In July 2022, a 52-year-old woman was diagnosed with SLE, lupus nephritis, and polyserositis. She presented with symptoms of facial edema, anorexia, nausea, abdominal distention, cough, and white phlegm. The severity of her condition was measured using the SLE Disease Activity Index (SLEDAI), which scored 20. Initially, the patient received treatment with glucocorticoids (methylprednisolone, prednisone), immunosuppressants (cyclosporine, mycophenolate mofetil), and hydroxychloroquine sulfate. After confirming no contraindications such as infection or allergies, the patient began receiving belimumab (480mg) on July 22, 2022. Four rounds of therapy were completed by September 29, 2022. During this period, the patient's symptoms gradually improved, and her SLEDAI score decreased. As a result, the dosage of glucocorticoids and mycophenolate mofetil was gradually reduced. However, in October, the patient developed an infection with the herpes zoster virus. Although she did not experience a noticeable cough or expectoration, she had occasional chest tightness and mild shortness of breath. Before the fifth belimumab therapy, on November 1, 2022, a chest computed tomography scan revealed patchy, nodular, and flocculent ground-glass density shadows in all lung lobes, as well as nodules and cavities in the dorsal segment of the left lower lobe. These findings indicated pulmonary infiltration associated with SLE and pulmonary infectious lesions (Figure 1a and b). HIV and anti-IFN-gamma autoantibody test results were negative. White blood count and C-reactive protein were normal. Serum beta-D-glucan, serum galactomannan, cryptococcal capsular antigen, tuberculosis antibody, candida IgG antibody and candida antigen test were negative. CD4+T lymphocyte count was 332/ul (reference range, 180-324/ul), CD8+T lymphocyte count was 646/ul (reference range, 1185-1901/ul), absolute NK cell count was 16/ul (reference range, 200-587/ul), IgG 5.44 g/L (reference range, 8-18g/L), IgA 1.16g/L (reference range, 0.9-4.5g/L), IgM 0.64g/L (reference range, 0.84-1.32g/L). The next generation sequencing (NGS) of bronchoalveolar lavage fluid (BALF) showed that Pneumocystis jirovecii (sequence number 178940) and Talaromyces marneffei (sequence number 7480). TM was cultured from the patients' BALF (Figure 2a and b). Meanwhile, BALF was positive for PJ by polymerase chain reaction (PCR). Finally, we discontinued the fifth belimumab therapy. Voriconazole (0.6g/d on day 1 and 0.4g/d from day 2) was used to treat TM infection. She had a history of glucose-6-phosphate dehydrogenase deficiency. Therefore, PJ pneumonia was treated with clarithromycin 1.8g/d for the first week. Our test for glucose-6-phosphate dehydrogenase was normal. Clarithromycin was changed to sulfamethoxazole. The treatment of SLE, maintenance of prednisone 5mg/d, MMF 0.75g/d, hydroxychloroquine sulfate 0.2g/d. After about one month of therapy, the reexamination of chest computed tomography showed that the pneumonia was improved (Figure 1c and d). The patient is still under follow-up.