Systemic sclerosis complicated by azathioprine-induced iatrogenic immunodeficiency-associated lymphoproliferative disorder: A case report.

Lymphoproliferative disorders are rare complications in patients with autoimmune diseases who are receiving immunosuppressive therapy. This case report describes a 74-year-old man with diffuse cutaneous systemic sclerosis (SSc), anti-RNA polymerase III antibodies, and interstitial pneumonia. The patient's condition initially improved with prednisolone and intravenous cyclophosphamide, followed by maintenance therapy with azathioprine (AZA), nintedanib, and macitentan for pulmonary hypertension. Thirty months after initiating AZA, the patient developed nodules and ulcers in the left lower jaw and philtrum. Skin biopsy confirmed diffuse large B-cell lymphoma. Discontinuation of AZA led to the resolution of the ulcers, and no other lesions were found. This case highlights the risk of iatrogenic immunodeficiency-associated lymphoproliferative disorders in patients with SSc, particularly in those with anti-RNA polymerase III antibodies, who are known to have an increased risk of malignancy. Although methotrexate-associated lymphoproliferative disorders are well documented in patients with rheumatoid arthritis, this is the first reported case of AZA-associated lymphoproliferative disorder in SSc. These findings emphasise the importance of close monitoring of malignancies, including lymphoproliferative disorders, in patients with SSc undergoing immunosuppressive therapy.