Histological and Immunohistochemical Insights into Disc Perforation in the Temporomandibular Joint: A Case Report

Abstract

Background/Objectives: Anterior disc displacement without reduction (ADDwoR) is a temporomandibular joint (TMJ) disorder characterized by progressive dysfunction and potential complications. Persistent displacement leads to abnormal mechanical stress, predisposing the TMJ disc to structural degeneration, including perforation. This case report aimed to examine the histological and immunofluorescence characteristics of perforated disc tissue to elucidate the mechanisms contributing to its pathology. Methods: A 50-year-old patient with bilateral ADDwoR and disc perforation underwent functional arthroplasty. Tissue samples from the perforated disc were histologically analyzed using hematoxylin-eosin and Azan Mallory staining. Immunofluorescence was performed to assess the expression of collagen type I, fibrillin-1, matrix metalloproteinases (MMPs)-3 and -9, and cluster of differentiation 68 (CD68). Results: Histological analysis revealed disorganized collagen fibres and fibro-chondrocyte cell predominance in the perilesional zone, accompanied by vascular proliferation. Adjacent tissue to perforation exhibited normal fibrous organization. Immunofluorescence showed reduced collagen type I and fibrillin-1 patterns in the perilesional area, indicating an alteration in the fibrillar component of the extracellular matrix (ECM). Increased expression of MMP-3 and MMP-9, as well as elevated numbers of CD68-positive macrophages, suggested active ECM degradation and inflammation localized to the perforation site. Conclusions: This case report underscores the critical role of biomechanical stress and inflammation in disc perforation. Decreased ECM integrity, driven by altered collagen and fibrillin composition, as well as heightened MMP activity, compromises the disc's capacity to absorb and distribute mechanical loads. These findings advance our understanding of TMJ pathophysiology, emphasizing the need for therapeutic approaches that target both biomechanical stabilization and inflammation.

Keywords: ECM degeneration; anterior disc displacement; biomechanical stress; disc perforation; temporomandibular joint disorders.

Figure 1

Proton density (PD)-weighted magnetic resonance imaging (MRI) of the right and left TMJs in closed and open mouth positions. (A–D) The MRIs of both TMJs show anterior disc dislocation without reduction. (A,C) In the closed position (maximum intercuspal), the intermediate zone of the disc is situated anterior to the condylar head, with the posterior part located anterior to the 11:30 position. (B,D) The intermediate zone maintains its anterior position relative to the condylar head in the open position.

Figure 2

Representative surgical steps of the functional arthroplasty procedure performed on the left TMJ. (A) Pre-auricular retro-tragal incision exposing the superficial and deep temporalis fascia. (B) Detachment of the parotid gland from the tragus cartilage and TMJ capsule. (C) Identification of the superficial temporal artery and vein. (D) Ligation and interruption of the superficial temporal artery and vein. (E) Exposure of the joint capsule by blunt dissection and identification of the lateral ligament insertion on the condyle. (F) Incision of the lateral ligament to access the inferior compartment. (G) Recapture of the anteriorly displaced disc. (H) Stabilization of the disc position using anchor screw discopexy and lateral ligament. (I) Deep plane sutures. (J) Skin sutures.

Figure 3

(A) Hematoxylin and eosin staining of the TMJ disc (4× magnification). (B) Disorganized collagen fibres are present in the perilesional area, along with numerous vessels (D) (magnification 40×). (C) The healthy disc area, adjacent to the perilesional area, shows thick bundles of collagen running in a parallel manner (magnification 40×).

Figure 4

(A) Azan Mallory staining of TMJ disc (4× magnification). (B) Disorganized collagen fibres are present in the perilesional area indicated by reduced blue staining (40× magnification). (C) The adjacent normal disc area has parallel collagen bundles (40× magnification). (D) Numerous vessels are present in the perilesional region (40× magnification).

Figure 5

Compound panel of immunofluorescence single-localization reactions in perforated and control TMJ discs, using antibodies against fibrillin-1 ((A), green channel) collagen type I (B) in the red channel. The intensity of both fluorescence patterns is significantly reduced in the perilesional area of the perforated disc if compared to the control disc (magnification 20×).

Figure 6

Compound panel of immunofluorescence single-localization reactions in perforated and normal TMJ disc sections, using antibodies against MMP-9 ((A), green channel) and MMP-3 ((B), green channel) and CD68 ((C), red channel). The fluorescence staining patterns for all markers show an increase in the perilesional area of the perforated disc if compared to the control (magnification 20×).