CASO CLÍNICO

 

Synovial chondromatosis of the temporomandibular joint

Condromatosis sinovial de la articulación temporomandibular

 

 

P. Quirós Alvarez¹, F. García Marín¹, M. Burgueño García², R. Vázquez Carnero³

¹ Cirujano Oral y Maxilofacial. Práctica Privada. Madrid.
² Cirujano Oral y Maxilofacial. Servicio de Cirugía Oral y Maxilofacial. Hospital Universitario La Paz. Madrid.
³ Patólogo. Laboratorio HistioCitoMed. Madrid, España.

Dirección para correspondencia

 

 

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ABSTRACT

Synovial chondromatosis very rarely affects the TMJ. It is a metaplastic disorder of the synovial tissue that usually produces intra-articular loose bodies, or chondromas. It has variable clinical features and the symptoms are unspecific. Examination by means of magnetic resonance imaging and arthroscopic observation are the diagnostic techniques of choice. Treatment consists in the removal the loose bodies and partial synovectomy. Occasionally the skull has been destroyed and the middle cranial fossa invaded. There are cases of malignant transformation to chondrosarcoma. A long-term follow up is necessary. We describe a case with incipient intracranial extension.

Key words: Synovial chondromatosis; Intracranial extension; Treatment; Follow-up.

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RESUMEN

La afectación de la ATM por una condromatosis sinovial es un hecho muy poco frecuente. Trastorno metaplásico del tejido sinovial, suele producir cuerpos libres, condromas, intraarticulares. Tiene una clínica variable y muy inespecífica. Las pruebas diagnósticas de elección son la RM y la artroscopia. La retirada de cuerpos libres y sinovectomía parcial suele ser terapéutica. Ocasionalmente puede destruir la base del cráneo y extenderse intracranealmente. Se han descrito casos de malignización secundaria. Es necesario el seguimiento a largo plazo del paciente. Presentamos un caso con osteolisis incipiente de la fosa cerebral media.

Palabras clave: Condromatosis sinovial; Extensión intracraneal; Tratamiento; Seguimiento.

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Introduction

Synovial chondromatosis (SC) of the temporomandibular joint (TMJ) is a very rare condition. It develops as a result of chondrometaplasia of the subintimal layer of the synovium. Multiple cartilaginous nodules are formed that break off into the joint space. In most cases the process is limited to this space, but on occasions the joint capsule becomes distended, protruding towards the parotid region or skull base. Aggressive behavior has been described with erosion of the temporal bone and intracranial extension.

 

Case report

Female, forty-four years old, attended our department as a result of limited oral aperture that was progressive, and a preauricular tumorlike mass on the left side, which had been developing for years. She had no medical history of interest.

The examination revealed a tumor-like mass that measured approximately 2x2 cm, with an elastic consistency, that was fixed and non-tender (Fig. 1). Oral aperture of 30 mm produced slight joint crepitation with laterodeviation towards the left. The examination of the parotid, facial and cranial nerves, and the intraoral and cervical examination were unremarkable.

With regard to the imaging studies, the panoramic radiography showed a condyle that was slightly irregular compared with the contralateral side (Fig. 2).

The CT scan showed a precondyloid hypodense lesion, measuring 18.4 mm by 31.7 mm. It extended medially towards the base of the external wing of the pterygoid process and the floor of the middle cranial fossa was partially eroded (Fig. 3).

MRI showed considerable distension of the joint capsule anteriorly, along the margins of the mass (Fig. 4).

Its interior was hyperintense and compatible with exudate. There were multiple hypointense signals with variable dimensions, and with a similar density to meniscus or joint fibrocartilage (Fig. 5).

With a presumed diagnosis of a tumor-like mass originating from a joint, compatible with synovial chondromatosis, the lesion was approached by means of a preauricular incision. The joint capsule, which was very distended purplish and hyperemic, was exposed. On opening the capsule, synovial tissue protruded that was thick, inflamed and friable. Once the joint space had been exposed, multiple loose bodies appeared, more than 40, that were whitish and of irregular shapes and sizes and with a stony consistency. Some emerged spontaneously, particularly the smaller ones, and the rest were removed with instruments (Figs. 6 and 7).

Following condylar distraction and extensive lavage, no further intra-articular loose bodies were observed, and the stretched capsule was dissected in the median plane.

The capsular excess and visible synovial membrane were resected, and no metaplastic changes were observed macroscopically. The meniscus, which was moderately deformed and anteriorly luxated, was sutured to the retrodiscal tissue. The capsule was closed, and aspiration drainage was placed before closing the wound. There were no incidents during the postoperative period. The pathological examination showed multiple nodules of hyaline cartilage that were covered by synovial epithelium (Fig. 8). The synovial membrane showed signs of inflammation, but with no chondrometaplasia. The patient started physiotherapy promptly, and six months later she was asymptomatic. Her oral aperture was 37 mm.

 

Discussion

Synovial chondromatosis (SC) tends to affect the larger joints of the axial skeleton. It is more common in women, in right-sided joints.^3,4 It is diagnosed later on in life, during the fourth and fifth decades, than in the remaining locations³ and exceptionally it can be bilateral.¹ While macro- and microtraumatism have been implicated,³ its etiology is unknown.

