Cranial Bone Marrow Research Articles

Brain microbleeds resulting from presumed extensive fat emboli in a patient with bone marrow necrosis following a sickle cell disease vaso-occlusive crisis.

Acute manifestations of sickle cell disease (SCD) are numerous and multisystemic.Cerebral fat embolism (CFE) is a rare but serious complication of SCD caused by bone marrow necrosis (BMN) during vaso-occlusive crises (VOC). We present the case of a41-year-old man with SCD who developed severe VOC and multi-organ dysfunction.He subsequently experienced neurological deterioration with decreased consciousness and diffuse encephalopathy on serial electroencephalograms. Bone marrow aspiration confirmed BMN. Brain MRI revealed extensive diffuse leukoencephalopathy, vasogenic and cytotoxic edema in the white matter, patchy edema in the cranial vault bone marrow on fat-suppressed FLAIR sequence (a finding consistent with the confirmed BMN), and multiple cerebral microbleeds on susceptibility-weighted imaging consistent with CFE. The management of acute neurological complications of SCD varies depending on the specific complication. Brain MRI plays a crucial role in the accurate diagnosis of these complications to guide appropriate treatment.

Cranioencephalic functional lymphoid units in glioblastoma.

The ecosystem of brain tumors is considered immunosuppressed, but our current knowledge may be incomplete. Here we analyzed clinical cell and tissue specimens derived from patients presenting with glioblastoma or nonmalignant intracranial disease to report that the cranial bone (CB) marrow, in juxtaposition to treatment-naive glioblastoma tumors, harbors active lymphoid populations at the time of initial diagnosis. Clinical and anatomical imaging, single-cell molecular and immune cell profiling and quantification of tumor reactivity identified CD8+ T cell clonotypes in the CB that were also found in the tumor. These were characterized by acute and durable antitumor response rooted in the entire T cell developmental spectrum. In contrast to distal bone marrow, the CB niche proximal to the tumor showed increased frequencies of tumor-reactive CD8+ effector types expressing the lymphoid egress marker S1PR1. In line with this, cranial enhancement of CXCR4 radiolabel may serve as a surrogate marker indicating focal association with improved progression-free survival. The data of this study advocate preservation and further exploitation of these cranioencephalic units for the clinical care of glioblastoma.

Emergence of the brain-border immune niches and their contribution to the development of neurodegenerative diseases.

Historically, the central nervous system (CNS) was regarded as 'immune-privileged', possessing its own distinct immune cell population. This immune privilege was thought to be established by a tight blood-brain barrier (BBB) and blood-cerebrospinal-fluid barrier (BCSFB), which prevented the crossing of peripheral immune cells and their secreted factors into the CNS parenchyma. However, recent studies have revealed the presence of peripheral immune cells in proximity to various brain-border niches such as the choroid plexus, cranial bone marrow (CBM), meninges, and perivascular spaces. Furthermore, emerging evidence suggests that peripheral immune cells may be able to infiltrate the brain through these sites and play significant roles in driving neuronal cell death and pathology progression in neurodegenerative disease. Thus, in this review, we explore how the brain-border immune niches may contribute to the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). We then discuss several emerging options for harnessing the neuroimmune potential of these niches to improve the prognosis and treatment of these debilitative disorders using novel insights from recent studies.

Lateralized response of skull bone marrow via osteopontin signaling in mice after ischemia reperfusion

Skull bone marrow is thought to be an immune tissue closely associated with the central nervous system (CNS). Recent studies have focused on the role of skull bone marrow in central nervous system disorders. In this study, we performed single-cell RNA sequencing on ipsilateral and contralateral skull bone marrow cells after experimental stroke and then performed flow cytometry and analysis of cytokine expression. Skull marrow showed lateralization in response to stroke. Lateralization is demonstrated primarily by the proliferation and differentiation of myeloid and lymphoid lineage cells in the skull bone marrow adjacent to the ischemic region, with an increased proportion of neutrophils compared to monocytes. Analysis of chemokines in the skull revealed marked differences in chemotactic signals between the ipsilateral and contralateral skull, whereas sympathetic signals innervating the skull did not affect cranial bone marrow lateralization. Osteopontin (OPN) is involved in region-specific activation of the skull marrow that promotes inflammation in the meninges, and inhibition of OPN expression improves neurological function.Graphical

A single-cell transcriptomic atlas characterizes age-related changes of murine cranial stem cell niches.

