Localized Tracheobronchial Relapsing Polychondritis With Positive matrilin-1 Staining
Relapsing polychondritis (RPC) is a rare progressive autoimmune disease that causes inflammation in the cartilage of multiple organs, with tracheobronchial involvement appearing in nearly half of all cases. Localized tracheobronchial RPC is rarer and has unknown pathogenesis.
Matrilin-1 is a non-collagenous cartilage matrix protein. In animal models, it has been suggested to be a potent autoantigen that induces the airway disease of RPC, but the expression of matrilin-1 in tracheobronchial tissue in humans is unclear. In this case report, the authors examine the expression of matrilin-1 in the tracheal and auricular tissues in a localized tracheobronchial RPC patient.
The 62-year-old patient had systemic sclerosis and presented to the authors institution with cough and dyspnea on exertion. A lung function test showed an expiratory flow limitation and chest CT scan showed diffuse thickness from the trachea to the bronchiole. An endobronchial ultrasonography showed thickness in the fourth-marginal echo layer suggesting inflammation of the cartilage but a tracheal biopsy showed no specific findings
Inflammatory cell infiltration with destruction of the cartilage was found during the subsequent surgical tracheal biopsies. Auricular and nasal deformity was not detected, except for a tracheobronchial lesion.
The patient was diagnosed with localized tracheobronchial RPC.
The patient’s expression level of matrilin-1 in a tracheal and auricular specimen were evaluated and Immunohistochemical staining with anti-matrilin-1 antibody showed matrilin-1 in the tracheal but not in the auricular cartilage.
Makiguchi T, Koarai A, Inoue C, et al. A case of localized tracheobronchial relapsing polychondritis with positive matrilin-1 staining. BMC Rheumatol. 2020. eCollection 2020. DOI: 10.1186/s41927-019-0103-6.