BACKGROUND: Mixed connective tissue disease (MCTD) is a rare entity in children. There is a paucity of studies on juvenile-onset MCTD (jMCTD) worldwide especially from Southeast Asia.
OBJECTIVE: To describe clinical and laboratory features of jMCTD diagnosed at pediatric rheumatology centers across India.
METHODS: A predesigned detailed case proforma in an excel format was prepared and was sent to all the Pediatric Rheumatology centers in India. Eleven centers provided the clinical and laboratory data of their jMCTD patients, which was then compiled and analyzed in detail.
RESULTS: Thirty-one jMCTD patients from 11 centers were included in the study. Our cohort had 27 females and four male patients over 12 months (August 2021 to July 2022). The median age at presentation was 12 years (range 5-18 years) and the median duration of symptoms was 24 months at diagnosis (range 2-96 months). The common features included arthritis (90%), malar rash (70.9%), and Raynaud\'s phenomenon (70.9%). At a mean follow-up of 43 months (range 1-168 months), 45% of them were in remission. There were two deaths reported, due to macrophage activation syndrome and sepsis respectively.
CONCLUSIONS: We present the largest multicenter experience on jMCTD from the Indian subcontinent. The study\'s findings serve as a crucial stepping stone toward unraveling the complexities of jMCTD and improving patient care and management strategies.

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.

Mixed connective tissue disease (MCTD) is characterized by mixed features of systemic lupus erythematosus, systemic sclerosis, and polymyositis/dermatomyositis and is rare in children. Here, we report a case of MCTD in a 10-year-old girl who presented at our hospital with arthralgia, Raynaud\'s phenomenon, and fatigue. Blood tests were positive for anti-U1-ribonucleoprotein (RNP) antibodies and for rheumatoid factors (RFs) IgG-RF and anti-galactose-deficient IgG. Levels of myogenic enzymes and hypergammaglobulinemia were elevated. Macrophages were prominent in bone marrow, with scattered phagocytic macrophages. MCTD was diagnosed based on the patient\'s symptoms and laboratory findings. Methylprednisolone pulse therapy combined with oral tacrolimus was administered, which led to resolution of symptoms. Three months after pulse therapy, arthralgia worsened and methotrexate was administered. Arthralgia improved but did not resolve. Magnetic resonance imaging performed to investigate the hip pain revealed a mature ovarian teratoma, which was surgically removed. Because the pain persisted and interfered with her daily life, she was treated with tocilizumab for joint pain relief, which decreased the pain level. Tocilizumab is a candidate for additional treatment of juvenile idiopathic arthritis-like arthritis associated with childhood-onset MCTD.

Overlapping autoimmune disorders are used to describe the coexistence of more than one autoimmune disease in the same patient. Mixed connective tissue disease (MCTD) and anti-synthetase syndrome (ASS) are autoimmune diseases that manifest with pulmonary involvement, presenting as persistent dyspnea. The coexistence of both conditions in the same patient is extremely rare. We herein report a case of a 44-year-old female who was diagnosed with MCTD with features of ASS (anti-Jo-1 antibody) in the setting of rheumatoid arthritis (anti-cyclic citrullinated peptide (anti-CCP) antibody), which shows temporary breathing improvement following treatment with corticosteroid and mycophenolate mofetil. However, after the completion of mycophenolate mofetil, she was found to be anti-Jo-1 antibody negative and anti-CCP antibody positive. Our case emphasizes the need to recognize overlapping autoimmune conditions in patients with complex clinical features and presentations with the immediate application of a comprehensive diagnostic approach and tailored treatment strategies. Early diagnosis and aggressive treatment are crucial for achieving remission and preventing organ damage.

UNASSIGNED: To investigate the clinical features, severity and prognosis of interstitial lung disease (ILD) in patients with mixed connective tissue disease (MCTD).
UNASSIGNED: We performed a retrospective study on clinical data of MCTD patients admitted to China-Japan Friendship Hospital between October 2012 and October 2022. Data including long-term follow-up were retrieved from medical records. We compared MCTD patients with and without ILD in terms of clinical features, laboratory and imaging findings, severity and treatment response.
UNASSIGNED: A total of 59 patients were included, with a mean age of 46 years, among which 91.5% (n = 54) were females. Symptoms of pulmonary involvement were present in 44 patients (74.6%, 95% CI: 62.3-84.9%). Based on lung high-resolution computed tomography (HRCT), ILD was diagnosed in 39 (66.1%) patients, among which 31 (79.5%) showed nonspecific interstitial pneumonia (NSIP) as the radiological pattern, 21 (53.9%) showed a reticulation pattern, while 24 (61.5%) showed ground glass opacity (GGO). Eight (13.6%) patients had pulmonary arterial hypertension (PAH), and 7 (11.9%) had pleural effusions. Based on pulmonary function tests (PFTs), 27 patients were divided into the mild 13 (48.1%) and moderate 14 (51.9%) groups. Multivariate analysis showed that gastroesophageal reflux (GER; OR=5.28, p=0.010) and cough (OR=4.61, p=0.043) were the predictive factors for ILD. With a median follow-up of 50 months, the mortality rate was 2.38%.
UNASSIGNED: ILD is common in MCTD patients, with NSIP as the common imaging pattern. Patients with GER and cough are relevant factors in the development of ILD. The majority of MCTD patients with ILD are mild to moderate in severity.

