Bevacizumab-induced immune thrombocytopenia in an ovarian cancer patient with mixed connective tissue disease: case report and literature review.

Drug-induced immune thrombocytopenia is an adverse reaction marked by accelerated destruction of blood platelets. In cancer therapy, thrombocytopenia has many other causes including bone marrow suppression induced by chemotherapeutic agents, infection, and progression of cancer; drug-induced thrombocytopenia can easily be misdiagnosed or overlooked. Here, we present a case of an ovarian cancer patient with a history of mixed connective tissue disease who underwent surgery followed by treatment with paclitaxel, cisplatin, and bevacizumab. The patient developed acute isolated thrombocytopenia after the sixth cycle. Serum antiplatelet antibody testing revealed antibodies against glycoprotein IIb. After we analyzed the whole therapeutic process of this patient, drug-induced immune thrombocytopenia was assumed, and bevacizumab was conjectured as the most probable drug. Thrombocytopenia was ultimately successfully managed using recombinant human thrombopoietin, prednisone, and recombinant human interleukin-11. We provide a summary of existing literature on immune thrombocytopenia induced by bevacizumab and discuss related mechanisms and triggers for drug-induced immune thrombocytopenia. The present case underscores the potential of bevacizumab to induce immune-mediated thrombocytopenia, emphasizing the need for heightened vigilance towards autoimmune diseases or an autoimmune-activated state as plausible triggers for rare drug-induced immune thrombocytopenia in cancer therapy.

Evolution of diagnostic criteria and new insights into clinical testing in mixed connective tissue disease; anti-survival motor neuron complex antibody as a novel marker of severity of the disease.

Mixed connective tissue disease (MCTD) is an autoimmune disorder characterized by a combination of clinical features from systemic lupus erythematosus, systemic sclerosis, and inflammatory muscle disease, along with the presence of positive anti-U1-ribonucleoprotein (U1-RNP) antibodies. The exact etiology of the disease remains unclear, but it is believed to involve vascular damage within the context of heightened autoimmune responses. Consequently, Raynaud's phenomenon and pulmonary arterial hypertension are observed in patients with MCTD. While specific biomarkers for MCTD have not yet been identified, the recent study of the utility of anti-survival motor neuron complex (SMN) antibodies in MCTD suggests a promising avenue for further research and the accumulation of additional evidence.

Anti-U1RNP antibodies are associated with a distinct clinical phenotype and a worse survival in patients with systemic sclerosis.

OBJECTIVES: To clarify the impact of anti-U1RNP antibodies on the clinical features and prognosis of patients with SSc. METHODS: We conducted a monocentric case-control, retrospective, longitudinal study. For each patient with SSc and anti-U1RNP antibodies (SSc-RNP+), one patient with mixed connective tissue disease (MCTD) and 2 SSc patients without anti-U1RNP antibodies (SSc-RNP-) were matched for age, sex, and date of inclusion. RESULTS: Sixty-four SSc-RNP+ patients were compared to 128 SSc-RNP- and 64 MCTD patients. Compared to SSc-RNP-, SSc-RNP+ patients were more often of Afro-Caribbean origin (31.3% vs. 11%, p < 0.01), and more often had an overlap syndrome than SSc-RNP- patients (53.1 % vs. 22.7%, p < 0.0001), overlapping with Sjögren's syndrome (n = 23, 35.9%) and/or systemic lupus erythematosus (n = 19, 29.7%). SSc-RNP+ patients were distinctly different from MCTD patients but less often had joint involvement (p < 0.01). SSc-RNP+ patients more frequently developed interstitial lung disease (ILD) (73.4% vs. 55.5% vs. 31.3%, p < 0.05), pulmonary fibrosis (PF) (60.9% vs. 37.5% vs. 10.9%, p < 0.0001), SSc associated myopathy (29.7% vs. 6.3% vs. 7.8%, p < 0.0001), and kidney involvement (10.9% vs. 2.3% vs. 1.6%, p < 0.05). Over a 200-month follow-up period, SSc-RNP+ patients had worse overall survival (p < 0.05), worse survival without PF occurrence (p < 0.01), ILD or PF progression (p < 0.01 and p < 0.0001). CONCLUSIONS: In SSc patients, anti-U1RNP antibodies are associated with a higher incidence of overlap syndrome, a distinct clinical phenotype, and poorer survival compared to SSc-RNP- and MCTD patients. Our study suggests that SSc-RNP+ patients should be separated from MCTD patients and may constitute an enriched population for progressive lung disease.

