Objective:To explore the clinical characteristics, diagnosis and treatment strategies, and prognosis of pulmonary embolism (PE) complicating childhood rheumatic diseases.Methods:A retrospective case series study was performed on the demographic data, laboratory indicators, imaging features, treatment regimens, and follow-up data of 8 children with rheumatic diseases complicated by PE who were admitted to the Department of Rheumatology and Immunology, Capital Center for Children′s Health, Capital Medical University from January 2014 to October 2023.Results:Among the 8 children, there were 4 boys and 4 girls, with an age of 12.0 (7.5, 13.0) years. Among the primary diseases, there were 3 cases of systemic lupus erythematosus, 2 cases of Beh?et′s disease, 2 cases of Takayasu arteritis, and 1 case of antiphospholipid syndrome. All children developed PE during the active phase of the primary disease. PE was detected at the onset of the primary disease in 3 cases, and the median time from the diagnosis of the primary disease to the development of PE was 10.0 (6.0, 25.0) months in the remaining 5 cases. Fever was present in all 8 children, 4 cases were accompanied by chest tightness, dyspnea, etc., and 2 cases only presented with fever. Laboratory examinations revealed the following results: erythrocyte sedimentation rate was 42.0 (17.0, 78.0) mm/1 h, high-sensitivity C-reactive protein was 12.7 (2.6, 78.7) mg/L, white blood cell count was 9.6 (7.2, 18.7)×10 9/L; D-dimer was 2.3 (0.9, 6.2) mg/L; and hemoglobin was (109±16) g/L.Imaging examinations revealed that 5 cases had involvement of the bilateral lower pulmonary arteries, 5 cases had peripheral embolism, and 3 cases had central PE. Complications included 3 cases of deep vein thrombosis, 2 cases of intracranial venous sinus thrombosis, and 1 case of mild pulmonary hypertension.In terms of treatment, 7 cases received anticoagulation with heparin followed by warfarin. Immunomodulation was mainly based on glucocorticoids combined with immunosuppressants, and 4 cases were combined with biological agents. The follow-up time of 4.17 (1.75, 7.17) years, the time for complete absorption of PE was 10.5 (6.0, 18.0) months; all 8 children had no target events, with no recurrence or chronic thromboembolic pulmonary hypertension, and the pulmonary artery remodeling was good. Conclusions:PE complicating childhood rheumatic diseases is closely related to the activity of the primary disease. The clinical manifestations are insidious, with fever as the main symptom. Imaging examination is the key to diagnosis.Early adoption of heparin followed by warfarin anticoagulation and glucocorticoids combined with immunosuppressants and (or) biological agents to control the primary disease can achieve a favorable prognosis.

Gout is a crystal-associated arthropathy caused by the deposition of monosodium urate crystals and is closely related to purine metabolic disorders and impaired uric acid excretion. It is clinically characterized by hyperuricemia， recurrent joint swelling and pain， and tophus formation. The disease course is divided into three stages： The hyperuricemia stage， acute attack stage， and chronic gouty arthritis stage. Modern medicine has reached a consensus on its pathology， but traditional Chinese medicine （TCM） lacks a systematic stage-specific understanding of gout pathogenesis and its underlying mechanisms， making it difficult to guide precise syndrome differentiation and treatment. By integrating classical TCM theory， clinical practice， and modern medical understanding， and drawing upon descriptions of Bi syndrome caused by endogenous dampness and turbidity in classical texts such as Huangdi Neijing·Ling Shu and Synopsis of the Golden Chamber， our team proposes the pathogenic concept of gout as ''endogenous dampness leading to Bi syndrome'' and the core pathogenesis of ''spleen deficiency with internal retention of dampness-turbidity''. We systematically elucidate the evolution of pathogenesis across different stages and corresponding therapeutic strategies. This study posits that metabolic byproducts such as urate fall under the category of ''endogenous pathogenic dampness-turbidity''. When genetic or dietary factors lead to metabolic abnormalities， it manifests as ''spleen deficiency with