Granulomatosis with polyangiitis (GPA) is a systemic disease characterized by necrotizing, granulomatous vasculitis of the upper and lower respiratory tracts and glomerulonephritis, and is classified as a classical or limited form. The classical form of GPA demonstrates the involvement of the upper respiratory tract, sinuses, lungs and kidneys, whereas the limited form is characterized by the lack of the renal involvement with female predominance. On the other hand, mixed connective tissue disease (MCTD) shows the clinical and laboratorial features of systemic lupus erythematosus, systemic sclerosis and polymyositis, along with high titers of anti-ribonucleoprotein antibodies and is characterized by good response to corticosteroid therapy and favorable prognosis. We herein report a patient with a history of MCTD that developed into a limited form of GPA (pulmonary-limited GPA). A 39-year-old woman suffered from persistent cough, left back pain and appetite loss. At 21 years of age she was diagnosed with MCTD, but the persistent administration of prednisolone or immunosuppressants was not needed. On admission, high-resolution chest computed tomography showed bilateral, multiple, poorly circumscribed nodules and masses, some of which showed cavitation. A surgical lung biopsy demonstrated granulomas with vasculitis surrounding the necrotic lesions. She was diagnosed with pulmonary-limited GPA. In conclusion, we should recognize that GPA may develop during the disease course of MCTD even after prolonged disease remission. To prevent progression to an irreversible state, physicians should consider a surgical lung biopsy for the diagnosis in patients suspected of having pulmonary-limited GPA.
Keywords: anti-neutrophil cytoplasmic antibody-associated vasculitis; granulomatosis with polyangiitis; human leukocyte antigen genotype; mixed connective tissue disease; shared autoimmunity.