Antigen-driven autoantibody production in lungs of interstitial lung disease with autoimmune disease.

Interstitial lung disease (ILD) sometimes becomes a life-threatening complication of systemic autoimmune diseases; however, little is known about the immune response in lung lesions. We aimed to investigate humoural immunity in ILD associated with rheumatoid arthritis (RA), sjögren's syndrome (SjS), and mixed connective tissue disease (MCTD), using bronchoalveolar fluid (BALF) and serum samples from 15 patients with autoimmune disease associated-ILD. We first showed that BALF contained higher titers of disease-related autoantibodies than serum, suggesting the possibility of autoantibody production in lungs. Next, we produced 326 monoclonal antibodies from antibody-secreting cells in BALF, and the reactivity and their revertants, in which somatic hypermutations were reverted to germline, were analyzed. Among 123 antibodies from RA-ILD, 16 disease-related antibodies (anti-modified protein antibodies and rheumatoid factors) were identified, of which one antibody had both properties. The revertant antibodies changed their target modification in a complicated manner, suggesting that the antibodies were selected against various modifications in lungs. Among 146 antibodies from SjS-ILD and/or MCTD-ILD, seven anti-SSA/Ro60 antibodies and 15 anti-RNP antibodies were identified. Some of the anti-RNP antibodies recognized multiple RNP constituent proteins simultaneously, indicating that epitope spreading may progress in lungs. Our results revealed the existence of an active autoimmunity in the lungs of autoimmune disease associated-ILD.

Integrative Analysis Reveals a Molecular Stratification of Systemic Autoimmune Diseases.

OBJECTIVE: Clinical heterogeneity, a hallmark of systemic autoimmune diseases, impedes early diagnosis and effective treatment, issues that may be addressed if patients could be classified into groups defined by molecular pattern. This study was undertaken to identify molecular clusters for reclassifying systemic autoimmune diseases independently of clinical diagnosis. METHODS: Unsupervised clustering of integrated whole blood transcriptome and methylome cross-sectional data on 955 patients with 7 systemic autoimmune diseases and 267 healthy controls was undertaken. In addition, an inception cohort was prospectively followed up for 6 or 14 months to validate the results and analyze whether or not cluster assignment changed over time. RESULTS: Four clusters were identified and validated. Three were pathologic, representing "inflammatory," "lymphoid," and "interferon" patterns. Each included all diagnoses and was defined by genetic, clinical, serologic, and cellular features. A fourth cluster with no specific molecular pattern was associated with low disease activity and included healthy controls. A longitudinal and independent inception cohort showed a relapse-remission pattern, where patients remained in their pathologic cluster, moving only to the healthy one, thus showing that the molecular clusters remained stable over time and that single pathogenic molecular signatures characterized each individual patient. CONCLUSION: Patients with systemic autoimmune diseases can be jointly stratified into 3 stable disease clusters with specific molecular patterns differentiating different molecular disease mechanisms. These results have important implications for future clinical trials and the study of nonresponse to therapy, marking a paradigm shift in our view of systemic autoimmune diseases.

Membranous Nephropathy: Core Curriculum 2021.

The understanding and management of membranous nephropathy, a common cause of nephrotic syndrome that is more frequently encountered in adults than in children, has rapidly evolved over the past decade. Identification of target antigens has allowed for more precise molecular diagnoses, and the ability to monitor circulating autoantibodies has added a new vantage point in terms of disease monitoring and decisions about immunosuppression. Although immunosuppression with alkylating agents combined with corticosteroids, or with calcineurin inhibitor-based regimens, has been the historical mainstay of treatment, observational and now randomized controlled trials with the B-cell-depleting agent rituximab have moved this agent to the forefront of therapy for primary membranous nephropathy. In this Core Curriculum, we discuss the typical features of primary and secondary disease; highlight the target antigens such as the phospholipase A2 receptor, thrombospondin type 1 domain-containing 7A, neural epidermal growth factor-like 1, and semaphorin-3B; describe the relationship between the immunologic and clinical courses of disease; and review modern management with supportive care or immunosuppressive treatment based on these composite parameters.

Basophils and IgE contribute to mixed connective tissue disease development.