impaired transport and transformation''， resulting in ''internal retention of pathogenic dampness-turbidity''. When damp-turbidity stagnates in the blood vessels， serum uric acid levels rise. When it stagnates in the viscera and limbs， monosodium urate crystals deposit in the joints. Triggered by precipitating factors， this leads to gout attacks—the core pathological process of ''endogenous dampness leading to Bi syndrome''. Based on this theory， the stage-specific pathogenic characteristics of gout are proposed： The hyperuricemia stage is characterized by ''spleen deficiency with impaired transport and transformation， internal retention of pathogenic dampness-turbidity''， the acute attack stage is primarily marked by ''dampness-turbidity and static heat obstructing the limbs and joints''， while the chronic stage is defined by ''spleen deficiency with internal retention of pathogenic dampness-turbidity， intermingled with phlegm-stasis binding''. The treatment principle centers on ''strengthening the spleen and draining dampness'' throughout all stages. During the hyperuricemia stage， treatment focuses on ''strengthening the spleen， draining dampness， and eliminating turbidity''. In the acute attack stage， the treatment should "strengthen the spleen， drain dampness， clear heat， eliminate turbidity， alleviate swelling， and relieve pain''. In the chronic stage， the treatments emphasizes to ''strengthen the spleen， drain dampness， transform turbidity， clear heat， resolve phlegm， and activate blood circulation''. This approach has yielded favorable therapeutic outcomes in clinical practice. This theoretical system clarifies the nature of gout as ''spleen deficiency being the root， dampness-turbidity being the secondary manifestation'' and systematically analyzes its pathogenesis evolution process and characteristics. The constructed stage-based treatment protocol has been validated through clinical and basic research， providing systematic theoretical guidance and a practical framework for the precise TCM management of gout， thereby promoting the modernization of TCM pathogenesis theory related to gout.

ObjectiveTo evaluate the therapeutic effect of Huazhuo SanJie Chubi presciption （HSCD） on chronic gouty arthritis （CGA） rats with low-grade inflammation and to explore the underlying mechanism with a focus on macrophage polarization. MethodsThe 41 male 6-week-old SD rats were randomly allocated， using the random number table， to a normal group （n=8） and a model group （n =33）. CGA with low-grade inflammation was induced in the model group by daily gavage of potassium oxonate （250 mg·kg^-1·d^-1） and hypoxanthine （300 mg·kg^-1·d^-1）， combined with intra-articular injection of a monosodium urate （MSU） crystal suspension （50 μL， 25 g·L^-¹） into the left ankle twice weekly. After 4 weeks of modeling， 3 rats were randomly selected from each group for model validation. The remaining successfully modeled rats were randomly divided into a model group， an HSCD group （10.35 g·kg^-1·d^-1， gavage once daily）， an M1 polarization agonist group （L-methionine sulfoximine， 300 mg·kg^-1， subcutaneous injection every other day）， an M1 polarization agonist + HSCD group， an M2 polarization inhibitor group （PD0325901， 10 mg·kg^-1·d^-1， gavage once daily）， and M2 polarization inhibitor + HSCD group. The corresponding drug or drug combination was administered according to group assignment， whereas rats in the normal and model groups received 0.5% carboxymethyl cellulose sodium （CMC-Na） vehicle （10.35 g·kg^-1·d^-1， gavage once daily）. All interventions were continued for four weeks. During the intervention period， except for the normal group， potassium oxonate （250 mg·kg⁻¹） and hypoxanthine （300 mg·kg^-1） were co-administered by gavage every other day to maintain the model. At the end of treatment， serum uric acid （SUA）， ankle joint diameter and joint swelling index were measured. The levels of high-sensitivity C-reactive protein （hs-CRP）， interleukin-1β （IL-1β）， interleukin-6 （IL-6）， tumor necrosis factor-α （TNF-α）， chemokine C-C motif ligand 2 （CCL2）， S100 calcium-binding protein A8/A9 （S100A8/A9）， interleukin-10 （IL-10） and arginase-1 （Arg-1） in serum and joint fluid were determined by enzyme-linked immunosorbent assay （ELISA）. High-frequency ultrasound was used to