The craniofacial bones provide structural support for the skull and accommodate the vulnerable brain tissue with a protective cavity. The bone tissue undergoes constant turnover, which relies on skeletal stem cells (SSCs) and/or mesenchymal stem cells (MSCs) and their niches. SSCs/MSCs and their perivascular niche within the bone marrow are well characterized in long bones. As for cranial bones, besides bone marrow, the suture mesenchyme has been identified as a unique niche for SSCs/MSCs of craniofacial bones. However, a comprehensive study of the two different cranial stem cell niches at single-cell resolution is still lacking. In addition, during the progression of aging, age-associated changes in cranial stem cell niches and resident cells remain uncovered. In this study, we investigated age-related changes in cranial stem cell niches via single-cell RNA sequencing (scRNA-seq). The transcriptomic profiles and cellular compositions have been delineated, indicating alterations of the cranial bone marrow microenvironment influenced by inflammaging. Moreover, we identified a senescent mesenchymal cell subcluster and several age-related immune cell subclusters by reclustering and pseudotime trajectory analysis, which might be closely linked to inflammaging. Finally, differentially expressed genes (DEGs) and cell-cell communications were analyzed during aging, revealing potential regulatory factors. Overall, this work highlights the age-related changes in cranial stem cell niches, which deepens the current understanding of cranial bone and suture biology and may provide therapeutic targets for antiaging and regenerative medicine.

Viral infection in the brain induces priming and maintenance of a novel antigen specific CD8 T cell population within the bone marrow that dysregulates the stem cell niche

Abstract Bone marrow is a primary immune organ responsible for stem cell maintenance and hematopoiesis. While the bone marrow niche is mainly studied in the context of hematopoiesis, aging, and mechanisms underlying stem cell and plasma cell survival, changes of the niche during brain viral infections and primary T cell responses is unknown. Intracranial infection with the neurotropic Theiler’s Murine Encephalomyelitis Virus (TMEV) results in an acute infection in the C57BL/6 mouse which is cleared 30 days post infection due to generation of an antigen specific CD8 T cell response raised against the immunodominant epitope VP2 121–130. We determined that 7–10% of CD8 T cells present in the sternal and femoral bone marrows and 15–20% in the cranial bone marrow were antigen specific 7 days post intracranial TMEV infection. Over 70% of these CD8 T cells were located outside of the vasculature as determined by IV labeling. Importantly, continuous treatment with FTY720, which sequesters T cells outside of the blood, did not eliminate antigen specific CD8 T cells in any bone marrow compartment. CD8 T cells in the bone marrow established durable memory following viral clearance and were reactivated upon cognate antigen reencounter. Both acute TMEV infection and antigen specific reactivation caused an increase in lineage −, Sca-1 +, ckit +(LSK) cells in the bone marrow. This LSK dysregulation was abrogated upon CD8 T cell depletion. We conclude that brain viral infections induce in situ effector and memory T cell responses within the bone marrow compartment. Both acute and memory recall CD8 T cell responses cause stem cell dysregulation. Our data hence paves the way for crucial studies of bone marrow resident antigen specific CD8 T cells in health and disease. Supported by grants from NIH (K99NS117799-01A1 (KA), R01NS103212 (AJJ), and RF1NS122174(AJJ)

Progressive skeletal defects caused by Kindlin3 deficiency, a model of autosomal recessive osteopetrosis in humans.

The cellular and molecular mechanisms of bone development and homeostasis are clinically important, but not fully understood. Mutations in integrins and Kindlin3 in humans known as Leukocyte adhesion deficiencies (LAD) cause a wide spectrum of complications, including osteopetrosis. Yet, the rarity, frequent misdiagnosis, and lethality of LAD preclude mechanistic analysis of skeletal abnormalities in these patients. Here, using inducible and constitutive tissue-specific Kindlin3 knockout (K3KO) mice, we show that the constitutive lack of embryonic-Kindlin3 in myeloid lineage cells causes growth retardation, edentulism, and skull deformity indicative of hydrocephaly. Micro-CT analysis revealed craniosynostosis, choanal stenosis, and micrognathia along with other skeletal abnormalities characteristic of osteopetrosis. A marked progression of osteosclerosis occurs in mature to middle-aged adults, resulting in the narrowing of cranial nerve foramina and bone marrow cavities of long bones. However, postnatal-Kindlin3 is less critical for bone remodeling and architecture. Thus, myeloid Kindlin3 is essential for skeletal development and its deficiency leads to autosomal recessive osteopetrosis (ARO). The study will aid in the diagnosis, management, and treatment choices for patients with LAD-III and ARO.