Two types have been identified; primary SC is a chondral metaplasia of mesenchymal tissue remains at a subsynovial level. It has three stages:² Stage one is a process that is limited to the synovial membrane, and hyperemic and edematous papillae are formed. In stage two, synovial metaplasia occurs. There are intra-articular loose particles and active chondrocytes. Stage three consists of loose particles with normal synovial membrane.

Secondary SC is much more common.¹⁷ It tends to be due to arthroscopic or traumatic changes as a result of which osteochondral fragments are released into the joint space.

As the disease develops, cartilaginous nodules may appear and become calcified, the synovial tissue thickens and degenerative changes appear in the joint surfaces.²

The most frequent symptoms are:³ pain, inflammation, limited joint movement, crepitation, clicks. As the clinical symptoms are unspecific and benign, the diagnosis is often delayed.

The differential diagnosis takes into account: muscular processes, inflammatory and traumatic arthropathies, temporomandibular dysfunction, ankylosis and infections such as tuberculosis. If there is posterior involvement, it may appear to be a lesion of the middle or external ear; anterior and lateral extension may be suggestive of a parotid tumor.¹⁶ Histologically it has been confused with a benign mixed tumor.¹² On occasions the coexistence of SC has been described with villonodular synovitis, condylar hyperplasia and other pathologies, ³ which makes diagnosis difficult.

Conventional radiology is negative in 24-57% of cases.³ Only if the loose bodies are calcified will they be visible. The indirect signs are unspecific: bone erosion, sclerosis, joint space increase.

The CT scan will show the size, form and location of the loose bodies, although the modality of choice is MRI, as a differential diagnosis can be carried out with other synovial proliferative disorders, the size of the lesion is shown, the chondromas are located and the synovial origin of the lesion is confirmed.^11,12 It is particularly useful when extracranial extension is suspected in order to evaluate the proximity and involvement of the duramater and for planning the surgery.

Adequate evaluation by means of a CAT scan or MRI can avoid unnecessary parotidectomies and condylectomies.¹⁰

The best diagnostic procedure is the arthroscopy. Intraarticular loose bodies with a chondroid nature will be shown, as well as possible areas of synovial metaplasia.⁵ The number of loose bodies may be suggestive of the diagnosis.¹⁴ Most patients with primary SC have more than ten loose bodies, while the remaining pathologies have less than three.

Microscopically islands of hyaline cartilage can be appreciated in the connective tissue of the subintimal synovial layer, that protrude into the synovial membrane or that have come away from the joint cavity.⁴ These nodules can become calcified and they may undergo enchondral ossification, in an irregular and patchy manner, normally from the outside towards the center.⁷ The chondrocytes are distributed in groups in an irregular manner throughout the nodule (Fig. 8), and they often show atypical features.³ The secondary forms have nodules of a larger size with a more irregular surface. Once sectioned, a central area tends to appear with the osteoarticular fragment that started the process. It is less cellular and more uniform and, histologically, it is more benign. The calcifications are arranged in bands or they may have a concentric shape and form rings.

The most important differential diagnosis should be made with synovial chondrosarcoma. It has a similar histology but it is not made up of cellular clumps. Signs of aggressive bone infiltration can be seen together with a permeative pattern.⁴ Some cases of malignant transformation to chondrosarcoma have been described in the TMJ. This should be suspected following SC treatment when there are multiple relapses in a short space of time.¹³

Treatment is based on surgical examination, either open or arthroscopic, and the removal of the loose bodies together with a partial synovectomy of the inflamed and metaplastic areas.⁵ The arthroscopic approach is the method of choice if the imaging studies show that only the upper space has been affected, if there is no extra-articular involvement, and if the size of the nodules is less than 2-3 mm. The chondromas can be removed through the instrument cannula and the affected synovial areas should be abraded. However, large sized loose bodies cannot be removed in this way, and there may be more frequent cases of relapse.^3,7,8

If there are extra-articular nodules in areas that are difficult to access, a conservative view can be taken. If there is no synovial involvement, they can remain asymptomatic and not change in size for years.⁶

There are patients with a long history of SC that is locally destructive, with erosion of the glenoid or infratemporal fossae and with extension towards the middle cranial fossa. Although it may remain extradural, massive bone erosion has been described, with displacement of structures and paralysis of the facial nerve.^7,9,11,12,15 In this situation the differential diagnosis should be carried out with neoplastic processes. Local control should be ensured, together with complete exeresis enabling posterior analysis so as to rule out malignancy, and in order to avoid the risk of degeneration of the residual lesion.^11,12

Relapses have been described in up to 30% of cases, possibly as a result of incomplete resection of the metaplastic synovium, while some authors have not found any differences between open or arthroscopic surgery.^4,14 Only will the histopathologic examination of the synovial membrane determine if the condition has stabilized or not, as this cannot be assumed from the appearance of the joint or the particles.⁷

The latest studies are investigating the possibility that SC may be secondary to a neoplastic clonal proliferation.¹²

A periodic, indefinite following of the patient is advised.

 

 

Dirección para correspondencia:
Dr. Pedro Quiros Alvarez
Avda. Betanzos, 60 3ºD
28034 Madrid, España.
Email: pquirss@hormail.com

Recibido: 12.07.2005
Aceptado: 23.01.2006

 

 

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