assess MSU deposition in the ankle joint. Hematoxylin-eosin （HE） staining was performed to evaluate synovial histopathological changes. Quantitative Real-time PCR and immunofluorescence were used to detect the mRNA and protein expression of the M1 macrophage polarization markers inducible nitric oxide synthase （iNOS） and the M2 macrophage polarization marker scavenger receptor cysteine-rich type 1 protein M130 （CD163） in synovial tissue. ResultsCompared with the normal group， the model group showed significantly elevated SUA level and joint swelling index， and increased levels of pro-inflammatory cytokines， CCL2， and S100A8/A9 in both serum and joint fluid （P<0.05）， accompanied by MSU deposition and synovial inflammation in the ankle joint. The mRNA and protein expression levels of macrophage polarization M1/M2 markers iNOS and CD163 in synovial tissues were also significantly up-regulated （P<0.05）. Compared with model group， rats in HSCD group had significantly lower SUA levels， attenuated joint swelling， reduced serum levels of pro-inflammatory cytokines， and decreased levels of CCL2 and S100A8/A9 in both serum and joint fluid， accompanied with alleviated MSU deposition and synovial inflammation （P<0.05）. HSCD markedly downregulated the mRNA and protein expression of M1 marker iNOS （P<0.05）， whereas it had no significant effect on the expression of M2 marker CD163. Compared with the M1 polarization agonist group， the M1 polarization agonist + HSCD group showed significantly reduced joint swelling， lower serum levels of pro-inflammatory cytokines， and decreased levels of CCL2 and S100A8/A9 in joint fluid （P<0.05）. In addition， synovial inflammatory cell infiltration and angiogenesis were attenuated， and iNOS mRNA and protein expression levels were significantly reduced （P<0.05）. Compared with the M2 polarization inhibitor group， the M2 polarization inhibitor + HSCD group exhibited reduced joint swelling， decreased levels of CCL2 and S100A8/A9 in joint fluid and ameliorated synovial inflammation （P<0.05）， whereas the levels of anti-inflammatory mediators （IL-10， Arg-1） and CD163 mRNA and protein expression were not significantly increased. ConclusionHSCD alleviates low-grade inflammation in CGA rats， at least in part， by inhibiting macrophage polarization toward the M1 phenotype.

ObjectiveThis paper aims to observe the effect of Huazhuo Sanjie Chubi prescription （HSCD） on the gouty bone erosion model rats and investigate its action mechanism. MethodsThirty-six two-month-old male SD rats were randomly divided into the blank group with nine rats and the modeling group with 27 rats. The rats in the modeling group were administered hypoxanthine solution at 300 mg·kg^-1·d^-1 and potassium oxonate solution at 250 mg·kg^-1·d^-1， combined with intra-articular injection of 200 μL monosodium urate （MSU） crystal suspension at 25 g·L^-1 into the right ankle joint （joint injection once every three days）， so as to induce the gouty bone erosion model. After four weeks of modeling， three rats were selected from these two groups to validate the model. The modeled 24 rats were randomly divided into the model group， HSCD group （10.35 g·kg^-1·d^-1）， allopurinol group （20 mg·kg^-1·d^-1）， and inhibitor group （LY294002， 10 mg·kg^-1·d^-1）， with six rats per group. Except for the blank group， rats in all other groups continued to receive hypoxanthine solution at 300 mg·kg^-1 and potassium oxonate solution at 250 mg·kg^-1 via gavage concurrently with administration to maintain modeling intervention. The rats in the HSCD group and allopurinol group received administration by gavage at the above doses. The rats in the inhibitor group received an intraperitoneal injection at the above dose. The rats in the blank group and model group received saline （10.35 g·kg^-1·d^-1） by gavage for four consecutive weeks. After administration， ankle joint swelling of the rats in all groups was observed， and the diameters were measured. Bone volume fraction （BV/TV） and bone surface area to bone volume （BS/BV） were observed and quantitatively analyzed by Micro-CT. Histopathological changes in the ankle joint were observed by hematoxylin-eosin （HE） staining and safranin O-fast green staining. The uric acid in the rats' serum was determined by enzyme colorimetry. The levels of