Shared cell of origin in a patient with Erdheim-Chester disease and acute myeloid leukemia

Co-occurrence of Erdheim-Chester disease and clonally evolving acute myeloid leukemia with FLT3-ITD and PTPN11 mutations

Erdheim-Chester disease (ECD) is a rare histiocytosis that tends to co-exist with other myeloid malignancies. Here, we use genetic and transcriptomic sequencing to delineate a case of co-occurring BRAFV600E-mutated ECD and acute myeloid leukemia (AML), followed by AML remission and relapse. The AML relapse involved the extinction of clones with KMT2A-AFDN and FLT3-ITD, and the predominance of PTPN11-mutated subclones with distinct transcriptomic features. This case report has highlighted the screening for other myeloid malignancies at the diagnosis of ECD and the clinical significance of PTPN11-mutated AML subclones that require meticulous monitoring.

Genetic characterization of primary and metastatic high-grade serous ovarian cancer tumors reveals distinct features associated with survival

High-grade serous ovarian cancer (HGSC) is the most lethal histotype of ovarian cancer and the majority of cases present with metastasis and late-stage disease. Over the last few decades, the overall survival for patients has not significantly improved, and there are limited targeted treatment options. We aimed to better characterize the distinctions between primary and metastatic tumors based on short- or long-term survival. We characterized 39 matched primary and metastatic tumors by whole exome and RNA sequencing. Of these, 23 were short-term (ST) survivors (overall survival (OS) < 3.5 years) and 16 were long-term (LT) survivors (OS > 5 years). We compared somatic mutations, copy number alterations, mutational burden, differential gene expression, immune cell infiltration, and gene fusion predictions between the primary and metastatic tumors and between ST and LT survivor cohorts. There were few differences in RNA expression between paired primary and metastatic tumors, but significant differences between the transcriptomes of LT and ST survivors in both their primary and metastatic tumors. These findings will improve the understanding of the genetic variation in HGSC that exist between patients with different prognoses and better inform treatments by identifying new targets for drug development.

Case report: Common clonal origin of concurrent langerhans cell histiocytosis and acute myeloid leukemia

Langerhans cell histiocytosis (LCH) and acute myeloid leukemia (AML) are distinct entities of blood neoplasms, and the exact developmental origin of both neoplasms are considered be heterogenous among patients. However, reports of concurrent LCH and AML are rare. Herein we report a novel case of concurrent LCH and AML which shared same the driver mutations, strongly suggesting a common clonal origin.An 84-year-old female presented with cervical lymphadenopathy and pruritic skin rash on the face and scalp. Laboratory tests revealed pancytopenia with 13% of blasts, elevated LDH and liver enzymes, in addition to generalised lymphadenopathy and splenomegaly by computed tomography. Bone marrow specimens showed massive infiltration of MPO-positive myeloblasts, whereas S-100 and CD1a positive atypical dendritic cell-like cells accounted for 10% of the atypical cells on bone marrow pathology, suggesting a mixture of LCH and AML. A biopsy specimen from a cervical lymph node and the skin demonstrated the accumulation of atypical cells which were positive for S-100 and CD1a. LCH was found in lymph nodes, skin and bone marrow; AML was found in peripheral blood and bone marrow (AML was predominant compared with LCH in the bone marrow).

Next generation sequencing revealed four somatic driver mutations (NRAS-G13D, IDH2-R140Q, and DNMT3A-F640fs/-I715fs), equally shared by both the lymph node and bone marrow, suggesting a common clonal origin for the concurrent LCH and AML. Prednisolone and vinblastine were initially given with partial response in LCH; peripheral blood blasts also disappeared for 3 months. Salvage chemotherapy with low dose cytarabine and aclarubicin were given for relapse, with partial response in both LCH and AML. She died from pneumonia and septicemia on day 384. Our case demonstrates a common cell of origin for LCH and AML with a common genetic mutation, providing evidence to support the proposal to classify histiocytosis, including LCH, as a myeloid/myeloproliferative malignancy.

