Pathology of macrophage activation syndrome in humanized NSGS mice.

"Humanized" immunodeficient mice generated via the transplantation of CD34+ human hematopoietic stem cells (hHSC) are an important preclinical model system. The triple transgenic NOD.Cg-PrkdcscidIl2rgtm1Wjl Tg(CMV-IL3,CSF2,KITLG)1Eav/MloySzJ (NSGS) mouse line is increasingly used as recipient for CD34+ hHSC engraftment. NSGS mice combine the features of the highly immunodeficient NSG mice with transgenic expression of the human myeloid stimulatory cytokines GM-CSF, IL-3, and Kit ligand. While generating humanized NSGS (huNSGS) mice from two independent cohorts, we encountered a fatal macrophage activation syndrome (MAS)-like phenotype resulting from the transplantation of CD34+ hHSC. huNSGS mice exhibiting this phenotype declined clinically starting at approximately 10 weeks following CD34+ hHSC engraftment, with all mice requiring euthanasia by 16 weeks. Gross changes comprised small, irregular liver, splenomegaly, cardiomegaly, and generalized pallor. Hematological abnormalities included severe thrombocytopenia and anemia. Pathologically, huNSGS spontaneously developed a disseminated histiocytosis with infiltrates of activated macrophages and hemophagocytosis predominantly affecting the liver, spleen, bone marrow, and pancreas. The infiltrates were chimeric with a mixture of human and mouse macrophages. Immunohistochemistry suggested activation of the inflammasome in both human and murine macrophages. Active Epstein-Barr virus infection was not a feature. Although the affected mice exhibited robust chimerism of the spleen and bone marrow, the phenotype often developed in the face of low chimerism of the peripheral blood. Given the high penetrance and early lethality associated with the MAS-like phenotype here described, we urge caution when considering the use of huNSGS mice for the development of long-term studies.

Autoinflammation in addition to combined immunodeficiency: SLC29A3 gene defect.

INTRODUCTION: H Syndrome is an autosomal recessive (AR) disease caused by defects in SLCA29A3 gene. This gene encodes the equilibrative nucleoside transporter, the protein which is highly expressed in spleen, lymph node and bone marrow. Autoinflammation and autoimmunity accompanies H Syndrome (HS). AIM: The aim was to further elucidate the mechanisms of disease by molecular studies in a patient with SLC29A3 gene defect. PATIENT AND METHODS: Mitochondrial dysfunction, lysosomal integrity, cytokine response in response to stimulation with different pattern recognition receptor ligands, and circulating cell-free mitochondrial-DNA(ccf-mtDNA) level in plasma were analyzed compared to controls to understand the cellular triggers of autoinflammation. RNA sequencing (RS) analyses were also performed in monocytes before/after culture with lipopolysaccharide. RESULTS: Patient had progressive destructive arthropathy in addition to clinical findings due to combined immunodeficiency. Pure red cell aplasia (PRCA), vitiligo, diabetes, multiple autoantibody positivity, lymphopenia, increased acute phase reactants were present. Recent thymic emigrants (RTE), naïve T cells were decreased, effector memory CD4 + T cells, nonclassical inflammatory monocytes were increased. Patient's peripheral blood mononuclear cells secreted more IL-1ß and IL-6, showed lysosomal disruption and significant mitochondrial dysfunction compared to healthy controls. Plasma ccf-mtDNA level was significantly elevated compared to age-matched controls (p < 0.05). RNA sequencing studies revealed decreased expression of NLR Family Caspase Recrument-Domain Containing 4(NLRC4), 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4(PFKFB4), serine dehydratase(SDS), heparan sulfate(Glucosamine) 3-O-sulfotransferase 1(HS3ST1), neutral cholesterol ester hydrolase 1 (NCEH1), and interleukin-8 (IL-8) in patient's monocytes compared to controls. Longstanding PRCA, which is possibly autoimmune, resolved after initiating monthly intravenous immunoglobulins (IVIG) and low dose steroids to the patient. CONCLUSION: Although autoinflammation and autoimmunity are reported in HS, by functional analyses we here show in the present patient that over-active inflammasome pathway in HS might be related with mitochondrial and lysosomal dysfunction. Increased plasma ccf-mtDNA may be used as a biomarker of inflammasomopathy in HS. HS should be included in the classification of primary immunodeficiency diseases.