BACKGROUND: Mixed connective tissue disease (MCTD) is a rare and complex autoimmune disease that presents mixed features with other connective tissue diseases, such as systemic lupus erythematosus, systemic sclerosis, and myositis. It is characterized by high levels of anti-U1 small nuclear ribonucleoprotein 70k autoantibodies and a high incidence of life-threatening pulmonary involvement. The pathophysiology of MCTD is not well understood, and no specific treatment is yet available for the patients. Basophils and IgE play a role in the development of systemic lupus erythematosus and thus represent new therapeutic targets for systemic lupus erythematosus and other diseases involving basophils and IgE in their pathogenesis. OBJECTIVE: We sought to investigate the role of basophils and IgE in the pathophysiology of MCTD. METHODS: Basophil activation status and the presence of autoreactive IgE were assessed in peripheral blood of a cohort of patients with MCTD and in an MCTD-like mouse model. Basophil depletion and IgE-deficient animals were used to investigate the contribution of basophils and IgE in the lung pathology development of this mouse model. RESULTS: Patients with MCTD have a peripheral basopenia and activated blood basophils overexpressing C-C chemokine receptor 3. Autoreactive IgE raised against the main MCTD autoantigen U1 small nuclear ribonucleoprotein 70k were found in nearly 80% of the patients from the cohort. Basophil activation and IgE anti-U1 small nuclear ribonucleoprotein 70k were also observed in the MCTD-like mouse model along with basophil accumulation in lymph nodes and lungs. Basophil depletion dampened lung pathology, and IgE deficiency prevented its development. CONCLUSIONS: Basophils and IgE contribute to MCTD pathophysiology and represent new candidate therapeutic targets for patients with MCTD.

Salivary gland ultrasound in the diagnostic workup of juvenile Sjögren's syndrome and mixed connective tissue disease.

BACKGROUND: Juvenile Sjögren's Syndrome (jSS) is a rare phenomenon that may appear as primary jSS or associated with mixed connective tissue disease (MCTD) and other autoimmune diseases as secondary jSS. With currently no standard diagnostic procedures available, jSS in MCTD seems to be underdiagnosed. We intended to describe and identify similar distinct salivary gland ultrasound (SGUS) findings in a cohort of primary and secondary jSS patients, focusing on sicca like symptoms and glandular pain/swelling in the patients'history. METHODS: We present a single-center study with chart data collection. B-mode examinations of salivary glands were obtained with a linear high-frequency transducer and evaluated using the scoring-system of Hocevar. Inclusion criteria were: (i) primary or secondary jSS and/or (ii) diagnosis of MCTD and additionally (iii) any presence of sicca like symptoms or glandular pain/swelling. RESULTS: Twenty five patients with primary (pjSS) and secondary jSS (sjSS) were included in the study (n = 25, 21 female, 4 male), with a median age of 15.3 years at the time of first visit and a mean disease duration of 4.9 years. Pathologic SGUS findings were observed in 24 of 25 patients, with inhomogeneous parenchymal appearances with hypoechoic lesions present in 96% of patients. At least one submandibular gland was affected in 88.5% of the whole group, and all patients in the MCTD-group. Twenty of twenty five patients were scanned and scored on a second visit. Pre-malignancies or mucosa-associated lymphoid tissue (MALT) were detected in biopsies of three patients (Hocevar scoring of 40, 33, and 28). CONCLUSION: SGUS in patients with pjSS and sjSS is a helpful first-line tool to detect and score salivary gland involvement, in particular when keratoconjunctivitis sicca, xerostomia, or glandular swelling occurs. Juvenile MCTD patients have a significant risk of developing secondary jSS. We propose SGUS as a method in the diagnostic workup and screening for inflammatory changes. Further studies have to determine the predictive value of SGUS for follow up.

Anca negative pauci-immune crescentic glomerulonephritis and mixed connective tissue disease: a case study / Glomerulonefrite crescêntica pauci-imune ANCA-negativa e doença mista do tecido conjuntivo: relato de um caso

Abstract One of the most common causes of rapidly progressive glomerulonephritis (RPGN) is pauci-immune crescentic glomerulonephritis (CrGN). In the majority of cases, this condition has a positive serologic marker, the anti-neutrophil cytoplasmic antibodies (ANCAs), but in approximately 10% there are no circulating ANCAs, and this subgroup has been known as the ANCA-negative pauci-immune CrGN. RPGN can be associated with systemic diseases, but there are only few case reports describing the association with mixed connective tissue disease (MCTD). The authors report a case of ANCA-negative CrGN associated with a MCTD.

