Immunohistochemical characterization of granulomatosis with polyangiitis exhibiting spontaneous regression

Yasuhiro Masuta,¹ Yoriaki Komeda,¹ Ikue Sekai,¹ Akane Hara,¹ Masayuki Kurimoto,¹ Keisuke Yoshikawa,¹ Yasuo Otsuka,¹ Ryutaro Takada,¹ Tomoe Yoshikawa,¹ Ken Kamata,¹ Kosuke Minaga,¹ Osamu Maenishi,² Tomohiro Watanabe,¹ Masatoshi Kudo¹

¹ Department of Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
² Department of Diagnostic Pathology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan

Abstract

Background: Granulomatosis with polyangiitis (GPA) is characterized by granulomatous inflammation, vasculitis, and elevated levels of serum proteinase 3 (PR3)-anti-neutrophil cytoplasmic antibody (PR3-ANCA).
Objective: We tried to characterize immune cells accumulated into the lung lesions of a GPA patient exhibiting spontaneous regression.
Methods: Transbronchial lung biopsy (TBLB) samples were subjected to immunohistochemical analyses.
Results: Multiple lung nodules were detected by CT. TBLB showed granulomatous inflammation and small vessel vasculitis. This case was diagnosed as GPA based on pathological findings and elevation of PR-3 ANCA levels. Spontaneous disappearance of multiple lung nodules was observed in CT. CD3⁺ T cells and CD20⁺ B cells accumulated in the inflammatory lesions surrounding the vessels whereas granulomatous inflammation was mainly comprised of CD3⁺ T cells and CD68⁺ macrophages, but not B cells or myeloperoxidase⁺ neutrophils.
Conclusion: We characterized immune cell compositions of the lung lesions of a patient with GPA exhibiting spontaneous regression.
Key words: Granulomatosis with Polyangiitis, Spontaneous Regression, Lung, Immunohistochemistry, PR3-ANCA