inflammatory factors， including tumor necrosis factor-α （TNF-α）， interleukin （IL）-1β， and IL-6 were measured by enzyme-linked immunosorbent assay （ELISA）. The protein expressions of receptor activator of nuclear factor-κB ligand （RANKL） and phosphorylated （p）-phosphatidylinositol-3-kinase （PI3K） in ankle joint tissues of rats were detected by immunofluorescence staining. The mRNA levels of the proteins related to the bone erosion， including RANKL， tartrate-resistant acid phosphatase （TRAP）， cathepsin K （CTSK）， and matrix metalloproteinase-9 （MMP-9） in the ankle joint tissues of rats were determined by real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）. The expressions of the proteins related to the bone erosion， including RANKL， CTSK， TRAP， MMP-9， and the proteins related to the PI3K/protein kinase B （Akt） signaling pathway， including PI3K， Akt， mammalian target of rapamycin （mTOR）， p-PI3K， phosphorylated protein kinase B （p-Akt）， and phosphorylated mammalian target of rapamycin （p-mTOR）， were detected by Western blot. ResultsCompared with the blank group， the modeling group showed marked ankle swelling and increased diameter. Micro-CT revealed an uneven articular surface and honeycomb-like bone erosion in the ankle joint. Quantitative analysis showed decreased BV/TV and increased BS/BV （P<0.05）. HE staining revealed a narrowed joint space， rough and discontinuous cartilage surfaces， reduced and unevenly distributed chondrocytes， partial hypertrophy， and blurred tidemarks， confirming successful model establishment. After four weeks of intervention， compared with those in the blank group， the rats in the model group exhibited severe ankle swelling and increased diameters （P<0.05）. Micro‑CT showed that the ankle joint surface was irregular， and bone erosion exhibited a honeycomb‑like morphology. The microstructural parameters of the bone revealed a decreased BV/TV and an increased BS/BV （P<0.05）. Histopathological examination revealed a narrowed joint space and severe articular cartilage destruction. The levels of uric acid in the serum and inflammatory factors （IL-1β， IL-6， and TNF-α） were increased （P<0.05）. The mRNA and protein levels of the proteins related to bone erosion in joint tissue， including RANKL， CTSK， TRAP， and MMP-9， were upregulated （P<0.05）. The ratios of p-PI3K/PI3K， p-Akt/Akt， and p-mTOR/mTOR in the proteins related to the PI3K/Akt signaling pathway were increased （P<0.05）. RANKL and p-PI3K protein fluorescence intensities were elevated （P<0.05）. Compared with those in the model group， the above indicators in all other administration groups showed varying degrees of improvement. The HSCD group and inhibitor groups exhibited more significant effects in reducing ankle swelling， improving bone erosion， bone microstructure （significant decrease in BV/TV and increase in BS/BV）， and the pathology of cartilage erosion， lowering inflammatory factor levels， downregulating the proteins related to the bone erosion， and suppressing activation of the PI3K/Akt/mTOR pathway （P<0.05）. The uric acid levels in rats' serum were reduced in both HSCD and allopurinol groups （P<0.05）. Compared with those in the HSCD group， the rats in the allopurinol group had larger ankle diameters （P<0.05）， more severe bone erosion and bone microstructure damage （P<0.05）， worse improvement of the pathology of cartilage erosion， higher levels of IL-6 and TNF-α （P<0.05）， elevated expressions of the proteins related to the bone erosion， higher expression ratio of proteins related to the PI3K/Akt signaling pathway （P<0.05）， and higher fluorescence intensities of RANKL and p-PI3K proteins （P<0.05）. The inhibitor group achieved comparable results to the HSCD group in improvements of bone microstructure and the reduction of IL-1β and IL-6， stronger suppression of TNF-α and PI3K/Akt/mTOR signaling pathway activation （P<0.05）， but weaker effects on cartilage repair and serum uric acid reduction （P<0.05）. ConclusionHSCD effectively reduces uric acid levels in serum， suppresses inflammatory factor secretion， and downregulates the expressions of proteins related to bone erosion， including RANKL， CTSK， TRAP， and MMP-9 in the joint tissues. Its action mechanism of improving gouty bone erosion may be associated with inhibition of the PI3K/Akt signaling pathway.