Resumo Uma das causas mais comuns da glomerulonefrite rapidamente progressiva (GNRP) é a glomerulonefrite crescêntica (GNC) pauci-imune. Na maioria dos casos, a patologia apresenta um marcador sorológico positivo, o anticorpo anticitoplasma de neutrófilos (ANCA), mas em cerca de 10% dos pacientes não há ANCAs circulantes, perfazendo um subgrupo da patologia conhecido como GNC pauci-imune ANCA-negativa. A GNRP pode estar associada a doenças sistêmicas, mas são poucos os relatos de caso que descrevem sua associação com doença mista do tecido conjuntivo (DMTC). O presente artigo relata um caso de GNC ANCA-negativa associada a DMTC.

Spectrum of paediatric rheumatic disorders at a tertiary hospital in Tanzania.

BACKGROUND: Paediatric rheumatic disorders are common in children and result in significant impairment in quality of life, morbidity and mortality. There is limited information on the burden of these disorders in lower income countries especially in sub-Saharan Africa. Few case reports have documented presence of paediatric rheumatic disorders in Tanzania. This study was conducted to determine the spectrum of rheumatic disorders among children at Muhimbili National Hospital (MNH). METHODS: This was a retrospective study conducted among children who were attended at MNH between January 2012 and August 2019. Paediatric patients seen in the out-patient clinics and those admitted in the wards were eligible. All patients with diagnosis of rheumatic disorders were identified from admission books and outpatient clinic logbooks, and later data were collected from their case notes and were recorded in clinical research forms. Collected information included age, sex, clinical features and laboratory tests results. RESULTS: A total of 52 children with mean age of 9.5 ± 4.3 years, 12 (40.4%) participants were aged above 10 years and 32 (61.5%) were females. Frequently reported clinical presentations were joint pain 44 (84.6%), joint swelling 34 (65.4%), fever 24 (46.2%) and skin rashes 21(40.4%). Juvenile idiopathic arthritis (JIA) was the predominant diagnosis reported in 28 (53.8%) participants followed by juvenile systemic lupus erythematosus 8 (15.4%), mixed connective tissue diseases 4 (7.7%) and juvenile dermatomyositis 4 (7.7%). Antinuclear antibody test was performed in 16 participants it was positive in 9 (56.2%). Nine participants were tested for anti-double stranded DNA test and 5 (55.6%) were positive for this test. C-reactive protein was tested in 46 participants out of which 32 (69.6%) had elevated levels. HIV was tested in 24 (46.2%) participants and results were negative. Thirty-five out of 52 (67.3%) participants had anaemia. Predominant drugs used for treatment of JIA include prednisolone and methotrexate. CONCLUSIONS: Paediatric rheumatic disorders are not uncommon in Tanzania-and were noted to affect more female children in this study. Predominant conditions included juvenile idiopathic arthritis (JIA), juvenile systemic lupus erythematosus (JSLE) and juvenile dermatomyositis (JDM).

Pulmonary infection due to Acrophialophora fusispora in a patient with underlying mixed connective tissue disease and chronic pulmonary aspergillosis: A case report and review of literature.

Acrophialophora fusispora is a soil-borne fungus rarely implicated in human infections. Here, we report a case of pulmonary infection due to A. fusispora in a 59-year-old male who presented with productive cough and gradually progressive dyspnoea for 20 days. He had a past history of pulmonary tuberculosis and was a known case of chronic obstructive pulmonary disease for past five years. He was diagnosed with mixed connective tissue disease and had been receiving oral azathioprine and prednisolone for three months. CECT thorax revealed an aspergilloma and serum Aspergillus fumigatus-specific IgG levels were raised, suggestive of chronic pulmonary aspergillosis. He was also tested positive for influenza A (H1N1) and received treatment with oral oseltamivir without any clinical benefit. Culture of sputum and bronchoalveolar lavage fluid showed growth of a fungus which was identified as Acrophialophora fusispora based on characteristic microscopic morphology and internal transcribed spacer sequencing of the ribosomal DNA. Antifungal susceptibility testing for six antifungal drugs showed itraconazole to have the most potent in vitro activity (MIC=0.25µg/mL) against A. fusispora in comparison to the other drugs tested. Treatment with itraconazole capsule 200mg twice daily was initiated and favourable clinical response was observed after 10 days of therapy. Follow-up visit after three months showed marked clinical and radiological improvement. A. fusispora is an emerging opportunistic fungus capable of causing invasive infections in immunocompromised hosts. Lack of knowledge about this fungus and confusion with morphologically similar opportunistic fungi have led to its misidentification and hence its prevalence remains largely underestimated. Accurate identification is crucial as it can help initiate early effective antifungal therapy and improve patient outcomes. To our knowledge, this is the first case of pulmonary infection due to A. fusispora reported from India.

