The goal of this clinical trial is to learn whether a study drug called Compound Betamethasone (also known as Diprospan) works to treat pulmonary sarcoidosis in people with early-stage disease (stage I or II). It will also learn about its safety compared to the standard treatment, prednisone.

The main questions it aims to answer are:

• How much does the study drug improve lung function (measured by a test called FVC%) after 24 weeks of treatment?
• How does it compare to prednisone in controlling symptoms, reducing chest lymph node swelling, and preventing relapse? Researchers will compare Compound Betamethasone injections (given once every 4 weeks) to prednisone pills (taken daily with a gradual dose reduction).

Participants will:

• Receive either the study drug injection or prednisone pills for 24 weeks
• Visit the clinic for checkups and lung function tests at weeks 6, 12, and 24
• Have chest CT scans and blood tests to monitor their condition and any side effects
• Be followed up for additional 24 weeks (up to week 48) to see if the disease comes back after treatment stops

Inclusion Criteria:

• Age ≥ 18 years.
• Diagnosed within the past 3 months with stage I-II (based on chest CT) treatment-naive pulmonary sarcoidosis, meeting the following: A. Histopathological diagnosis of sarcoidosis via tissue biopsy (bronchial mucosa, intrathoracic lymph nodes, lung, pleura, etc.) obtained during bronchoscopy; B. Chest HRCT showing mediastinal and hilar lymphadenopathy, with or without pulmonary infiltrates (nodules, patchy opacities, ground-glass opacities, etc.); C. CT stage confirmed independently by at least two experts in the field (among three experts reviewing the chest HRCT images).
• Requiring systemic glucocorticoid therapy.
• Able to complete scheduled follow-up visits.
• Patient and family members understand the study protocol, are willing to participate in this study, and are able to provide written informed consent.

Exclusion Criteria:

• Patient or family members are unable to understand the conditions and objectives of this study, or are unable to provide informed consent.
• Subjects who cannot comply with the follow-up schedule as required by the protocol.
• Presence of other serious diseases that, in the investigator's judgment, may affect patient safety or compliance.
• Any significant clinical or laboratory abnormalities that, in the investigator's judgment, may affect safety evaluation.
• Pregnant or breastfeeding women, or patients who cannot use effective contraception during the study period and within 3 months after the study ends.
• Active malignancy requiring treatment (surgery, medical therapy, or radiotherapy).
• Hypersensitivity to Diprospan (Compound Betamethasone) or prednisone.