Rare association of granulomatosis with polyangiitis with an underdiagnosed spondyloarthritis effectively treated with rituximab: A case-report.

Rationale: Associations of autoimmune diseases are rare but interesting and challenging situations from a diagnostic, pathophysiological, and therapeutic point of view. This article studies a rare association of autoimmune diseases by discussing the pathophysiological hypotheses and an original therapeutic management. The coexistence of antineutrophil cytoplasmic antibody-associated vasculitis and spondyloarthritis has rarely been described.

Patient concerns: We present a patient with inflammatory back pain, stiffness, and enthesopathies followed by pulmonary and ear, nose and throat granulomatous involvement.

Diagnoses: A combination of spondyloarthritis and granulomatosis with polyangiitis, with spinal, enthesopathic, pulmonary, and ear, nose and throat involvement.

Interventions and outcomes: Effective treatment with rituximab both on spondyloarthritis and vasculitis.

Lessons: We discuss the pathogenic, diagnostic, and therapeutic implications of this rare but intriguing association between these 2 inflammatory conditions.