Phenotypic and Functional Characterizations of Mesenchymal Stem/Stromal Cells Isolated From Human Cranial Bone Marrow.

Mesenchymal stem/stromal cells (MSCs) are adult stem cells that were originally isolated from bone marrow. In contrast to long bone-derived MSCs that have been extensively characterized, our knowledge regarding to MSCs isolated from flat bones (e.g., cranial bones) remain less clear. In this study, MSCs were purified from human cranial bone marrow (CB-MSCs) and their transdifferentiation capacity and immunomodulatory functions were further characterized. Phenotypic analysis of CB-MSCs demonstrated high expression of CD73, CD90, and CD105 while negative for CD14, CD34, and HLA-DR. Further in vitro differentiation assay shown that CB-MSCs capable of differentiating into cell types of mesenchymal origin (i.e., adipocytes, osetoblasts, and chondrocytes) and collectively, these results indicated that cells isolated from cranial bone marrow in this study are bona fide MSCs according to the minimal criteria proposed by the International Society for Cellular Therapy. Following in vitro expansion, single colony-derived CB-MSCs (scCB-MSCs) were obtained and confocal microscopy analysis further revealed functional heterogeneity within primary CB-MSCs. Specifically, obtained scCB-MSCs exhibited GABA progenitor features, as determined by olig2 and nestin. As expect, scCB-MSCs were readily induced to differentiate into GABAergic neuron-like cells. Furthermore, immunomodulatory roles of scCB-MSCs were evaluated following co-culture with human peripheral blood lymphocytes and results shown that co-culturing with scCB-MSCs significantly suppressed lymphocyte proliferation and promoted differentiation of lymphocytes into regulatory T cells but not Th1/Th17 phenotype. Overall, our results indicated that CB-MSCs exhibited clonal heterogeneity with marked propensity to differentiate into neural-like cells and this might represent promising candidates for the treatment of neurodegenerative diseases.

Magnetic resonance imaging study of normal cranial bone marrow conversion at high altitude.

To use conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) to investigate the effects of long-term hypoxia on cranial bone marrow conversion in healthy people at high altitudes. A total of 1,130 individuals were selected from altitudinal areas of 2,000-3,000, 3,100-4,000, and >4,100 m. Each altitude range was divided into 5 age groups: 0-5, 6-14, 15-29, 30-49, and ≥50 years. Firstly, cranial bone marrow typing of the participants in each altitude range was performed on sagittal T1-weighted images (T1WI) according to the average diploe thickness and signal intensity of the normal skull, and the relationship between bone marrow conversion and age was analyzed. Secondly, the apparent diffusion coefficient (ADC) values of the frontal bone, parietal bone, occipital bone, and temporal bone were measured in the DWI post-processing workstation and statistical methods were used to analyze whether different altitudinal gradients and long-term hypoxic environment had any effect on cranial bone marrow conversion. There was a positive correlation between bone marrow type and age in the healthy populations at all 3 levels of altitude (P<0.05). The average thickness of the cranial diploe also positively correlated with age (P<0.05); in the age ranges of 30-49 and ≥50 years, the ADC values of the occipital and temporal bone marrow positively correlated with increasing altitude (P<0.05). The cranial bone marrow of normal people at high altitudes changes from Type I to Type IV with increasing age and under the influence of long-term chronic hypoxia. The bone marrow of the occipital and temporal bones of healthy people aged 30-49 and ≥50 years showed erythromedularization during the process of Type III and IV bone marrow conversion.

Natural History of Type II Autosomal Dominant Osteopetrosis: A Single Center Retrospective Study.

