An Unusual Presentation of Giant Cell Tumour of Bone in the Talus: A Case Report and Literature Review

Giant cell tumours (GCTs) of the bone often arise in the long bones while occurrence in smaller bones of the hand and feet is very rare. We report a case of GCT in the talus of a 17-year-old male who presented with a six-month history of worsening pain in his left ankle and loss of function, reducing his ability to walk and participate in sports. Radiographs of the ankle showed bony overgrowth on the head and neck of the talus with cortical breaching. MRI revealed possible extension into soft tissue and bone marrow oedema. CT scan also revealed an aggressive lytic lesion at the head and neck of the talus. He was managed with intralesional curettage and autologous bone grafting with bone harvested from the left knee. There was no evidence of recurrence at the six-month follow-up and the patient was able to walk freely. In conclusion, GCTs of the talus tend to occur in younger and healthier patients and have disastrous consequences if they persist, recur, or metastasize. Given the severe negative impact that GCTs have on a patient’s quality of life, they must be ruled out when investigating any ankle pain or reduced mobility. Current treatment options have produced consistently positive results while novel therapies that enable a faster return to weight bearing and reduce recurrence appear promising.


Introduction
Giant cell tumours (GCTs) of the bone are benign but potentially aggressive tumours more commonly seen in women and arise between the ages of 20 and 40 years [1]. GCTs most commonly occur in the epiphysis of long bones such as the distal femur, proximal tibia, distal radius, and sacrum while GCTs of the tarsal and metatarsal bones are rare, occurring in only 1.5% of cases [2,3]. GCTs present with pain, swelling, and reduced range of motion [1]. GCTs are radiolucent on radiography and can be differentiated from other benign bone lesions using their incomplete sclerotic rim, while on histology, they display numerous giant cells with benign spindle cells [1]. The traditional management of GCTs using intralesional curettage and bone grafting has a 27-60% local recurrence rate in a period ranging from two to 30 years [4]. There is a risk of lung metastases, seen in 1-6% of cases and usually between 18 and 24 months, hence requiring routine chest radiographs [1,5]. We present an unusual presentation of a GCT of the bone in the talus of an adolescent male and review the literature on GCTs presenting in the talus.

Case Presentation
A 17-year-old male presented with a six-month history of worsening pain in his left ankle and foot with increasing loss of function, becoming most severe two months prior. There was an associated reduction in left lower limb muscle bulk. The patient who was fit and active was now struggling to walk and was unable to play sports for the past six months. He complained of poor sleep and a weight loss of 5 kg. His appetite was normal, and he denied any history of trauma, fever, night-time pain, or night sweats. There was also no right ankle pain and no left hip or knee pain. On examination, there was diffuse dorsal-medial-lateral swelling of the left ankle. He had a full range of motion, intact distal neurovascular status and no overlying skin changes, redness or warmth. He was walking with an antalgic gait and was unable to run.
Radiographs of the left ankle showed bony overgrowth on the head and neck region of the talus with cortical breaching (Figure 1). A computed tomography (CT) scan revealed an aggressive 20 mm lytic lesion at the head and neck of the left talus ( Figure 2). Magnetic resonance imaging (MRI) revealed possible extension into soft tissue, a subcortical bone structure of about 1.5 x 1 x 1.2 cm in size, a small defect in the cortical layer and extensive bony oedema ( Figure 3). Apart from neutrophilia at 7.7×10⁹/L, general haematology results, such as haemoglobin, white cell count and erythrocyte sedimentation rate, were normal. Biochemistry results revealed high alkaline phosphatase at 161 IU/L and high calcium at 2.6 mmol/L. Creactive protein and lactate dehydrogenase were normal. A coagulation screen revealed a prothrombin time of 14.2 s. The expertise and guidance of the tertiary-level orthopaedic oncology centre were sought, and the decision was made to proceed with an ultrasound-guided biopsy to rule out osteosarcoma. An orthopaedic consultant specialist in foot and ankle surgery performed the procedure in consultation with the orthopaedic oncology surgical specialist. This was done under aseptic conditions using a 13 gauge x 16 cm bone biopsy needle to access the lytic lesion of the anterior medial talus. Multiple samples were taken directly to histology. Results indicated that the samples received were non-representative of the lesion in question. A supplementary report further stated that there were some fragments of slightly reactive bone and normal articular cartilage. Although the biopsy did not identify any inflammation or tumour, the radiologists reported there was a significant lesion at the time of biopsy, suspected to be a GCT or chondral blastoma. These results thus fell into the 10% of oncological biopsies that are deemed non-conclusive. Based on this finding, the tertiary centre was contacted again and the decision to operate and remove the lesion was made.
A left ankle excisional bone biopsy of the talus with bone grafting and left knee bone graft harvesting was conducted. Under the sterile technique, a tourniquet was inflated to 300 mmHg and the patient was placed in the supine position with standard draping. The talar neck was approached by a standard dorsomedial approach. Samples were curetted and sent for histopathology tests and tissue culturing ( Figure 4). The anteromedial knee was approached via an oblique incision and bone was harvested from the medial proximal tibia. This was later grafted into the talar defect. The procedure was completed by closing the talar window, washout and subcutaneous and skin closure. Post-operatively, compression stockings were used followed by compression banding and a fracture boot, allowing for full weight bearing. The patient had two doses of antibiotics and started mechanical and chemical anticoagulants and pain management. He was instructed to return for re-dressing in one week and for a review and stitch removal in two weeks. The patient was nonweight bearing for two weeks post-surgery until he was seen at the outpatient department, after which he was allowed to begin progressive weight-bearing.