Diagnostic accuracy is of the utmost importance, both in the clinical setting and for research purposes. Mixed connective tissue disease (MCTD), rheumatoid arthritis (RA), Sjogren\'s syndrome (SS), and overlap syndrome (OS) frequently exhibit symptoms that mimic those of other conditions. Unfortunately, there is no singular definitive test for diagnosing these connective tissue diseases (CTDs), necessitating the reliance on expert opinions. Further complicating the matter, these diseases have overlapping clinical and serological features, and some individuals with one autoimmune disease may develop additional autoimmune disorders, either concurrently or at a later stage of their ailment. Autoimmune diseases (ADs) may manifest as a single AD or, concurrently with other ADs, a condition named polyautoimmunity (polyA). Polyautoimmunity refers to the presence of numerous autoimmune disorders in a single patient. Multiple autoimmune syndrome (MAS) is a condition that occurs when three or more autoimmune illnesses coexist. Moreover, the coexistence of two or more ADs with classification criteria is named \"overt polyA,\" whereas the presence of autoantibodies not related to the index AD, without criteria fulfillment, is termed \"latent polyA.\" Furthermore, both conditions can exist simultaneously within an individual patient. This case report\'s findings underscore that patients exhibiting both latent and overt polyautoimmunity tend to group, exhibiting distinct clinical and immunological characteristics. Additionally, CTDs not only have overlapping features amongst their various subclasses but also tend to mimic other conditions due to an underlying chronic inflammatory state. This case study also attempts to highlight the diagnostic dilemmas faced in such situations.

BACKGROUND: Fractional exhaled nitric oxide (FeNO) has been extensively studied in various causes of pulmonary hypertension (PH), but its utility as a noninvasive marker remains highly debated. The objective of our study was to assess FeNO levels in patients with idiopathic pulmonary arterial hypertension (IPAH) and mixed connective tissue disease complicating pulmonary hypertension (MCTD-PH), and to correlate them with respiratory functional data, disease severity, and cardiopulmonary function.
METHODS: We collected data from 54 patients diagnosed with IPAH and 78 patients diagnosed with MCTD-PH at the Shanghai Pulmonary Hospital Affiliated to Tongji University. Our data collection included measurements of brain natriuretic peptide (pro-BNP), cardiopulmonary exercise test (CPET), pulmonary function test (PFT), impulse oscillometry (IOS), and FeNO levels. Additionally, we assessed World Health Organization functional class (WHO-FC) of each patient.
RESULTS: (1) The fractional exhaled concentration of nitric oxide was notably higher in patients with IPAH compared to those with MCTD-PH. Furthermore, within the IPAH group, FeNO levels were found to be lower in cases of severe IPAH compared to mild IPAH (P = 0.024); (2) In severe pulmonary hypertension as per the WHO-FC classification, FeNO levels in IPAH exhibited negative correlations with FEV1/FVC (Forced Expiratory Velocity at one second /Forced Vital Capacity), MEF50% (Maximum Expiratory Flow at 50%), MEF25%, and MMEF75/25% (Maximum Mid-expiratory Flow between 75% and 25%), while in severe MCTD-PH, FeNO levels were negatively correlated with R20% (Resistance at 20 Hz); (3) ROC (Receiving operator characteristic curve) analysis indicated that the optimal cutoff value of FeNO for diagnosing severe IPAH was 23ppb; (4) While FeNO levels tend to be negatively correlated with peakPETO2(peak end-tidal partial pressure for oxygen) in severe IPAH, in mild IPAH they had a positive correlation to peakO2/Heart rate (HR). An interesting find was observed in cases of severe MCTD-PH, where FeNO levels were negatively correlated with HR and respiratory exchange ratio (RER), while positively correlated with O2/HR throughout the cardiopulmonary exercise test.
CONCLUSIONS: FeNO levels serve as a non-invasive measure of IPAH severity. Although FeNO levels may not assess the severity of MCTD-PH, their significant makes them a valuable tool when assessing severe MCTD-PH.

OBJECTIVE: 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.

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.

Mixed connective tissue disease (MCTD) is a rare autoimmune condition. Since its first description 50 years ago, its mere existence has been debated, given that it shares features of other autoimmune diseases, such as systemic lupus erythematosus (SLE), systemic sclerosis, inflammatory myopathy, rheumatoid arthritis and Sjogren\'s syndrome. Also, while antibodies to U1-RNP are essential for the diagnosis of MCTD, these antibodies may be expressed in other circumstances, such as in case of SLE. Nevertheless, the patient fulfilling criteria for MCTD needs specific management. In this review, we describe the clinical features and the potential complications of this complex disease, often wrongly disregarded as benign. We will also emphasize the recommended follow-up exams and address treatment, which is currently lacking formal recommendations.
La connectivite mixte (mixed connective tissue disease (MCTD)) est une maladie auto-immune rare. Dès sa description il y a cinquante ans, l’existence propre de la MCTD est débattue, car les limites avec d’autres maladies, comme le lupus érythémateux systémique (LES), la sclérodermie, les myopathies inflammatoires, la polyarthrite rhumatoïde et le syndrome de Sjögren, sont floues. Les anticorps anti-U1-RNP obligatoires au diagnostic de MCTD sont également exprimés dans d’autres circonstances, comme le LES. Quoi qu’il en soit, le patient présentant des critères de MCTD nécessite une prise en charge spécifique. Nous présentons ici les signes cliniques et complications potentielles d’une maladie longtemps estimée à tort comme d’évolution bénigne. Nous abordons aussi les examens de suivi recommandés et la thérapeutique, qui reste à ce jour mal définie.