BackgroundAutosomal dominant osteopetrosis II (ADO II, MIM166600) is a sclerosing bone disorder caused by CLCN7 mutation. The main clinical characteristics include minor trauma-related fracture and hip osteoarthritis, whereas cranial nerve palsy and bone marrow failure rarely develop. Although it is generally believed that ADO II has a relatively benign course, the natural course of the disease in Chinese patients remains unclear.Materials and MethodsThirty-six patients diagnosed with ADO II in Shanghai Jiao Tong University Affiliated Sixth People’s Hospital from 2008 to 2021 were studied retrospectively. Among them, 15 patients were followed for an average of 6.3 years (1-14 years).ResultsIn this study, minor trauma-related fractures of the limb were the most typical clinical manifestations. Visual loss (1/36) and bone marrow failure (2/36), was rare in this study. The condition of ADO II seems to be stable in most patients. There were no correlations between markedly elevated bone mineral density (BMD) and minor trauma-related fractures. In total, 21 diseases causing mutations were detected. Among them, the mutation c.2299C>T (p.Arg767Trp) was the most common (16.67%), and mutation c.937G>A [p.(Glu313Lys)] was associated with severe fractures, haematological defects and cranial palsy.ConclusionsMinor trauma-related fracture is the most typical clinical manifestation of ADO II and always occurs in. The mutation c.2299C>T (p.Arg767Trp) is in general a relatively common variant, while the mutation c.937G>A [p.(Glu313Lys)] seems to be associated with severe phenotype. In our study, ADO II seems to remain stable over time.

Ultra-structural morphology analysis of human cranial bone marrow mesenchymal stromal cells during neural differentiation

Neural differentiation of mesenchymal stromal cells has been widely studied. However, a comparative characterization of ultrastructural changes during neural differentiation has not been performed. In this study, we conducted scanning electron microscopy and transmission electron microscopy analysis to show the morphological changes in mesenchymal stromal cells upon induction of neural differentiation. In addition, transmission electron microscopy results demonstrated ultrastructural differences between human cranial bone marrow mesenchymal stromal cells and iliac crest bone marrow mesenchymal stromal cells. We propose that enriched microvesicles in cranial bone marrow mesenchymal stromal cells may be responsible for the increased efficiency of neural differentiation.

Getting around the blood–brain barrier

Neuroimmunology The meninges comprise three membranes that surround and protect the central nervous system (CNS). Recent studies have noted the existence of myeloid cells resident there, but little is known about their ontogeny and function, and whether other meningeal immune cell populations have important roles remains unclear (see the Perspective by Nguyen and Kubes). Cugurra et al. found in mice that a large proportion of continuously replenished myeloid cells in the dura mater are not blood derived, but rather transit from cranial bone marrow through specialized channels. In models of CNS injury and neuroinflammation, the authors demonstrated that these myeloid cells have an immunoregulatory phenotype compared with their more inflammatory blood-derived counterparts. Similarly, Brioschi et al. show that the meninges host B cells that are also derived from skull bone marrow, mature locally, and likely acquire a tolerogenic phenotype. They further found that the brains of aging mice are infiltrated by a second population of age-associated B cells, which come from the periphery and may differentiate into autoantibody-secreting plasma cells after encountering CNS antigens. Together, these two studies may inform future treatment of neurological diseases. Science , abf7844, abf9277, this issue p. [eabf7844][1], p. [eabf9277][2]; see also abj8183, p. [396][3] [1]: /lookup/doi/10.1126/science.abf7844 [2]: /lookup/doi/10.1126/science.abf9277 [3]: /lookup/doi/10.1126/science.abj8183

