A case of localized tracheobronchial relapsing polychondritis with positive matrilin-1 staining

Abstract

Background: Relapsing polychondritis (RPC) is a rare progressive autoimmune disease characterized by inflammation in the cartilage of multiple organs. Tracheobronchial involvement appears in nearly half of RPC patients during the course of their disease and represents the main cause of death. Localized tracheobronchial RPC is much rarer, and the pathogenesis remains unclear. Matrilin-1 is a non-collagenous cartilage matrix protein and has been suggested to be a potent autoantigen that induces the airway disease of RPC in animal models. However, the expression of matrilin-1 in tracheobronchial tissue in human remains unclear. Therefore, we examined the expression of matrilin-1 in the tracheal and auricular tissues in a localized tracheobronchial RPC patient.

Case presentation: A 62-year-old man with systemic sclerosis presented with cough and dyspnea on exertion. The lung function test showed an expiratory flow limitation and chest computed tomography showed diffuse thickness from the trachea to the bronchiole. No other tests showed abnormal findings. To evaluate further, bronchoscopy was performed and endobronchial ultrasonography showed thickness in the fourth-marginal echo layer suggesting inflammation of the cartilage. However, the tracheal biopsy showed no specific findings. The subsequent surgical tracheal biopsies showed inflammatory cell infiltration with destruction of the cartilage. Neither auricular nor nasal deformity, except for a tracheobronchial lesion, was detected. Biopsy from the left auricular cartilage also did not show any inflammatory changes. Finally, we diagnosed the patient with localized tracheobronchial RPC. To address the hypothesis that autoimmunity against matrilin-1 is involved in the pathogenesis of localized tracheobronchial RPC, we evaluated the expression level of matrilin-1 in a tracheal and auricular specimen from this patient. Immunohistochemical staining with anti-matrilin-1 antibody showed matrilin-1 in the tracheal but not in the auricular cartilage.

Conclusions: We first demonstrated the expression of matrilin-1 in tracheal but not in auricular cartilage in a localized tracheobronchial RPC patient. This result supports the possibility that matrilin-1 is involved in the pathogenesis of localized tracheobronchial RPC. However, this is only one case report and further observations will be needed to confirm this result.

Keywords: Matrilin-1; Relapsing polychondritis; Tracheobronchial.

Fig. 1

Lung function test during the clinical course. Lung function test 7 months before (a) and at the time of consultation (b). Seven months before the consultation, the flow volume curve was almost normal except for a slight downward convex in the latter half of the expiratory phase (a). At the time of the consultation, both peak expiratory flow (PEF) and forced expiratory flow in 1 s (FEV₁) were markedly decreased (b)

Fig. 2

Computer tomography (CT) during the clinical course. Thoracic CT 7 months before (a) and at the time of consultation (b). Compared to before the onset, the wall of the trachea to the bronchiole had thickened diffusely

Fig. 3

Imaging findings of bronchoscopy. a Bronchoscopy shows narrowing of the trachea and the straight pattern on the membranous portion with disappearance of the tracheal cartilage. b Endobronchial ultrasonography (EBUS) of trachea shows thickening of the cartilage layer

Fig. 4

Histopathological findings of the surgical biopsy specimen from the trachea. a Histological examination by hematoxylin-eosin staining of the lesion shows infiltration of inflammatory cells with destruction of the cartilage. b-d Immunohistochemical staining of tracheal wall with anti-CD3 (b), anti-CD20 (c), or anti-CD68 (d) antibody. Arrow represents CD3-, CD20- or CD68- positive cells, respectively. Magnifying power is (×100) except for (C) (×200). Asterisks represent tracheal cartilage. Bar, 100 μm

Fig. 5

Immunohistochemical staining of matrilin-1 in the tracheal and auricular specimen. Immunohistochemical staining of tracheal and auricular cartilage with anti-matrilin-1 antibody. Immunoreactions are visualized with 3, 3-diaminobenzidine and counterstained with hematoxylin. Matrilin-1 immunoreactivity (brown, arrow) is detected mainly in the boundary region of the cartilage and some chondrocytes in the trachea (a, c), but not in the auricular tissue (b). Asterisk represents the cartilage. Magnifying power is (×100) both in (a) and (b). High-magnification image (×200) is shown in (c). Bar, 100 μm