Uncommon Localization of Tenosynovial Giant Cell Tumor in the Coracoclavicular Ligament: Diagnostic Challenges

Introduction

Tenosynovial giant cell tumors (TGCTs), also referred to by various historical or alternative names, such as pigmented villous nodular synovitis, benign synovioma, xanthogranuloma, and limited nodular tenosynovitis, are a group of proliferative, inflammatory, and typically benign neoplastic diseases originating in the synovium of the joints, bursae, and tendon sheaths [1,2]. TGCTs, or pigmented villous nodular synovitis, often occur in a single joint, with the highest incidence in the knee joint, which is also the most likely site for recurrence [3]. TGCTs are classified into 2 subtypes: localized TGCT (L-TGCT), characterized by single nodules, and diffuse TGCT (D-TGCT), which involves multiple nodules [3,4]. L-TGCT is commonly found in the digits (85% of cases) and wrists, while D-TGCT is commonly seen in large joints, including the knee (75% of cases), hip, and ankle, is more aggressive and destructive, and can develop into a malignant TGCT [1,4]. The peak incidence of TGCTs occurs between 30 and 40 years of age, and it is more common in women than in men [5]. At present, of the atypically located TGCTs reported in the literature, there are no reports of a TGCT occurring in the coracoclavicular ligament. In this article, we report a rare case of coracoclavicular ligament TGCT, which can provide ideas for clinical diagnosis of the tumors, improve clinical diagnosis level, and reduce missed diagnosis and misdiagnosis.

Case Report

A 16-year-old female patient visited the First Affiliated Hospital of Guangxi Medical University on January 14, 2023 for “right shoulder pain and limitation of movement for 1 month, aggravated for 1 week”. Specialized physical examination on admission revealed the right shoulder joint active range of motion was limited to 60° of abduction, 120° of forward elevation, and 30° of posterior extension, beyond which the pain increased. There were no restrictions in passive range of motion. Although pain was present, it was less severe with passive than with active motion. In active and passive range of motion, the patient did not present with symptoms of brachial plexus compression, such as numbness, skin sensory abnormalities, and reflex pain, in the right upper extremity. At the same time, the patient’s neurological examination showed no abnormalities (no weakening or disappearance of the right biceps reflex and triceps reflex). It can therefore be concluded that there was no possibility of tumor compression of the surrounding nerves. The pain did not change with certain positions. A mass was palpable between the coracoid process and the clavicle, with localized tenderness. It is rare to observe calcification on imaging of TGCT [1,3]. Therefore, it is easy to overlook TGCT when a mass with calcified margins is found on imaging. Computed tomography (CT) identified a round soft-tissue density lesion in the soft tissue around the right coracoid process, with a ring calcification lesion at the edge clearly demarcated with adjacent structures, about 2.8×2.5×2.1 cm in size. The adjacent muscles were compressed and displaced (Figure 1). Lesions were identified above the right coracoid process. Magnetic resonance imaging (MRI) with contrast enhancement (Figure 2) revealed nodular lesions with equisignal on T1-weighted images and mixed signal intensity on T2-weighted images. The nodules measured approximately 3.2×2.5×1.5 cm. The lesion boundaries were clear. Additionally, the deltoid muscle was compressed. The enhanced scan showed obvious uneven enhancement of the lesions, and a small nodular non-enhanced area was seen inside. The conclusion was that lesions were identified above the right coracoid process.

Surgical treatment (Figure 3) was performed with the patient under general anesthesia and in the supine position. A transverse incision of about 4 cm was made between the right coracoid process and the clavicle. The skin and subcutaneous tissue were incised, the deep fascia was incised longitudinally, and the clavicular part of the deltoid muscle tract was pulled apart. The mass was fully exposed. The mass was located on the coracoclavicular ligament, with a clear boundary, obvious envelope, and tough texture. The tumor was bluntly removed along the edge of the tumor envelope, was clamped and lifted, and was removed completely; we were careful to avoid damage to the coracoclavicular ligament, blood vessels, and nerves. The wound was closed in layers and dressed. Intraoperative gross pathology revealed an intraoperative mass measuring about 3×2×1.5 cm in front of the right coracoclavicular ligament. The color was gray-red and yellow-white, with a clear border, obvious envelope, and tough texture. Postoperative pathology revealed a visual appearance of a grayish-brown tissue, 3.5×2×1.5 cm in size; the section was grayish-white and solid, with partial hardness. Microscopically, there was monocytoid fibrous tissue hyperplasia and partial granulation tissue hyperplasia, accompanied by a large number of acute and chronic inflammatory cell infiltrates and evidence of old bleeding. Numerous multinucleated giant cells were observed, along with hemosiderosis, scattered osteoclastic giant cells, reactive bone, and chondrogenous bone (Figure 4). The pathological diagnosis was TGCT. No special staining results were found for Ag and PAS. At the 6-month (Figure 5) and 1-year (Figure 6) postoperative follow-ups, the patient’s CT examinations showed no evidence of tumor recurrence in the original lesion area and no signs of calcified margins.