Case Report of Aggressive T-Cell Large Granular Lymphocytic Leukemia

Large granular lymphocyte (LGL) leukemia is a spectrum of rare lymphoproliferative disorders. Two entities are reported: indolent T-cell LGL leukemia and aggressive NK cell leukemia. However, a review of the literature identified cases of aggressive T-cell LGL. Considering this unusual and rare clinical presentation, we are reporting a case of aggressive T-cell LGL leukemia.A 53-yo man presented in May 2014 with a one year history of constitutional symptoms, splenomegaly, mild lymphocytosis and a pancytopenia (hemoglobin 105 g/L, neutrophils 0,5 x 109 /L and platelets 80 x 109 /L). He had similar symptoms at the age of 24 that resolved without further investigation. Bone marrow evaluation revealed a massive infiltration by small to medium sized lymphocytes with irregular nucleus CD3 +, CD4 -, CD7 -, CD8 +, CD25 -, CD33 -, CD34 -, CD56 -, CD57 -, TCRαβ+. HTLV-1 serology was negative. His pancytopenia did not improve with 3 cycles of CHOP followed by 4 cycles of ESHAP. In January 2015, indolent T LGL was finally retained. The patient was observed up to July 2015 where methotrexate was begun because of frequent infections and symptomatic splenomegaly. A splenectomy was performed in January 2016 due to a toxicity to methotrexate and persistent symptoms from splenomegaly. Pathology report showed a splenic and lymph node infiltration by mature T CD8+ lymphocytes supporting the T LGL diagnosis. Post splenectomy, cytopenia improved and progressed in June 2016 with a lymphocytosis (82 x 109/L), new lung infiltrates and acute renal insufficiency. The lung biopsy revealed an infiltration by the T-cell LGL and renal imaging suggested infiltration by this T-cell LGL as well. Based on the weak expression of CD20+ on the splenic pathology, rituximab was attempted in August 2016. The patient rapidly progressed fatally with systemic involvement of T-cell LGL (skin, lungs, liver, kidney, facial cranial nerves, conus medullaris and bone marrow).This case therefore depicts a very aggressive case of T-cell LGL with an atypical clinical presentation. In contrast to the indolent variant and as seen in the few similar cases retrieved in literature, the clinical presentation of the aggressive T-cell LGL leukemia is characterized by constitutional symptoms, rapidly progressive hepatosplenomegaly, cytopenia with/without organic infiltration and an important resistance to treatment. Moreover, concerning the pathological findings, the medullary involvement of our patient was massive without real images of intra-sinusal lymphocytosis and the T-cell of this T-cell LGL were atypical because of their small-medium size with slightly irregular nuclei and the lack of expression of CD56 and CD57. However, the few studies on aggressive T-cell LGL leukemia retrieved similar findings. Even though there is no consensus on the optimal therapeutic management of this disease, we believe that the treatments given to our patient were consistent with literature and did not add an additional mortality risk.To conclude, LGL cell leukemia represent a spectrum of indolent and aggressive diseases, whereby an indolent form can evolve into an aggressive form. Aggressive T-cell LGL leukemia are characterized by a multisystem disease, an atypical immunophenotype (CD56-, CD57-) and are associated with an uncertainty regarding therapeutics. [Display omitted] DisclosuresFleury:Gilead: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Janssen: Consultancy, Honoraria.

Heterogeneity of meningeal B cells reveals a lymphopoietic niche at the CNS borders

The meninges contain adaptive immune cells that provide immunosurveillance of the CNS. These cells are thought to derive from the systemic circulation. Through single-cell analyses, confocal imaging, bone marrow chimeras, and parabiosis experiments, we show that meningeal B cells derive locally from the calvaria, which harbors a bone marrow niche for hematopoiesis. B cells reach the meninges from the calvaria through specialized vascular connections. This calvarial-meningeal path of B cell development may provide the CNS with a constant supply of B cells educated by CNS antigens. Conversely, we show that a subset of antigen-experienced B cells that populate the meninges in aging mice are blood-borne. These results identify a private source for meningeal B cells. which may help maintain immune privilege within the CNS.

Skull and vertebral bone marrow are myeloid cell reservoirs for the meninges and CNS parenchyma.

The meninges are a membranous structure enveloping the central nervous system (CNS) that host a rich repertoire of immune cells mediating CNS immune surveillance. Here, we report that the mouse meninges contain a pool of monocytes and neutrophils supplied not from the blood but by adjacent skull and vertebral bone marrow. Under pathological conditions, including spinal cord injury and neuroinflammation, CNS-infiltrating myeloid cells can originate from brain borders and display transcriptional signatures distinct from their blood-derived counterparts. Thus, CNS borders are populated by myeloid cells from adjacent bone marrow niches, strategically placed to supply innate immune cells under homeostatic and pathological conditions. These findings call for a reinterpretation of immune-cell infiltration into the CNS during injury and autoimmunity and may inform future therapeutic approaches that harness meningeal immune cells.

Microvascular Pachymeningeal Lymphatic Structures: Association with Blood Vessels and Cranial Bones

The role of cranial dura mater microvascular networks, as means for maintaining brain fluid movement and balance, and as the source of significant initiators and/or contributors to neurological disorders, has been underappreciated until recently. These networks consist of both blood and lymphatic vessels. The goal of this study was to uncover microvascular pachymeningeal lymphatic structures that are not associated with venous sinuses and investigate their interrelationship with the blood microvascular networks and cranial bones. Using markers specific for blood and lymphatic endothelia, we demonstrate the existence of the complex non‐sinus‐associated lymphatic microvasculature. We show the interrelationship and possible connections between lymphatic vessels and dural blood vessels. Furthermore, we unveil vascular connections between dural microvascular networks and cranial bone marrow sinusoids. Our novel findings reveal the presence of lymphatic‐like structures that exist on their own and/or in close proximity to microvessels. Of particular interest are sub‐sets of vascular complexes with dual (lymphatic and blood) vessel identity representing a unique microenvironment within the cranial dura. The close association of the systemic blood circulation and meningeal lymphatics achieved in these complexes could facilitate fluid exchange between the two compartments and constitute an alternative route for CSF drainage.Support or Funding InformationThis work was supported in parts by the NIH National Institute of Neurological Disorders and Stroke (R01NS110915), the NIH National Cancer Institute (R01 CA160461), and the U.S. Army Research Laboratory project W911NF‐18‐2‐0285.