Epigenome-Wide Comparative Study Reveals Key Differences Between Mixed Connective Tissue Disease and Related Systemic Autoimmune Diseases.

Mixed Connective Tissue Disease (MCTD) is a rare complex systemic autoimmune disease (SAD) characterized by the presence of increased levels of anti-U1 ribonucleoprotein autoantibodies and signs and symptoms that resemble other SADs such as systemic sclerosis (SSc), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE). Due to its low prevalence, this disease has been very poorly studied at the molecular level. We performed for the first time an epigenome-wide association study interrogating DNA methylation data obtained with the Infinium MethylationEPIC array from whole blood samples in 31 patients diagnosed with MCTD and 255 healthy subjects. We observed a pervasive hypomethylation involving 170 genes enriched for immune-related function such as those involved in type I interferon signaling pathways or in negative regulation of viral genome replication. We mostly identified epigenetic signals at genes previously implicated in other SADs, for example MX1, PARP9, DDX60, or IFI44L, for which we also observed that MCTD patients exhibit higher DNA methylation variability compared with controls, suggesting that these sites might be involved in plastic immune responses that are relevant to the disease. Through methylation quantitative trait locus (meQTL) analysis we identified widespread local genetic effects influencing DNA methylation variability at MCTD-associated sites. Interestingly, for IRF7, IFI44 genes, and the HLA region we have evidence that they could be exerting a genetic risk on MCTD mediated through DNA methylation changes. Comparison of MCTD-associated epigenome with patients diagnosed with SLE, or Sjögren's Syndrome, reveals a common interferon-related epigenetic signature, however we find substantial epigenetic differences when compared with patients diagnosed with rheumatoid arthritis and systemic sclerosis. Furthermore, we show that MCTD-associated CpGs are potential epigenetic biomarkers with high diagnostic value. Our study serves to reveal new genes and pathways involved in MCTD, to illustrate the important role of epigenetic modifications in MCTD pathology, in mediating the interaction between different genetic and environmental MCTD risk factors, and as potential biomarkers of SADs.

Pregnancy outcomes in mixed connective tissue disease: a multicentre study.

OBJECTIVES: In this study we aimed to investigate foetal and maternal pregnancy outcomes from a large multicentre cohort of women diagnosed with MCTD and anti-U1RNP antibodies. METHODS: This multicentre retrospective cohort study describes the outcomes of 203 pregnancies in 94 consecutive women ever pregnant who fulfilled the established criteria for MCTD with confirmed U1RNP positivity. RESULTS: The foetal outcomes in 203 pregnancies were as follows: 146 (71.9%) live births, 38 (18.7%) miscarriages (first trimester pregnancy loss of <12 weeks gestation), 18 (8.9%) stillbirths (pregnancy loss after 20 weeks gestation) and 11 (5.4%) cases with intrauterine growth restriction. Maternal pregnancy outcomes were as follows: 8 (3.9%) developed pre-eclampsia, 2 (0.9%) developed eclampsia, 31 (15.3%) developed gestational hypertension and 3 (1.5%) developed gestational diabetes. Women with MCTD and aPL and pulmonary or muscular involvement had worse foetal outcomes compared with those without. Moreover, we report a case of complete congenital heart block (0.45%) and a case of cutaneous neonatal lupus, both born to a mother with positive isolated anti-U1RNP and negative anti-Ro/SSA antibodies. CONCLUSION: In our multicentre cohort, women with MCTD had a live birth rate of 72%. While the true frequency of heart block associated with anti-U1RNP remains to be determined, this study might raise the consideration of echocardiographic surveillance in this setting. Pregnancy counselling should be considered in women with MCTD.

Anca negative pauci-immune crescentic glomerulonephritis and mixed connective tissue disease: a case study.

One of the most common causes of rapidly progressive glomerulonephritis (RPGN) is pauci-immune crescentic glomerulonephritis (CrGN). In the majority of cases, this condition has a positive serologic marker, the anti-neutrophil cytoplasmic antibodies (ANCAs), but in approximately 10% there are no circulating ANCAs, and this subgroup has been known as the ANCA-negative pauci-immune CrGN. RPGN can be associated with systemic diseases, but there are only few case reports describing the association with mixed connective tissue disease (MCTD). The authors report a case of ANCA-negative CrGN associated with a MCTD.

Autoimmunity and immunodeficiency at the crossroad: autoimmune disorders as the presenting feature of selective IgM deficiency.

