Chondroblastoma is a rare and benign bone tumor that can occur in the craniofacial region. It may be difficult to diagnose using imaging alone; histological analyses and even immunohistochemical analyses are often required. This article reports on a rare case of chondroblastoma of the temporomandibular joint. Its diagnosis was hindered by its similarity to other tumors in both imaging exams and histological analyses. It was definitively treated through the total excision of the tumor.
This is a rare case of an extra-osseous chondroblastoma in the temporomandibular joint region.
It draws attention to a clinical diagnosis that, often, can not be done only by means of imaging and histopathological examinations.
Rare case of a chondroblastoma in the temporomandibular joint region, requiring an immunohistochemical analysis.
Chondroblastoma was first established in 1931 by Codman, who reported nine cases of a growth that he referred to as “a giant cell chondromatous tumor of the epiphysis” [ ]. In 1942, Jaffe and Lichtenstein distinguished chondroblastoma from giant cell tumors and created the term “benign chondroblastoma.” They hypothesized that this tumor may originate from remains of the fetal chondroid skeleton [ ]. It is a benign cartilaginous neoplasm that represents approximately 1% of all primary tumors affecting the epiphyses of long bones, particularly in the proximal tibia or humerus, as well as in the distal femur. It rarely forms in the region involving the mandibular condyle [ ]. The rarity of this tumor increases exponentially when it is a case of chondroblastoma that is extraosseous and in the region involving the temporomandibular joint (TMJ) [ ]. The following report describes one of the few cases of extraosseous chondroblastoma on the TMJ. It was successfully treated through total excision of the tumor.
A 46-year-old patient reported that 3 years before the discovery of chondroblastoma, he started pain in the left temporomandibular region. As a previous medical history it presented only discoid lupus but already in follow-up with dermatologist, without any history of trauma or surgery or some internal disorder in temporomandibular joint (TMJ). As pre-auricular pains increased in intensity as the days went by, he sought medical treatment. The initial medical management was by means of analgesics for a period of 10 days. The pain subsided and the patient followed without further care.
Two years later, the patient returned with pain that had spread to the left auricle and which was associated with increased volume at the site. He sought care from an otolaryngologist, who ordered an MRI and CT of the region. The MRI revealed prominent bicompartmental joint effusion with thickening and diffuse synovial impregnation by contrast both more prominent to the left side, associated with a clearly defined lesion. The lesion was oval-shaped, surrounded by a hypointense halo sign. The inner portion exhibited a heterogenicity compatible with calcifications with a high signal in sequences sensitive to liquids. The dimensions were 2.1 × 1.0 × 1.7 cm ( Fig. 1a, b, 2a, and 2 b ). In the CT, the lesion seemed internally mixed lateral to the left condylar process and exhibited a discretely hypodense halo ( Fig. 3 ).
The patient was then sent to an oral and maxillofacial surgeon and underwent surgery with general anesthesia on September 29, 2017, to completely excise the lesion ( Fig. 4 a, b, 4c and 4d). The tumor was excised using the preauricular approach due to its dimensions and was then sent for histopathological analysis. The histological analysis revealed areas with chondral calcification, as well as areas that were cartilaginous in nature mixed with synovial tissue with polygonal stromal cells and multinucleated giant cells ( Fig. 5 ). The clinical and histological findings were insufficient to establish a diagnosis, since they did not allow for the exclusion of other, histologically similar tumors such as synovial chondromatosis or pigmented villonodular synovitis with cartilaginous metaplasia. For this reason, an immunohistochemical analysis was performed. It revealed fragments of hypercellular neoplasm with multinucleated giant cells ( Fig. 6 a) and fine linear calcifications surrounding the stromal cells in a “chicken wire” or lace-like pattern. These fragments were associated with the formation of immature chondroid material ( Fig. 6 b). An immunohistochemical stain for S-100 protein ( Fig. 6 c) was positive in neoplastic cells inside and outside the cartilaginous matrix, showing its chondroid differentiation, making the diagnosis compatible with chondroblastoma.