3D printing of hydroxyapatite/tricalcium phosphate scaffold with hierarchical porous structure for bone regeneration

Three-dimensional (3D)-printed scaffolds have attracted considerable attention in recent years as they provide a suitable environment for bone cell tissue regeneration and can be customized in shape. Among many other challenges, the material composition and geometric structure have major impacts on the performance of scaffolds. Hydroxyapatite and tricalcium phosphate (HA/TCP), as the major constituents of natural bone and teeth, possess attractive biological properties and are widely used in bone scaffold fabrication. Many fabrication methods have been investigated in attempts to achieve HA/TCP scaffolds with microporous structure enabling cell growth and nutrient transport. However, current 3D printing methods can only achieve the fabrication of HA/TCP scaffolds with certain range of microporous structure. To overcome this challenge, we developed a slurry-based microscale mask image projection stereolithography, allowing us to form a HA/TCP-based photocurable suspension with complex geometry including biomimetic features and hierarchical porosity. Here, the curing performance and physical properties of the HA/TCP suspension were investigated, and a circular movement process for the fabrication of highly viscous HA/TCP suspension was developed. Based on these investigations, the scaffold composition was optimized. We determined that a 30 wt% HA/TCP scaffold with biomimetic hierarchical structure exhibited superior mechanical properties and porosity. Cell proliferation was investigated in vitro, and the surgery was conducted in a nude mouse in vivo model of long bone with cranial neural crest cells and bone marrow mesenchymal stem cells. The results showed our 3D-printed HA/TCP scaffold with biomimetic hierarchical structure is biocompatible and has sufficient mechanical strength for surgery.

Comparison of phenotypic markers and neural differentiation potential of human bone marrow stromal cells from the cranial bone and iliac crest.

Cellular therapies represent a new frontier in the treatment of neurological diseases. Accumulating evidence from preclinical studies of animal models suggests that mesenchymal stromal cells (MSCs), also known as mesenchymal stem cells, are an effective therapy for neurological diseases. In this study, we established human MSC lines from both cranial bone marrow (cBMMSCs) and iliac crest bone marrow (iBMMSCs) from the same donors and found that cBMMSCs show higher expression of neural crest-associated genes than iBMMSCs. Moreover, as observed in both mRNA and protein assays, neurogenic-induced cells from cBMMSCs expressed significantly higher levels of neural markers, such as NESTIN, SLUG, SOX9, and TWIST, than those from iBMMSCs. Thus, cBMMSCs showed a greater tendency than iBMMSCs to differentiate into neuron-like cells.

Sclerosing bone dysplasias with hallmarks of dysosteosclerosis in four patients carrying mutations in SLC29A3 and TCIRG1.

The osteopetroses and related sclerosing bone dysplasias can have a broad range of manifestations. Especially in the milder forms, sandwich vertebrae are an easily recognizable and reliable radiological hallmark. We report on four patients from three families presenting with sandwich vertebrae and platyspondyly. The long bone phenotypes were discordant with one patient showing modeling defects and patchy osteosclerosis, while the second displayed only metaphyseal sclerotic bands, and the third and fourth had extreme metaphyseal flaring with uniform osteosclerosis. Two of the four patients had experienced pathological fractures, two had developmental delay, but none showed cranial nerve damage, hepatosplenomegaly, or bone marrow failure. According to these clinical features the diagnoses ranged between intermediate autosomal recessive osteopetrosis and dysosteosclerosis. After exclusion of mutations in CLCN7 we performed gene panel and exome sequencing. Two novel mutations in SLC29A3 were found in the first two patients. In the third family a TCIRG1 C-terminal frameshift mutation in combination with a mutation at position +4 in intron 2 were detected. Our study adds two cases to the small group of individuals with SLC29A3 mutations diagnosed with dysosteosclerosis, and expands the phenotypic variability. The finding that intermediate autosomal recessive osteopetrosis due to TCIRG1 splice site mutations can also present with platyspondyly further increases the molecular heterogeneity of dysosteosclerosis-like sclerosing bone dysplasias.

