Cyclophosphamide is appropriate for this patient who has interstitial lung disease (ILD) associated with diffuse cutaneous systemic sclerosis (DcSSc). This patient with DcSSc presents with dyspnea, decreased exercise tolerance, and characteristic Velcro-like crackles. These clinical findings are strongly suggestive of ILD and are supported by the imaging studies and confirmed by open lung biopsy. Patients with systemic sclerosis who have active inflammatory lung disease may be treated with immunosuppressive agents. Cyclophosphamide is the only treatment shown to have some benefit in patients with ILD associated with DcSSc. Cyclophosphamide given orally or intravenously for 1 year provides modest benefit. Although it has shown limited clinical improvement, it is the only evidence-based therapy and is therefore appropriate. High-dose glucocorticoids are frequently used in these patients but are of unclear benefit and may precipitate scleroderma renal crisis; therefore, if used, low doses are typically recommended by experts. Azathioprine may have a role as maintenance therapy.

Agents such as D-penicillamine or methotrexate have not been shown to be beneficial in these patients and should not be used to treat ILD.

Biologic agents, including tumor necrosis factor α inhibitors such as infliximab, have not been shown to have therapeutic benefit in ILD or systemic sclerosis and should not be used in this patient.