Objective To preliminary explore the imaging manifestations of digital breast tomosynthesis (DBT) and contrast-enhanced mammography (CEM) in triple-negative breast cancer (TNBC) patients with different levels of human epidermal growth factor receptor 2 (HER2) expression. Methods A retrospective analysis was conducted on TNBC patients who underwent preoperative DBT or CEM examinations at Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from January 2018 to December 2019 and Shanghai Second People’s Hospital from January 2022 to May 2025. Clinical data, pathological and immunohistochemical results, and imaging data were collected. Results A total of 69 TNBC patients pathologically confirmed as invasive ductal carcinoma were included, among which 34 underwent DBT and 35 underwent CEM. Among these patients, 34 (49.28%) had HER2-low expression and 35 (50.72%) had HER2-zero expression. DBT results showed that the proportion of spiculation signs in HER2-low group (n＝14) was significantly higher than that in HER2-zero group (n＝20; P＝0.009, P_adj＝0.045). However, there were no significant differences in breast density type, mass shape, or calcification between the two groups. CEM results showed that on low-energy images, the proportion of spiculation signs in the HER2-low group (n＝20) was higher than that in the HER2-zero group (n＝15; P＝0.011, P_adj＝0.077). Results of CEM showed that on reconstructed images, differences in background parenchymal enhancement and mass enhancement patterns between the two groups were not statistically significant; in both groups, heterogeneous enhancement was the most common, followed by homogeneous enhancement, with ring enhancement being the least common. Conclusions TNBC with low HER2 expression and TNBC with zero HER2 expression may have potential differences in the presentation of spiculation signs on DBT. However, the correlation between CEM manifestations and TNBC with different HER2 expression levels requires further research.

Objective:To explore the clinical characteristics, diagnosis and treatment strategies, and prognosis of pulmonary embolism (PE) complicating childhood rheumatic diseases.Methods:A retrospective case series study was performed on the demographic data, laboratory indicators, imaging features, treatment regimens, and follow-up data of 8 children with rheumatic diseases complicated by PE who were admitted to the Department of Rheumatology and Immunology, Capital Center for Children′s Health, Capital Medical University from January 2014 to October 2023.Results:Among the 8 children, there were 4 boys and 4 girls, with an age of 12.0 (7.5, 13.0) years. Among the primary diseases, there were 3 cases of systemic lupus erythematosus, 2 cases of Beh?et′s disease, 2 cases of Takayasu arteritis, and 1 case of antiphospholipid syndrome. All children developed PE during the active phase of the primary disease. PE was detected at the onset of the primary disease in 3 cases, and the median time from the diagnosis of the primary disease to the development of PE was 10.0 (6.0, 25.0) months in the remaining 5 cases. Fever was present in all 8 children, 4 cases were accompanied by chest tightness, dyspnea, etc., and 2 cases only presented with fever. Laboratory examinations revealed the following results: erythrocyte sedimentation rate was 42.0 (17.0, 78.0) mm/1 h, high-sensitivity C-reactive protein was 12.7 (2.6, 78.7) mg/L, white blood cell count was 9.6 (7.2, 18.7)×10 9/L; D-dimer was 2.3 (0.9, 6.2) mg/L; and hemoglobin was (109±16) g/L.Imaging examinations revealed that 5 cases had involvement of the bilateral lower pulmonary arteries, 5 cases had peripheral embolism, and 3 cases had central PE. Complications included 3 cases of deep vein thrombosis, 2 cases of intracranial venous sinus thrombosis, and 1 case of mild pulmonary hypertension.In terms of treatment, 7 cases received anticoagulation with heparin followed by warfarin. Immunomodulation was mainly based on glucocorticoids combined with immunosuppressants, and 4 cases were combined with biological agents. The follow-up time of 4.17 (1.75, 7.17) years, the time for complete absorption of PE was 10.5 (6.0, 18.0) months; all 8 children had no target events, with no recurrence or chronic thromboembolic pulmonary hypertension, and the pulmonary artery remodeling was good. Conclusions:PE complicating childhood rheumatic diseases is closely related to the activity of the primary disease. The clinical manifestations are insidious, with fever as the main symptom. Imaging examination is the key to diagnosis.Early adoption of heparin followed by warfarin anticoagulation and glucocorticoids combined with immunosuppressants and (or) biological agents to control the primary disease can achieve a favorable prognosis.

