The patient, a 72-year-old retired nurse, was in good health with no history of alcohol or tobacco use, chronic lung disease, immune disease, family history, and no complaints of muscle pain or weakness. The patient was admitted to our hospital with symptoms of fever, cough, and shortness of breath. Upon examination (Table 1), the patient showed elevated levels of white blood cells and C-reactive protein, and tested negative for SARS-Cov-2 swabs. The patient was diagnosed with community-acquired pneumonia and treated with laroxefin for anti-infection. However, the patient's dyspnea worsened during treatment. On the third day, the patient required non-invasive ventilator assisted ventilation, and the SARS-Cov-2 swab was tested positive again. The chest CT examination revealed ground glass shadow changes (Figure 1), and the patient was immediately treated with azivudine 5mg/day for novel coronavirus infection.Azvudine is a small-molecule antiviral drug taken orally, developed independently in China. It is metabolized into active Azvudine triphosphate in cells and specifically targets the RNA-dependent polymerase of the novel coronavirus, effectively blocking or terminating its replication. Additionally, a daily dose of 40mg of methylprednisolone sodium succinate for injection is administered to reduce alveolar effusion, along with anticoagulant therapy of 4000IU/day of Enoxaparin sodium. However, the patient's condition continued to worsen. While using a non-invasive ventilator for assistance, the patient's oxygen concentration remained at 100%, but their oxygen saturation was still only around 70%, and the lowest oxygenation index was only 80. On the 10th day, the patient was moved to the intensive care unit following endotracheal intubation. A re-evaluation of the chest CT scan revealed extensive interstitial fibrosis changes in both lungs (Figure 2). We continued the treatment with methylprednisolone sodium succinate for injection at a dosage of 40mg/day for its anti-inflammatory effects, enoxaparin sodium at a dosage of 4000IU/day for anticoagulation, along with prone positioning, imipenem and cilastatin sodium for anti-sensitivity combined with voriconazole for anti-infection, and compound sulfamethoxazole for the prevention of pneumocystis infection. To determine the cause, we recommended a lung tissue biopsy to the patient's family, but they declined. After a thorough physical examination, we discovered that the patient was unable to participate in the muscle strength assessment due to sedation and analgesia, and no rash was observed on the entire body. However, we noticed significant roughness and thickening of the skin on the patient's fingers, along with evident keratinization changes (Figure 3). At this point, we began to suspect a potential combination of novel coronavirus infection and autoimmune diseases. We conducted auxiliary autoimmune-related tests (Table 2), and the results of the patient's autoimmune antibody spectrum revealed positive antinuclear antibody (ANA) and anti-recombinant RO-52 antibody (+++). Considering the changes in the skin on the patient's fingers, we have a strong suspicion of dermatomyositis. Therefore, we promptly conducted a myositis-specific antibody spectrum test, which yielded a positive result for anti-PL-12 using the immunoprecipitation method (Table 3). As per Solomon et al. [4], the patient tested positive for anti-PL-12, and the patient's chest CT scan indicated interstitial lung disease, which is a key criterion. This contributes to a secondary diagnosis, and patients can be diagnosed with AS as outlined above. Subsequently, we continued using methylprednisolone sodium succinate for injection at a dosage of 80mg per day, cyclophosphamide for injection at a dosage of 0.4g per day, and Nidanib softgel ethanesulfonate at a dosage of 150mg twice a day for anti-fibrosis therapy, while reducing the anti-infection regimen. The patient's oxygenation index improved from day 16 of admission (Figure 4), interstitial fibrosis showed significant improvement based on chest CT review (Figure 5), and the tracheal tube was successfully removed on day 22. At 30 days, the patient only required intermittent nasal catheter oxygen (2L/min), and we discontinued methylprednisolone sodium succinate, switching to oral prednisone tablets at a dosage of 30mg per day. The patient was successfully discharged from the hospital. After discharge, the patient gradually reduced the dosage of prednisone tablets by 5mg per week and stopped taking prednisone tablets after 6 weeks. Finally, we followed up with the patient, who no longer required oxygen therapy, resumed their normal daily activities, and was able to engage in a small amount of physical activity.