Complement receptor-associated CD163+/CD18+/CD11c+/CD206-/CD209- expression profile in chronic histiocytic intervillositis of the placenta.

INTRODUCTION: Chronic histiocytic intervillositis of unknown etiology (CIUE) is a non-infectious, most probably immunologic placenta lesion. CIUE is associated with recurrent miscarriage, intrauterine growth restriction and stillbirth. Among the pathologic-anatomic defined placental lesions this entity displays the highest risk of recurrence in following pregnancies (about 67-100%). The histiocytic cells accumulate in the placental blood space but do not infiltrate into the villi or decidua. Sparsely known is the expression profile of these intervillous cells regarding histiocytic markers. METHODS: We analysed 5-22 markers by immunohistochemistry in a total of 41 placenta samples and evaluated decidual, villous and intervillous histiocytic cells. RESULTS: In CIUE, intervillous CD163+ histiocytes over-express CD11c/CD18 and down-regulate CD206/CD209, while CD163+ decidual and Hofbauer cells show low CD11c/CD18 and higher CD206/CD209 protein expressions. DISCUSSION: CD163 expression indicates a M2-like polarisation. CD11c and CD18 form the complement receptor 4 which could be related to a complement mediated trigger for aberrant cell accumulation in CIUE.

Imaging features of immune-mediated genitourinary disease.

PURPOSE: Imaging features of immune-mediated genitourinary diseases often overlap, and the same disease may manifest in different ways, so understanding imaging findings in the context of the patient's entire clinical picture is important in providing the correct diagnosis. METHODS: In this article, diseases mediated by the immune system which affect the genitourinary system are reviewed. Examples of immune-mediated genitourinary disease including IgG4-related disease, post-transplant lymphoproliferative disorder, immunodeficiency-associated lymphoproliferative disorder due to immunosuppressive and immunomodulatory medications, lymphoma, leukemia, myeloma, amyloidosis, and histiocytosis. RESULTS: Clinical and imaging features will be presented which may help narrow the differential diagnosis for each disease. CONCLUSION: Recognition of immune-related genitourinary disease is important for appropriate medical management as they may mimic other diseases both by imaging and clinical presentation.

Crystal-storing Histiocytosis in the Stomach: A Clue to Subtle Hematolymphoid Malignancies.

Crystal-storing histiocytosis (CSH) is an under-recognized entity with a striking association with lymphoproliferative disorders. To study the typical morphologic features of gastric CSH, all lymphomas diagnosed on in-house gastric specimens at The Ohio State University between January 1, 2008 and January 1, 2017 were retrieved. This search yielded 66 specimens from 51 unique patients. All cases were reviewed with CSH identified in 7 stomach biopsies from 4 patients (2 men:2 women; average age, 69 y; range, 56 to 82 y). Endoscopic findings were all abnormal: diffuse nodularity and white discoloration (n=1), patchy nodularity (n=1), and malignant-appearing fundic mass with lymphadenopathy (n=2). We report the typical gastric CSH lesion displays full-thickness expansion of the lamina propria by a lymphohistiocytic infiltrate that distorts the usual gastric glandular architecture. On high power, all cases were defined by the presence of macrophages with abundant eosinophilic cytoplasm containing nonrefractile, nonpolarizable fibrillary cytoplasmic inclusions. Three of the 4 patients had a kappa-restricted lymphoma; the 1 patient with a lambda-restricted lymphoma had the fewest macrophages. Follow-up data were available up to 228 weeks. All 4 patients had persistent/recurrent lymphoma, and 2 patients died of lymphoma-related complications. None of the CSH cases were prospectively recognized as CSH, and 1 case was initially misdiagnosed as a xanthoma. In summary, CSH is an under-recognized lesion historically associated with lymphoproliferative disorders and we found associated with a high mortality in this small series. Since CSH can be so florid as to obscure the concomitant lymphoma, awareness is crucial for accurate diagnosis.

