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Dermatomyositis (DM) is characterized by skin lesions, skeletal muscle inflammation, and involvement of other organs. The pathogenesis of DM includes susceptibility genes, environmental stressors, immune and non⁃immune inducing mechanisms. DM usually presents as subacute progressive proximal muscle weakness, skin rash, or both. Other common extramuscular findings include various heart abnormalities, interstitial lung disease (ILD), and malignant tumors. The auxiliary examination of DM includes the examination of myositis autoantibodies, myoenzymes and electromyography (EMG). Skin treatments for DM include photosensitivity inhibition drugs and antimalarial drugs. If the DM is associated with muscle involvement, systemic corticosteroids is the first line of treatment, and immunosuppressants are used for refractory diseases or as corticosteroids sparing agents in the event of side effects. Other treatments include oral calcineurin inhibitors, cyclophosphamide, biologic agents and Janus kinase (JAK) inhibitor.

The Shimadong porphyry Mo deposit is located in eastern Yanbian, in the eastern part of the north margin of the North China craton, northeastern China. Here, we present the whole-rock major and trace elements, zircon U-Pb and Hf isotope data, and molybdenite Re-Os data for the Shimadong deposit. The porphyry was emplaced at 163.7 [+ or -] 0.9 Ma and the mineralization at 163.1 [+ or -] 0.9 Ma, suggesting that the mineralization was associated with the emplacement of the Shimadong porphyritic monzogranite. The porphyritic monzogranite had high Si[O.sub.2] (70.09-70.55 wt%) and [K.sub.2]O + [Na.sub.2]O (7.98-8.27 wt%) contents and low MgO (0.51-0.53 wt%), TFeO (2.4-2.47 wt%), CaO (2.19-2.26 wt%), and [K.sub.2]O/[Na.sub.2]O (0.8-0.82) contents. The porphyry was rich in large ion lithophile elements Rb, Ba, K, and Sr, depleted in high-field-strength elements Y, Nb, Ta, P, and Ti, without significant Eu anomaly (8Eu = 0.86-1.00), and depleted in heavy rare earth elements with light rare earth elements/heavy rare earth elements = 18.25-20.72 and [(La/Yb).sub.N] = 27.10-34.67. These features are similar to those of adakitic rocks derived from a thickened lower crust. Zircon eHf(t) values for the porphyritic monzogranite ranged from -19.2 to 6.3, and the two-stage Hf model ages ([T.sub.DM2]) were 2421-811 Ma. These data indicate that the primary magma of the Shimadong porphyritic monzogranite was mainly derived from partial melting of the thickened lower crust consisting of juvenile crust and pre-existing crust. Combined with the results of previous studies, our data suggest that the Shimadong porphyry Mo deposit was emplaced along an active continental margin related to the westward subduction of the paleo-Pacific Plate. Key words: zircon U-Pb dating, molybdenite Re-Os dating, geochemistry, Hf isotope, Shimadong porphyry Mo deposit, northeastern China. Le gisement porphyrique de Mo de Shimadong est situe dans le Yanbian oriental, dans la partie est de la bordure nord du craton de Chine du Nord. Nous presentons la geochimie des elements majeurs et en traces sur roche totale, des donnees d'U-Pb et d'isotopes de Hf dans les zircons et des donnees de Re-Os dans la molybdenite pour le gisement de Shimadong. Le porphyre a ete mis en place a 163,7 [+ or -] 0,9 Ma, et la mineralisation, a 163,1 [+ or -] 0,9 Ma, ce qui indiquerait que la mineralisation etait associee a la mise en place du monzogranite porphyrique de Shimadong. Ce dernier presente de fortes concentrations de Si[O.sub.2] (70,09-70,55 % poids) et [K.sub.2]O + [Na.sub.2]O (7,98-8,27 % poids) et de faibles concentrations de MgO (0,51-0,53 % poids), TFeO (2,4-2,47 % poids) et CaO (2,19-2,26 % poids), ainsi que de faibles rapports [K.sub.2]O/[Na.sub.2]O (0,8-0,82). Le porphyre a de fortes concentrations des elements lithophiles a grand rayon ionique Rb, Ba, K et Sr, et de faibles concentrations des elements a forte liaison atomique Y, Nb, Ta, P, et Ti, ne presente pas d'anomalie significative en Eu (2 8Eu = 0,86-1,00) et est appauvri en terres rares lourdes, donnant des rapports terres rares legeres/terres rares lourdes de 18,25-20,72 et des rapports [(La/Yb).sub.N] de 27,10-34,67. Ces caracteristiques sont semblables a celles de roches adakitiques derivees d'une croute inferieure epaissie. Les valeurs de eHf(t) des zircons du monzogranite prophyrique vont de -19,2 a 6,3, et les ages de Hf pour un modele en deux etapes ([T.sub.DM2]) vont de 2421 a 811 Ma. Ces donnees indiquent que le magma primaire du monzogranite porphyrique de Shimadong est principalement derive de la fusion partielle d'une croute inferieure epaissie constituee de croute juvenile et de croute preexistante. Combinees aux resultats d'etudes anterieures, nos donnees donnent a penser que le gisement porphyrique de Mo de Shimadong a ete mis en place le long d'une marge continentale active associee a la subduction vers l'ouest de la plaque paleo-Pacifique. [Traduit par la Redaction] Mots-cles: datation U-Pb sur zircon, datation Re-Os sur molybdenite, geochimie, isotopes du Hf, gisement porphyrique de Mo de Shimadong, nord-est de la Chine., Introduction One of the largest molybdenum (Mo) metallogenic belts in northeastern China, the eastern Xingmeng orogenic belt (EXOB) is a segment of the eastern Central Asian orogenic belt (Mao et [...]

The Triassic igneous complexes in the east flank of the East Kunlun orogenic belt (E-KOB) provide a window through which to investigate the Mesozoic magmatism in the E-KOB. Here, we report the precise timing of Triassic magmatism and magma petrogenesis of different rock types in the east flank of the E-KOB based on the petrology, mineral chemistry, geochemistry, zircon geochronology and Lu-Hf isotopes. Zircon U-Pb dating reveals that the Daheba complex was crystallized in 242–239 Ma. The rocks display enrichment in large-ion lithophile elements (LILEs) and LREEs and depletion in high field strength elements (HFSEs) and HREEs, which are typical of subduction-related magmatic rocks. The fine-grained granites (FGs) are characterized by a high SiO2 content (72.25–74.28 wt. %), a high differentiation index (DI = 95) and marked depletion in Sr, Ba and Eu, which indicates that the FGs are highly fractionated I-type granitoids. The zircon εHf(t) values from −3.6 to −1.1 with two-stage model ages (TDM2) of 1496–1340 Ma, which suggests that they were derived from an ancient Mesoproterozoic lower crust. The similarity in the REE patterns of the mafic microgranular enclaves (MMEs) and host granites (HGs) indicates that the mixing between mafic and felsic magmas could have contributed to the chemical variation of the MMEs. The mafic melts were derived from the partial melting of the mantle that had been metasomatized by slab-derived fluids. The MMEs show typical igneous textures, acicular apatites, sieve texture of plagioclase and reverse zoning of plagioclase, which correspond to magma mixing during petrogenesis. Our geochemical and isotopic data suggest that the Daheba complex formed in an active continental margin setting closely related to the northward subduction of the Palaeo-Tethys Ocean Plate beneath the E-KOB. [ABSTRACT FROM AUTHOR]