EP300, GATA2 and RUNX1.