Based on the concept of "blood exhaustion" from The Inner Canon of Yellow Emperor （《黄帝内经》）， a three-stage syndrome differentiation and treatment strategy for cancer-related anorexia-cachexia syndrome is proposeed. In the cancer-induced anorexia stage， the pathogenesis is characterized by cancer consuming the spleen and stomach， leading to stagnation of transportation and transformation in the middle jiao （焦）. Treatment should focus on strengthening the spleen， promoting appetite， dispersing accumulation， and aiding digestion， with modified Zisheng Pills （资生丸） in Extensive Notes on Medicine from Xian Xing Studio （《先醒斋医学广笔记》） or Zisheng Decoction （资生汤） in Records of Chinese Medicine with Reference to Western Medicine （《医学衷中参西录》）. In the pre-cachectic stage of malnutrition， the pathogenesis involves insufficient nourishment of blood and qi with essence depletion hindering production. Treatment should focus on nourishing blood and harmonizing ying （营）， warming yang and supplementing qi， and modified Huangqi Jianzhong Decoction （黄芪建中汤） can be used. In the cachectic stage， the pathogenesis involves blood deficiency and essence exhaustion， with blood stasis obstructing the collaterals. The therapeutic approach should focus on tonifying deficiency and replenishing essence， unblocking collaterals， and removing stasis， and modified Buzhong Yiqi Decoction （补中益气汤） and Zuo Gui Beverage （左归饮） are suggested.

Objective:To investigate the current situation and changing trends of coal-burning-borne endemic fluorosis (coal-burning-borne fluorosis) areas in Henan Province, and evaluate the effectiveness of prevention and control measures.Methods:From 2019 to 2021, monitoring was carried out in all villages affected by coal-burning-borne fluorosis in Henan Province. A simple random sampling method was used to select 30 households in each affected village each year to investigate the use of stoves and the formation of related healthy living behaviors. According to the criteria of "Diagnosis of Dental Fluorosis" (WS/T 208-2011), all children aged 8 to 12 in the affected villages were examined for dental fluorosis. The evaluation for control and elimination of the disease areas was carried out in accordance with the "Evaluation Approach for Control and Elimination of Priority Endemic Diseases (2019 Edition)".Results:From 2019 to 2021, a total of 7 472 households were monitored, the rate of qualified improved stoves were all ≥99.80%, the correct use rate of qualified improved stoves and correct drying of corn and pepper were reached 100%. From 2019 to 2021, the prevalence of dental fluorosis in children was 5.38% (237/4 405), 5.18% (232/4 477), and 3.68% (145/3 937), respectively, showing a declining trend (χ 2trend = 12.73, P < 0.001). The prevalence of dental fluorosis among children in affected villages was less than 15%. From 2019 to 2021, all affected villages in coal-burning-borne fluorosis in Henan Province had met the elimination criteria. Conclusion:Coal-burning-borne fluorosis areas in Henan Province have been continuously eliminated, with significant prevention and control effects, and the disease has been effectively controlled.