At the 2-year follow-up after surgery, the patient’s MRI examination also showed no signs of soft tissue tumor recurrence on T1- and T2-weighted images (Figure 7). Because the surgeon was able to remove the tumor completely during the surgery, the patient continued to show no signs of tumor recurrence, even though she did not undergo radiotherapy or other adjunctive treatment after the surgery. In addition, the patient’s post-surgical shoulder function improved dramatically, compared with the pre-operative period (including no shoulder pain or limitation range of motion), and returned to a level consistent with the healthy side.

Discussion

The pathogenesis and etiology of TGCTs remain unclear and are still debated in the academic community. The more widely accepted pathogenetic theories currently include chronic inflammation, lipid metabolism disorders, and neoplastic (tumor-related) origins [3,6,7]. The disease can present with swelling, pain, limited joint movement, and even stiffness. Due to the lack of specific and typical clinical manifestations, the onset of the disease is insidious, the progression is slow, and it is easily misdiagnosed or overlooked. These affects the timely treatment. Most cases, such as that presented in this report, are detected and diagnosed during hospital visits for joint pain and mobility problems. The present case occurred in an atypical location, which made the diagnosis and treatment of the disease challenging. Similarly, Liu and Liu [8] reported a case of TGCT occurring in the retropharynx, and Suzuki et al [9] reported a case of D-TGCT occurring in the temporomandibular joint and extending to the external auditory canal. Sakamoto et al [10] reported a case of TGCT occurring in the elbow joint of a child, and Tsui et al [11] reported a case of cervical TGCT occurring in the pediatric atlantoaxial joint. Accurate diagnosis of these TCGTs on the basis of clinical presentation is very difficult because they are atypical in location and symptoms. In this context, it is critical to perform thorough imaging, including X-ray, CT, and MRI. This is essential for the diagnosis of TGCT, especially when it occurs in atypical locations. The imaging features of X-ray and CT are generally consistent. The lesion typically appears as a soft-tissue mass that is slightly denser than muscle. The affected area can show a well-defined sclerotic margin, although most margins do not exhibit signs of calcification or ossification [1,3]. Limited cases usually have clear borders and no bone erosion, while some diffuse and recurrent cases have indistinct borders with compressive erosive changes in the adjacent bone [12–14]. The present case is a rare case of marginal calcification.

MRI is currently the best method to evaluate the size of the tumor and the severity of the invasion of adjacent joints and tendon sheath space. It can show features including synovial hyperplasia, joint effusion, bone erosion, and hemosiderin deposition. TGCTs can manifest as equal or low signal on T1-weighted imaging and mixed signal on T2-weighted imaging, which is associated with the presence of hemosiderin and collagen fibers. When the lesion contains more hemosiderin, T1-weighted imaging and T2-weighted imaging can show a characteristic intralesional, localized, or diffuse low signal [3]. When the lesion has a low hemosiderin content and is dominated by collagen fibers, T1- and T2-weighted imaging can show the same or slightly higher signal than skeletal muscle [15]. It has been shown that deposition of a mixture of hemosiderin and villous nodular soft tissue masses is a characteristic manifestation of TGCTs on MRI images [16,17]. The TGCT is rich in capillaries, and the solid part of the lesion shows uneven enhancement on contrast-enhanced scan. The imaging features of the present case were basically consistent with the above description. TGCTs can be considered when such imaging findings and patient history are encountered clinically, and the final diagnosis is based on pathological examination.