Selective immunoglobulin M deficiency (sIgMD) is an immunodeficiency with undefined pathogenesis and commonly presenting with recurrent infections. 1 The European Society for Immunodeficiencies Registry defines sIgMD as a serum IgM level repeatedly below 2 SD of normal with normal levels of serum IgA, IgG and IgG subclasses, normal vaccination responses, absence of T-cell defects and absence of causative external factors. Rarely it can also be associated with autoimmune diseases. 2-7 Here we describe a patient with primary sIgMD; who presented with multiple autoimmune diseases without a history of recurrent infections and we provide a short literature review on sIgMD and autoimmune diseases.

Clinical and immunological profile in patients with mixed connective tissue disease.

Mixed connective tissue disease (MCTD) is a rare disease and presents with varied overlapping symptoms of different connective tissue disorders. Many patients evolve into other connective tissue disorders with the passage of time. The case series included 20 patients with the diagnosis of MCTD, registered at the Rheumatology Clinic of Jinnah Postgraduate Medical Centre (JPMC), Karachi, from June 2010 to May 2015. Of these, 16 (80.0%) were female and 4 (20.0%) patients were male. The mean age was 30.5±8.9 years and the mean duration of illness was 4.5±2 years. Commonest presenting symptom was arthralgia in 17 (85%) patients. All the patients had positive ANA and anti-RNP antibodies. Over the disease course of 6 years, 2 (10%) patients evolved into Systemic lupus erythematosus (SLE); One each (5%) into Sjogren's syndrome, Scleroderma and Rheumatoid arthritis.

The impact of anti-U1-RNP positivity: systemic lupus erythematosus versus mixed connective tissue disease.

Anti-U1-RNP positivity remains mandatory for the mixed connective tissue disease (MCTD) diagnosis, reason for which anti-U1-RNP occurrence in patients with lupus clinical features might determine diagnostic issues. Thus, the prevalence of 25-30% for anti-RNP was reported in John Hopkins and LUMINA lupus cohorts and also 13% prevalence for the anti-U1-RNP in Euro-Lupus cohort. Presence of anti-U1-RNP antibodies in patients fulfilling SLE criteria (but not the MCTD ones) was associated with manifestations such as Raynaud phenomenon, musculoskeletal and lung impairment or nail fold capillaroscopy changes, some clinical features frequently encountered in MCTD patients and only rarely described in lupus population. The use of more specific markers such as 70 kDa anti-U1-RNP or anti-Sm-D was proposed for discriminating between SLE and MCTD. In addition, the IgM serotype of anti-U1-RNP seems more frequently expressed in SLE, while the IgG serotype alone in MCTD. Better acknowledgement of possible clinical involvements in lupus subsets, such as the peculiarities related to the anti-U1-RNP positivity, could provide access to early diagnosis of rather rare but possible severe lupus organ impairments (e.g. pulmonary arterial hypertension).

Progression and mortality of interstitial lung disease in mixed connective tissue disease: a long-term observational nationwide cohort study.

Objectives: To assess the prevalence, extent, progression, functional impact and mortality of interstitial lung disease (ILD) in a nationwide unselected MCTD cohort. Methods: The study cohort included patients with high-resolution CT lung scans available at baseline (n = 135) and at follow-up (n = 119). The extent of disease was expressed as percentage of total lung volume (TLV). Results: ILD was present in 41% of MCTD patients at follow-up. Median (interquartile) extent (% of TLV) was 5 (8) at baseline and 7 (17) at follow-up, mean length 6.4 years later. The lung disease progressed in 19% of patients across the observation period. Predictors of ILD progression were elevated anti-RNP titre [hazard ratio (HR) 1.5, 95% CI: 1.1, 2.0; P = 0.008], presence of anti-ro52 antibodies (HR = 3.5, 95% CI: 1.2, 10.2; P = 0.023), absence of arthritis (HR = 0.2, 95% CI: 0.1, 0.6; P = 0.004) and male gender (HR = 4.0, 95% CI: 1.4, 11.5; P = 0.011) after age and baseline disease adjustments. The risk of death increased by 2.9 (95% CI: 1.1, 7.9; P = 0.038) in patients where disease involved ⩾5% of TLV. Conclusion: Lung disease extent and progression in MCTD are modest. Yet, the extension continues several years after MCTD diagnosis causing lung function decline and increasing the risk of mortality. The study identified male gender, elevated anti-RNP titre, presence of anti-ro52 antibodies and absence of arthritis as the strongest predictors of ILD progression.