Autoinflammatory Diseases in Pediatric Dermatology-Part 2: Histiocytic, Macrophage Activation, and Vasculitis Syndromes. / Enfermedades autoinflamatorias en dermatología pediátrica. Parte 2: síndromes histiocítico-macrofágicos y síndromes vasculopáticos.

The discovery of new autoinflammatory syndromes and novel mutations has advanced at breakneck speed in recent years. Part 2 of this review focuses on vasculitis syndromes and the group of histiocytic and macrophage activation syndromes. We also include a table showing the mutations associated with these autoinflammatory syndromes and treatment alternatives.

Localized pulmonary crystal-storing histiocytosis complicating pulmonary mucosa-associated lymphoid tissue lymphoma presenting with multiple mass lesions.

Crystal-storing histiocytosis (CSH) is an uncommon finding in lymphoplasmacytic disorders that presents histiocytes with abnormal intralysosomal accumulations of immunoglobulin light chains as crystals of unknown etiology. A 38-year-old woman with antiphospholipid syndrome had a surgical lung biopsy because of multiple lung mass lesions. In a right middle lobe lesion, lymphoplasmacytic cells had a monocytoid appearance, destructive lymphoepithelial lesions, and positive immunoglobulin heavy chain (IGH) gene rearrangements. A right upper lobe lesion manifested proliferating rounded histiocytes with abundant, deeply eosinophilic cytoplasm and negative IGH gene rearrangements. Electron microscopy and mass spectrometry revealed a case of pulmonary CSH: abnormal proliferation of the immunoglobulin κ chain of a variable region that may be crystallized within plasma cells and histiocytes. We report a rare case of localized pulmonary CSH complicating pulmonary mucosa-associated lymphoid tissue lymphoma with multiple mass lesions. We demonstrate advances in the understanding of the pathogenesis of CSH by various analyses of these lesions.

Cutaneous S100-negative, CD1a-positive histiocytosis successfully treated with combination therapy of oral methotrexate and corticosteroid.

S100-negative, CD1a-positive histiocytosis is a rare histiocytic disorder characterized by proliferation of histiocytic cells possessing a phenotype of epidermal Langerhans cells except for the lack of S100 expression and Birbeck granules. We report the case of a Japanese man suffering from S100-negative, CD1a-positive histiocytosis. The patient showed numerous smooth erythematous 5-10-mm papules/nodules on most of his body. The key histopathological feature was the presence of dermal infiltrates of non-epidermotropic S100-negative CD1a-positive mononuclear cells. No systemic involvement was detected. Initially bath-psoralen plus ultraviolet A therapy was effective, but the lesions became recalcitrant to this treatment. Methylprednisolone pulse therapy followed by low-dose methotrexate (up to 30 mg/week) in combination with prednisolone (15 mg/day) effectively controlled the skin lesions.

Incidental simultaneous finding of intravascular histiocytosis and reactive angioendotheliomatosis: a case report.

Reactive angioendotheliomatosis (RAE) is a rare cutaneous vascular disorder characterized by intravascular hyperplasia of endothelial cells, sometimes with a vascular proliferation. Intravascular histiocytosis (IH) is a similar vascular disorder characterized by the presence of dilated vessels containing aggregates of mononuclear histiocytes (macrophages) within their lumina. Although their pathogenesis remains uncertain, there has been speculation about the possible relationship between IH and RAE. We report a case of coexistence of RAE and IH in a patient who underwent a wide reexcision of a metastatic malignant melanoma. The excision specimen did not show any residual melanoma but exhibited an intravascular collection of CD-68-positive histiocytes admixed with CD-31-positive endothelial cells and fibrin surrounded by D2-40-positive vascular wall. The presence of intravascular cells initially raised concern of intravascular invasion by melanoma. As there was no clinical lesion and immunohistochemical stains for melanocytic makers were negative, we interpret this as an incidental finding. Knowledge of this benign vascular disorder is important because the histologic changes may be mistaken for intravascular invasion of a malignant neoplasm.