MicroRNA-15a-5p acts as a tumor suppressor in histiocytosis by mediating CXCL10-ERK-LIN28a-let-7 axis

Erdheim-Chester disease (ECD) is characterized by excessive production and accumulation of histiocytes within multiple tissues and organs. ECD patients harbor recurrent mutations of genes associated with the RAS/RAF/MEK/ERK signaling pathway, particularly, the BRAFV600E mutation. Following our previous finding that miR-15a-5p is the most prominently downregulated microRNA in ECD patients compared to healthy individuals, we elucidated its role in ECD pathogenesis. Bioinformatics analysis followed by a luciferase assay showed that chemokine ligand 10 (CXCL10) is a target gene regulated by miRNA-15a-5p. This was confirmed in 24/34 ECD patients that had low expression of miR-15a-5p concurrent with upregulated CXCL10. Overexpression of miR-15a-5p in cell lines harboring BRAF or RAS mutations (Ba/F3, KG-1a and OCI-AML3) resulted in CXCL10 downregulation, followed by LIN28a and p-ERK signaling downregulation and let-7 family upregulation. Overexpression of miR-15a-5p inhibited cell growth and induced apoptosis by decreasing Bcl-2 and Bcl-xl levels. Analysis of sequential samples from 7 ECD patients treated with MAPK inhibitors (vemurafenib/cobimetinib) for 4 months showed miR-15a-5p upregulation and CXCL10 downregulation. Our findings suggest that miR-15a-5p is a tumor suppressor in ECD through the CXCL10-ERK-LIN28a-let7 axis, highlighting another layer of post-transcriptional regulation in this disease. Upregulation of miR-15a-5p in ECD patients may have a potential therapeutic role.

Sustained, complete response to pexidartinib in a patient with CSF1R-mutated Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a histiocytic neoplasm that predominantly harbors mitogen-activated protein kinase (MAPK) pathway variants. MAPK inhibitors typically are effective treatments, but mutations outside the MAPK pathway, such as CSF1R variants, may cause refractory ECD. We describe a patient with a novel somatic mutation in CSF1R (CSF1R^{R549_E554delinsQ} ) that resulted in refractory ECD affecting the central nervous system. Cell model studies, RNA sequencing analysis, and in silico protein modeling suggested that she had a gain-of-function mutation occurring in a region critical for autoinhibition. The patient was treated with pexidartinib, a CSF1R inhibitor, and has had a complete clinical and metabolic response lasting more than 1.5 years to date. To our knowledge, this is the first report to describe successful treatment of a patient with ECD by using an agent that specifically targets CSF1R. This case also highlights the critical role of individualized molecular profiling to identify novel therapeutic targets in ECD.

Histiocytosis

Histiocytoses constitute a heterogeneous group of rare disorders, characterised by infiltration of almost any organ by myeloid cells with diverse macrophage or dendritic cell phenotypes. Histiocytoses can start at any age. Diagnosis is based on histology in combination with appropriate clinical and radiological findings. The low incidence and broad spectrum of clinical manifestations often leads to diagnostic delay, especially for adults. In most cases, biopsy specimens infiltrated by histiocytes have somatic mutations in genes activating the MAP kinase cell-signalling pathway. These mutations might also be present in blood cells and haematopoietic progenitors of patients with multisystem disease. A comprehensive range of investigations and molecular typing are essential to accurately predict prognosis, which can vary from spontaneous resolution to life-threatening disseminated disease. Targeted therapies with BRAF or MEK inhibitors have revolutionised salvage treatment. However, the type and duration of treatment are still debated, and the prevention of neurological sequelae remains a crucial issue.

Erdheim-Chester disease: a comprehensive review from the ophthalmologic perspective

Erdheim-Chester disease (ECD) is a rare clonal histiocytic neoplasm with less than 1200 documented cases to date. The disease is life-threatening and difficult to recognize, although increasing awareness as well as the integration of clinical, imaging, pathology information , and genetic studies have led to a recent exponential increase in new reported cases. ECD affects multiple organs and systems, including skeletal, neurologic, and cardiovascular. Pulmonary, retroperitoneal, and cutaneous lesions have also been reported in various combinations. Until the discovery that more than half of ECD patients harbor the BRAF-V600E mutation or other mutations in the mitogen-activated protein kinase (MAPK) and RAS pathways, Interferon-a was the first-line treatment. Nowadays BRAF and MEK-inhibitors targeted therapies are the mainstay of treatment. Ophthalmologic involvement occurs in 25% -30% of ECD cases, usually in the form of orbital involvement presenting with exophthalmos and ophthalmoplegia. Other ophthalmologic manifestations include palpebral xanthelasmas, anterior uveitis and vitritis, optic disk edema, choroidal infiltration, recurrent serous retinal detachment, retinal drusen-like deposits and retinal pigment epithelial changes. ECD patients can also present with ocular symptoms as a result of adverse effects of the treatment regimens. In some cases with smoldering or protean symptoms, the emergence of eye manifestations triggered the diagnosis. Ophthalmologists have to be aware of the disease, recognize the constellation of ECD symptoms, and contribute to the diagnosis, treatment, and follow-up of ECD patients.

