IgG4-associated lung disease with granulomatous lesions: Coexistence of two entities or the spectrum of one disease? Koexistenz zweier Entitäten oder das Spektrum einer Erkrankung?

A 54-year-old patient with a history of pulmonary tuberculosis and occupational exposure to dust in early adulthood presented with symptoms of coughing with sputum, weight loss, occasional night sweats, and thoracic pain. Non-necrotizing granulomatosis in lung and lymph-node biopsies indicated sarcoidosis. Combined immunosuppressive therapy did not lead to an improvement. An atypical lung resectate with fibroinflammatory changes and obliterative endothelialitis may finally lead to the diagnosis of IgG4-associated lung disease with a bronchovascular pattern of involvement. The question discussed here is whether this is a coexistence of IgG4-associated lung disease with sarcoidosis or the spectrum of one disease.