Indeterminate cell histiocytosis that presented clinically as benign cephalic histiocytosis.

Indeterminate cell histiocytosis (ICH) is a rare, heterogeneous disorder that is characterized by immunophenotypic features of both Langerhans cell histiocytosis (LCH) and non-LCH. We describe a 12-month-old boy with a four-month history of asymptomatic, small, pink-tan papules on his face. Histopathologic evaluation showed a superficial, dermal infiltrate of histiocytes that was positive for S100, CD1a, CD68, and Factor XIIIa. To our knowledge, this represents the first report of the clinical presentation of benign cephalic histiocytosis with immunohistochemical findings of ICH. We review the classification of histiocytic disorders and the clinical and immunohistochemical features of both ICH and benign cephalic histiocytosis.

Primary and secondary intralymphatic histiocytosis.

BACKGROUND: Intralymphatic histiocytosis (IH) is a rare condition often associated with systemic disease. A benign condition, clinical presentations can vary greatly and its cause is largely unknown. Histologically, there are macrophages within distended lymphatic vessels, although this can be an incidental finding or the primary abnormality. OBJECTIVE: We present a series of 7 cases of IH with and without disease associations, and a review of the literature. We propose IH as either primary (without associated conditions) or secondary (associated with systemic disease). METHODS: This was a retrospective collection of patients whose skin biopsy specimens revealed intralymphatic collections of histiocytes. We reviewed their clinical presentation, disease associations, and staining of slides with CD68 in all cases, D2-40 in 5 cases, and HLA-DR in 4 cases. RESULTS: Clinical features were highly variable, and not all cases were associated with systemic disease. One case had admixed reactive angioendotheliomatosis. All 4 cases stained for HLA-DR showed strong expression by the intralymphatic macrophages. LIMITATIONS: Retrospective analysis and limited numbers are limitations. CONCLUSION: IH is not always associated with systemic disease although macrophage activation nevertheless implies immune activation.

Transgenic expression of GM-CSF in T cells causes disseminated histiocytosis.

Recent studies highlight surprising roles for granulocyte-macrophage colony-stimulating factor (GM-CSF) production by T cells. T-cell-derived GM-CSF is required for the differentiation of monocyte-derived inflammatory dendritic cells during inflammation and for the pathogenicity of IL-17 producing T helper cells in autoimmunity. To gain further insight into these findings, we engineered in vivo overexpression of GM-CSF specifically in T cells, under the control of the Lck promoter. Lck-GM-CSF transgenic mice displayed a dramatic phenotype, characterized by splenomegaly, lymphadenopathy, thymic atrophy, and multiple abnormalities in blood cell populations. Thymocyte differentiation was severely affected, and there was a dramatic increase in regulatory T cells in the thymus and peripheral lymphoid organs. Lck-GM-CSF transgenic mice developed a disseminated histiocytosis and had increased circulating IL-17 producing T helper cells-related cytokines. The pathological characteristics in Lck-GM-CSF transgenic mice resemble those of histiocytic human diseases, such as Langerhans cell histiocytosis. The etiology of many histiocytic disorders is unknown, but our findings suggest that over-production of GM-CSF by T cells could be a pathogenic factor and raise the possibility that GM-CSF may represent a novel therapeutic target.

Pathological consequence of misguided dendritic cell differentiation in histiocytic diseases.

Histiocytic disorders represent a group of complex pathologies characterized by the accumulation of histiocytes, an old term for tissue-resident macrophages and dendritic cells. Langerhans cell histiocytosis is the most frequent of histiocytosis in humans and has been thought to arise from the abnormal accumulation of epidermal dendritic cells called Langerhans cells. In this chapter, we discuss the origin and differentiation of Langerhans cells and dendritic cells and present accumulated evidence that suggests that Langerhans cell histiocytosis does not result from abnormal Langerhans cell homeostasis but rather is a consequence of misguided differentiation programs of myeloid dendritic cell precursors. We propose reclassification of Langerhans cell histiocytosis, juvenile xanthogranuloma, and Erdheim-Chester disease as inflammatory myeloid neoplasias.