Atypical cutaneous histiocytic eruption in a patient with chronic myelomonocytic leukemia: A case report

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell malignancy with features of both a myeloproliferative neoplasm and a myelodysplastic syndrome. We present a case of 72-year-old man with CMML who presented with generalized hemorrhagic papules and plaques which on histopathology showed a peculiar infiltrate of atypical mature histiocytes. The immunohistochemical markers for Langerhans cells, indeterminate dendritic cells, and plasmacytoid dendritic cells were negative. Next generation sequencing performed on the paraffin block of the leg biopsy specimen revealed identical ASXL1, SRSF2, and KRAS mutations as seen in the CMML clone of the peripheral blood. Along with recent literature, this case illustrates the spectrum of histiocytic and dendritic cell proliferations in CMML, many of which may be clonally related to the hematopoietic malignancy.

Spectrum of histiocytic neoplasms associated with diverse haematological malignancies bearing the same oncogenic mutation

Histiocytic disorders are a spectrum of rare diseases characterised by the accumulation of macrophage-, dendritic cell-, or monocyte-differentiated cells in various tissues and organs. The discovery of recurrent genetic alterations in many of these histiocytoses has led to their recognition as clonal neoplastic diseases. Moreover, the identification of the same somatic mutation in histiocytic lesions and peripheral blood and/or bone marrow cells from histiocytosis patients has provided evidence for systemic histiocytic neoplasms to originate from haematopoietic stem/progenitor cells (HSPCs). Here, we investigated associations between histiocytic disorders and additional haematological malignancies bearing the same genetic alteration(s) using the nationwide Dutch Pathology Registry. By searching on pathologist-assigned diagnostic terms for the various histiocytic disorders, we identified 4602 patients with a putative histopathological diagnosis of a histiocytic disorder between 1971 and 2019. Histiocytosis-affected tissue samples of 187 patients had been analysed for genetic alterations as part of routine molecular diagnostics, including from nine patients with an additional haematological malignancy. Among these patients, we discovered three cases with different histiocytic neoplasms and additional haematological malignancies bearing identical oncogenic mutations, including one patient with concomitant KRAS p.A59E mutated histiocytic sarcoma and chronic myelomonocytic leukaemia (CMML), one patient with synchronous NRAS p.G12V mutated indeterminate cell histiocytosis and CMML, and one patient with subsequent NRAS p.Q61R mutated Erdheim-Chester disease and acute myeloid leukaemia. These cases support the existence of a common haematopoietic cell-of-origin in at least a proportion of patients with a histiocytic neoplasm and additional haematological malignancy. In addition, they suggest that driver mutations in particular genes (e.g. N/KRAS) may specifically predispose to the development of an additional clonally related haematological malignancy or secondary histiocytic neoplasm. Finally, the putative existence of derailed multipotent HSPCs in these patients emphasises the importance of adequate (bone marrow) staging, molecular analysis and long-term follow-up of all histiocytosis patients.

Erdheim-Chester Disease and Acute Myeloid Leukemia with Mutated NPM1 in a Patient with Clonal Hematopoiesis: A Case Report

Background

Erdheim–Chester Disease (ECD) is a clonal non-Langerhans histiocytosis, classified as a macrophage-dendritic cell neoplasm in the 2016 WHO classification. The exact cell of origin of ECD is unknown, although some limited evidence suggests that it arises from myeloid progenitors.

Case Presentation

A 43-year-old patient, diagnosed with BRAF^V600E mutated ECD, developed NPM1⁺/FLT3⁺ acute myeloid leukemia (AML) with wild-type BRAF, 15 months after the initial ECD diagnosis. The patient received intensive chemotherapy plus midostaurin, followed by midostaurin maintenance. Six months into maintenance, the patient remains in complete remission with low-level measurable residual disease, whereas ECD shows a sustained partial metabolic response. Molecular karyotype at several distinct timepoints, namely ECD diagnosis, AML diagnosis, and following treatment of AML, highlighted a molecular signature, indicative of a persistent, underlying clonal hematopoiesis.

Conclusion

This case report suggests that ECD and AML might represent an expansion of two distinct clones in a background of clonal hematopoiesis, indicating their shared origin. Moreover, molecular karyotype might serve as a strong, inexpensive tool for revealing clonal hematopoiesis in cases of negative targeted next-generation sequencing. Finally, the moderate response of ECD to midostaurin suggests that kinase inhibition might have a potential role in ECD treatment.