FIGURE 4: Intra-operative image of the lesion being curetted out
Postoperative histopathology reported a 2 cm benign bone-forming tumour characterised by numerous bony trabeculae with variable osteocyte rimming and prominent vascular stroma. The tumour was shown to have mixed histology containing a significant amount of osteoclast-type giant tumour cells with no background stromal cells. These were consistent with type III cells found in benign GCTs. Results of soft tissue culturing showed no evidence of infiltration on return.
The patient was seen at the outpatient department six weeks post-operatively. The surgical wound was healing well, and he was able to walk freely with no complaints. At the six-month follow-up, the patient was well and there was no radiographical evidence of recurrence or metastasis ( Figure 5). A plan was made for him to continue with physiotherapy and return to the outpatient department in one year.

FIGURE 5: Six-month post-operative radiograph showing the bone graft Discussion
A literature search was conducted on PubMed using the following combination of keywords: "giant cell tumour"; or "giant cell tumor"; or "GCT", and "talus". Results were restricted to English publications with available full-texts and case reports involving GCTs of the talus without any date restrictions. A summary of 16 cases reported in 15 studies can be found in Table 1  Among 16 case studies, 56% of patients were within the 20-40-year-old age range [4,8,10,[13][14][15][16]18] while 31% were under 20 [6,7,11,12,17] and 13% were over 40 [5,9]. The ratio of male to female cases was 7:9 and the duration of symptoms ranged from one month to three years. Since the patient in our case falls in the under-20 category and there are several similar cases in this age group, it should be noted that younger patients seem to be more prone to GCTs of the small bones of the hand and foot, with Chaudhary et al., (2022) stating that 30% of GCTs of bones of the foot are seen in those under-20 [6,7]. GCTs of the foot also tend to be more aggressive than GCTs of long bones with a higher chance of multicentricity [6,7,17]. Varshney et al. (2010) discuss a case of multicentric GCT in the immature skeleton, highlighting that epiphysial plate involvement is associated with the tumour's aggressiveness, and multicentric lesions have a higher risk of metaphyseal involvement and pathological fractures [17]. Given how GCTs of the tarsal bones affect younger and healthier patients, an aggressive tumour localised to an articular region can greatly reduce a patient's quality of life, increasing their risk of fractures, irreparable osseous destruction and metastasis to other organs [12].
Like the patient in this case, the head and neck of the talus were specifically affected in five cases [5,7,10,16] while Varshney et al. (2010) also mention calcaneal involvement [17]. According to Schoenfeld et al. (2007), GCTs affect the calcaneus and metatarsals more than the talus but when the talus is involved, the tumour is most likely localised to the head and neck [15]. Mechlin et al. (1984) stated that among 28 cases of GCT in the tarsal bones, 13 were in the talus, 11 were in the calcaneus, two were in the navicular, one was in the cuboid, and one was in the middle cuneiform [11].
Similar to how the patient in our case was managed using intralesional curettage and autologous bone grafts harvested from his knee, six cases used curettage and bone grafts taken from sites such as the iliac crest [4,6,8,10,12,16] while two used bone cement filling [5,13], one used a synthetic bone graft [17], one used low porosity β-TCP blocks [14], and one used a fresh-frozen osteochondral allograft [15]. Alternatively, three cases involved full talectomies followed by talocalcaneal fusion [7,9] or reconstruction with a 3D-printed prosthesis [18], and two cases involved en bloc resections followed by fusion of the talonavicular joint [10] or tibiocalcaneal fusion [11] with subsequent autologous bone graft. Should surgery be unfeasible, the next course of action involving radiotherapy and denosumab treatment carries the risk of malignant transformation due to radiation [13]. According to Panda et al. (2022), the benefits of bone cement filling overcome the shortfalls of bone grafts, enabling immediate structural support for weight bearing, while producing a thermotoxic effect to kill residual tumours and allowing the early detection of any recurrence [13]. Adverse effects of bone cement are thermal necrosis and long-term degenerative changes in adjacent joints [13]. Novel management with a 3D-printed prosthetic reduces GCT recurrence and restores walking function [18].

Conclusions
Given the higher risk of GCT in the tarsal bones in patients under 20 and the disastrous effect it can have on their quality of life, it must be detected early and removed before it becomes malignant or metastasizes. Traditional treatments of GCTs of the talus continue to appear effective while non-traditional management and novel therapies have also been reported to produce encouraging outcomes. The treatments may also allow recurrence to be detected earlier, reduce recurrence and enable earlier weight bearing and return to normal walking function.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.