Clonal cytophagic histiocytic panniculitis in children may be cured by cyclosporine A.

Cytophagic histiocytic panniculitis (CHP) is a rare panniculitis in childhood, associated either with nonmalignant conditions or with subcutaneous panniculitis-like T-cell lymphoma (SPTCL), and often also associated with macrophage activation syndrome (MAS). Discriminating between these 2 conditions is therapeutically important because nonmalignant CHP often improves under cyclosporine and prednisone, whereas most cases of SPLT may be best treated with more aggressive therapy. We report the cases of a 6-month-old boy and a 16-month-old girl who, after viral infection, developed multiple infiltrating skin nodules on the limbs and face, associated with MAS. Histopathologic findings for skin biopsy specimens revealed CHP associated with heavily cellular lobular panniculitis. Hemophagocytosis and immunohistochemical staining features were consistent with typical characteristics of in situ MAS in adipose tissue: the lymphocytes were mostly TCD8+ cells with an activated phenotype (human leukocyte antigen (HLA) -DR+) and expressed interferon-γ; CD68+ macrophages expressed tumor necrosis factor-α and interleukin-6. A monoclonal rearrangement of the T-cell receptor γ gene was present in skin tissue but not in peripheral blood or bone marrow lymphocytes. Cyclosporine A treatment resulted in the complete remission of cutaneous and systemic manifestations in both patients for 66 and 29 months, respectively. This report suggests that the diagnosis of a reactive T-cell lymphoproliferation should be the treatment of choice in young children with severe CHP, even if there is a SPTCL-like aspect with an in situ T-cell clonality. It also suggests that CSA is the optimal treatment of this condition and postulates the possible pathologic process underlying this efficacy.

Pigmentary hypertrichosis and non-autoimmune insulin-dependent diabetes mellitus (PHID) syndrome is associated with severe chronic inflammation and cardiomyopathy, and represents a new monogenic autoinflammatory syndrome.

Mutations in SLC29A3 lead to pigmentary hypertrichosis and non-autoimmune insulin-dependent diabetes mellitus (PHID) and H syndromes, familial Rosai-Dorfman disease, and histiocytosis-lymphadenopathy plus syndrome. We report a new association of PHID syndrome with severe systemic inflammation, scleroderma-like changes, and cardiomyopathy. A 12-year-old girl with PHID syndrome presented with shortness of breath, hepatosplenomegaly, and raised erythrocyte sedimentation rate and C-reactive protein. An echocardiogram showed biventricular myocardial hypertrophy, and cardiac magnetic resonance imaging showed circumferential late gadolinium enhancement of the myocardium. No systemic amyloid deposits were observed on a whole-body serum amyloid P scintigraphy scan. Abdominal ultrasound revealed intra-abdominal fat surrounding the solid organs, suggesting a possibility of evolving lipodystrophy with visceral adiposity. PHID syndrome is a novel monogenic autoinflammatory syndrome (AIS) associated with severe elevation of serum amyloid. Lipodystrophy, cutaneous sclerodermatous changes, and cardiomyopathy were also present in this case. In contrast to other AIS, blockade of interleukin-1 and tumor necrosis-α was ineffective.

Self-regressing S100-negative CD1a-positive cutaneous histiocytosis.

In the skin, the antigen-presenting cells are mainly represented by Langerhans cells, indeterminate cells, and interstitial dendritic cells, which show distinctive immunophenotype and/or ultrastructure. We report a case of a cutaneous-limited self-regressing histiocytosis with a peculiar immunohistochemical profile (CD1a-positive and S100 protein-negative) that is not observed in any of the known cutaneous antigen-presenting cell or nowadays recognized neoplasm. This lesion is probably related to indeterminate dendritic cell tumors, but very few cases with such immunoprofile have been reported up-to-date, and their exact nosologic position and outcome remain to be clarified.