Objective To investigate the association between extensive perivascular space(EPVS)burden in different locations and ischemic stroke(IS),its subtypes,and transient ischemic attack(TIA)through Mendelian randomization(MR)analysis.Methods The summary data from large-scale Genome-wide Association Studies(GWAS)and various MR methods were employed.We applied multivariable MR to mitigate potential confounding factors and conduct sensitivity analyses to enhance result robustness.Subsequently,meta-analysis was utilized to integrate causal relationships between EPVS burden in different locations and IS from various sources.Additionally,reverse MR was employed to observe the impact of various IS types on EPVS burden.Finally,linkage disequilibrium score regression was conducted to assess genetic correlations between exposures and outcomes.Results EPVS burden in both the white matter(OR=1.12,95％CI:1.01-1.25;P=0.04)and basal ganglia(OR=1.57,95％CI:1.30-1.89;P＜0.01)are significant risk factors for IS.EPVS burden in the basal ganglia is also a risk for IS(small-vessel)(OR=4.56,95％CI:2.57-8.27;P=5.95× 10-7).After IS and TIA there seems to be a potential increase in extensive basal ganglia perivascular space burden.Conclusions Extensive white matter perivascular space burden and extensive basal ganglia perivascular space burden may serve as important indicators to predict IS.

Objective:To analyze the clinical characteristics of anti-melanoma differentiation associated gene 5 (MDA5) antibody-positive juvenile dermatomyositis (JDM) patients.Methods:A retrospective case-control study was conducted. The positive group included 18 children with anti-MDA5 antibody-positive JDM who were admitted to the Department of Rheumatology and Immunology at Capital Center for Children′s Health with Capital Medical University between January 2016 and January 2023. Another 36 children with anti-MDA5 antibody-negative JDM hospitalized during the same period were enrolled as the negative group. Based on the extent of pulmonary involvement and pulmonary CT scores, the MDA5-positive group was further divided into severe pulmonary involvement and non-severe pulmonary involvement subgroups. Chi-square test and Kruskal-Wallis test were used to compare clinical features, laboratory test results between groups.Results:Among the 18 patients in the MDA5-positive group, 7 were male and 11 were female, with an age of onset of 5.0 (2.6, 9.4) years and disease duration of 6.0 (4.0, 9.3) months. The MDA5-negative group included 36 cases (14 male, 22 female), with an age of onset of 4.9 (2.0, 7.0) years and disease duration of 5.0 (1.8, 7.0) months. The MDA5-positive group exhibited significantly higher rates of arthritis, skin ulcers, and interstitial lung disease (ILD), along with elevated serum ferritin (SF) and erythrocyte sedimentation rate levels compared to the MDA5-negative group (9/18 vs. 11% (4/36), 6/18 vs. 3% (1/36), 16/18 vs. 33% (12/36), 327 (141, 518) vs. 131 (68, 257) μg/L, 17.5 (12.5, 26.8) vs. 11.0 (5.0, 13.0) mm/1 h, χ2=7.92, 7.41, 14.84, Z=2.50, 2.87, all P<0.05). Conversely, the MDA5-positive group had lower rates of muscle weakness and lower creatine kinase levels (5/18 vs. 75% (27/36), 58.5 (49.3, 97.5) vs. 225.0 (68.0, 695.5) U/L, χ2=11.08, Z=-2.94, both P<0.05). Severe pulmonary involvement 6 cases and non-severe pulmonary involvement subgroups 12 cases. Among the MDA5-positive patients, those in the severe pulmonary involvement subgroup had an older age at onset and higher rates of muscle weakness as well as hydroxybutyrate dehydrogenase (HBDH), lactate dehydrogenase (LDH), SF, and Krebs von den Lungen-6 (KL-6) compared to the non-severe subgroup (all P<0.05). In the MDA5-positive group, 17 patients improved after treatment with glucocorticoids combined with immunosuppressants, while One died due to rapidly progressive ILD. Conclusions:Anti-MDA5 antibody-positive JDM is characterized by typical skin rashes, a high incidence of arthritis and skin ulcers, relatively mild muscle involvement, but is prone to ILD. Among MDA5-positive patients, those with older age at onset, muscle involvement (manifested as muscle weakness and elevated muscle enzymes (LDH, HBDH)), or significantly elevated KL-6 and SF levels are more likely to develop severe pulmonary complications.