Literature Review of All Cases of Aggressive T-Cell Large Granular Lymphocytic Leukemia Cases and Report of an Additional Case

Large granular lymphocyte (LGL) leukemia is a spectrum of rare lymphoproliferative disorders, classified into T-cell LGL leukemia, chronic lymphoproliferative disorder of NK-cells and aggressive NK-cell leukemia; chronic NK-cell leukemia is a provisional diagnosis.However, we identified fourteen cases of aggressive T-LGL leukemia retrieved in the literature. Considering this unusual and rare clinical presentation, we are reporting a literature review and presenting an additional case.Leukemic cells of T-LGL leukemia have a characteristic phenotype (CD3+CD8+CD16+CD57+) and show clonal TCR gene rearrangement, while leukemic cells of aggressive NK cell leukemia show a distinguishable phenotype (CD3-CD4-CD8-CD16+CD56+CD57-) and are EBV-related. In contrast with the aggressive NK cell leukemia, the chronic lymphoproliferative disorder of T-cell is not EBV-associated and has a distinguishable immunophenotype (CD16+CD56−CD57+). While T-LGL leukemia and chronic lymphoproliferative disorder of NK-cells have a more chronic disease (years), mainly reported with autoimmune disease (rheumatoid arthritis), numerous infections due to neutropenia and a mild-to-moderate splenomegaly, aggressive NK-cell leukemia is characterized by systemic manifestations and a disseminated disease after a few weeks of presentation despite treatment instauration.In contrast to the T-LGL leukemia, aggressive T-LGL leukemia has a clinical presentation similar to the aggressive NK-cell leukemia, characterized by constitutional symptoms, rapidly progressive hepatosplenomegaly, cytopenia and organ infiltration.The atypical clinical presentation and pathological findings of the aggressive T-LGL leukemia explain the diagnostic challenge of this entity for clinicians. In fact, cases of aggressive T- LGL leukemia retrieved atypical size, irregular nuclei and atypical immunophenotype. Some cases had features similar to those described for patients with NK-cell leukemia (CD56+CD57-) while others did not present neither NK nor T-cell classical immunophenotype (CD56-57-).Facing the heterogeneity of aggressive LGL leukemia, the rapidly evolutive disease (multi-organic infiltration) and the absence of randomized trials on large numbers of patients, no consensus on the treatment approach exists. (Table 1)Our patient presented, at the age of 24 yo, with transitory and autonomous resolution of hepatosplenomegaly and pancytopenia. Almost 30 years later, the patient developed a similar and persistent episode, which lead to a diagnosis of aggressive T-cell LGL leukemia. Was this first episode the early and indolent presentation of his T- LGL leukemia or was it only related to an indolent and transitory etiology? Considering the clinical evolution of previously reported case and of our patient, LGL leukemia tends to evolve in many ways; resolution, indolent and chronic or aggressive evolution and transformation into a lymphoma.As the cases retrieved in literature, the diagnosis of our patient was complicated by atypical clinical presentation and unusual pathological findings; massive medullary involvement without real images of intra-sinusal lymphocytosis and atypical T- LGL based on their small-medium size with slightly irregular nuclei and the lack of expression of CD56/CD57.Facing the heterogeneity of treatments attempted for aggressive T-LGL leukemia and their unpredictable response, we believe that the treatments given to our patient were consistent with the current literature and did not add an additional mortality risk (3 cycles of CHOP, 4 cycles of ESHAP, methotrexate, splenectomy).As reported in literature, even though our patient was treated with varying regimens, his disease rapidly evolved into a multi-organic infiltration (skin, lungs, liver, kidney, facial cranial nerves, conus medullaris and bone marrow involvement)Large granular lymphocyte (LGL) leukemia represent a spectrum of indolent and aggressive diseases, whereby an indolent form can evolve into an aggressive form. Aggressive T-cell LGL leukemia are characterized by a multisystem disease, an atypical immunophenotype (CD56-CD57- or CD56+CD57-) and are associated with an uncertainty regarding therapeutics.Our case report of an aggressive T-cell LGL leukemia adds to the few available studies on the subject. DisclosuresPavic:Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.