In gross pathology, there is great variation in the presentation of TGCTs. They are mostly located in the tendon sheath, close to the tendon, and can appear yellowish, grayish-yellow, or yellowish-brown. Most are softer in texture, and the peritendinous membrane is often fused with the tendon sheath. Microscopically, the pathology mainly consists of 3 components: large synovial-like mononuclear cells, small mononuclear histiocytes, and osteoclast-like giant cells. The cell types are highly variable, including foam cells with small nuclei and lipid-like bodies within the cytoplasm. Hemosiderin deposits are present, accompanied by a large number of multinucleated giant cell reactions. The interstitium contains varying degrees of collagen-forming fibrous tissue [1,8,18]. The pathological findings of the present case were consistent with those described above. From combining imaging features, clinical manifestations, and pathological findings, the case was diagnosed as an L-TGCT.

Currently, the first choice of treatment of either typical or atypical TGCTs is surgical removal of the tumor tissue; however, the main disadvantage of surgical resection is recurrence of the TGCT and destruction of joints [1,3,7–11,16]. L-TGCTs can be treated by complete resection in most cases, whereas D-TGCTs require arthroscopic or open resection [19–21]. In addition to surgical treatment, there is postoperative treatment with radiotherapy, which has been shown to be effective in preventing recurrence and significantly improving joint function [2–4,6,22,23]. For example, Lubis et al [7] used adjuvant radiotherapy in the treatment of recurrent D-TGCT of the knee, and Jerome et al [24] reported cases of combined adjuvant radiotherapy after removal of TGCT of the thumb. In both cases, good treatment results were achieved. There are also pharmacologic treatments for multiple relapses that are not amenable to surgical treatment, including the use of small-molecule tyrosine kinase inhibitors, such as pexidartinib [25]. The U.S. Food and Drug Association approved pexidartinib in August 2019 for the treatment of adult patients with TGCT who have serious comorbidities that cannot be treated surgically [26]. Gelderblon et al demonstrated the long-term efficacy and tolerability of long-term treatment with pexidartinib for TGCTs in a study of 130 patients with extended follow-up [27]. Patients with TGCTs who are not suitable for surgical resection have a good prognosis with the use of CSF1R inhibitors. Complications of TGCTs include recurrence, joint stiffness, and even severe joint destruction. L-TGCTs are predominantly localized, and there are reports of good clinical outcomes and low recurrence rates with surgical treatment [8,14]. The recurrence rate after surgery is 10% to 20%, and even if recurrence occurs, reoperation is still effective [2]. D-TGCTs involve difficult surgical issues, local control is uncertain, and recurrence rates range between 21% and 50%. Between 27% and 62% of patients are free of local recurrence at 5 years [8,28]. In rare cases, malignant changes and metastasis can occur, For example, Shaik et al reported a case of TGCT with development of distant metastases to the lung and pleura [1,6,16]. However, clinical cases of malignant TGCTs have also been reported [16,29–31]. Due to the special and rare location of the lesion in the present case, we selected surgery to remove the tumor. No drugs, radiation, or chemotherapy were given after surgical resection. Imaging examination 6 months, 1 year, and 2 years after surgery showed no recurrence of the disease, the patient’s shoulder joint symptoms improved significantly, and the function returned to normal, demonstrating that the outcome of the tumor removal surgery in our case was satisfactory. To definitively assess the prognosis of the patient, the shoulder joint should be examined using MRI and CT, to observe for tumor recurrence and for compression and erosion of nearby bone. The patient should be asked about recurring symptoms.

Conclusions

TGCTs rarely occur in the shoulder joint, and even more rarely in the coracoclavicular ligament. This report reminds doctors that MRI can help identify these tumors more clearly. When characteristic features appear on MRI or CT – such as isointense signals on T1-weighted images and mixed signals on T2-weighted images on MRI, along with a circumferential calcified lesion at the margin on CT – we should consider the possibility of TGCT. The characteristic imaging findings of TGCT are helpful for early diagnosis and treatment, which can improve the prognosis of the disease and reduce the risk of tumor recurrence or metastasis. Additionally, long-term postoperative follow-up is essential, as it is critical for monitoring recurrence, evaluating treatment efficacy, and enabling early intervention. Therefore, we hope this case report can offer insights for the diagnosis and treatment of TGCT in clinical practice, helping to improve diagnostic accuracy, reduce missed and incorrect diagnoses, ensure patients receive timely and appropriate treatment, and ultimately enhance their quality of life.