A Case Report of Giant Cell Tumor of Proximal Fibula in Children

Giant cell tumour (GCT) is histopathologically benign tumor of long bone particularly in distal femur and the proximal tibia. It commonly occurs in adults of age 20-40 years but rare in children. GCT is considered to be locally aggressive tumor and tendency of recurrence is higher even after surgery. The clinical features are nonspecific, the principle symptoms are pain, swelling and limiting adjacent joint movements. Diagnosis is based on the radiographic appearance and histopathological findings .In our case X-ray showed ill defined lytic lesion on proximal fibula with cortical thinning and MRI finding revealed expansile lytic lesion in meta-epiphysis of right fibula 16×16×28mm adjacent to growth plate with fluid level. The sclerotic rim appears hypointense on T1 & hyperintense on T2. Core needle biopsy showed giant cell tumor on proximal fibula. Considering the risk of recurrence wide local excision was done. Management of GCT of proximal fibula in young patient is critical for preventing recurrence and enhancing functional outcomes by saving adjacent anatomical structure. No evidence of local recurrence and metastasis was found in 24 months of follow up. Introduction Histopathologically Giant cell tumor (GCT) is a common benign tumor of long bone. It is classified as osteoclastic gaint cell rich tumors of intermediate grade with local aggressiveness and capacity to metastasize. GCT commonly occurs in mature skeleton. The incidence of occurrence lies between age 20 to 40 years but rare in children.1-3 The common sites for GCT in long bone are distal femur and proximal tibia.4-5 Literatures showed that GCT in the immature skeleton varies from 1.8% to 10.6%.6 A retrospective study conducted in GCT by Strom et.al in Oslo, Norway from 1984-2015 found that out of 154 patients 89% were more than 15 years. This finding reveled that GCT is more in mature skeleton than in immature skeleton. The biological characteristics, symptom and treatment of the tumor in children do not differ from the adults.7-8 The principal symptoms are pain and swelling around affected joints followed by limited movements and sometimes presents with pathological fractures. The definitive diagnosis is based on radiographic and histopathological finding. Universally surgery is primary treatment for GCT. Commonly practicing surgical treatment are extended currattage with through the use of power burr, Phenol, liquid nitrogen, bone cement, hydrogen peroxide, zinc chloride and argon beam cauterization. Selection of appropriate surgical treatments plays a vital role in reducing recurrence rate for functional as well as oncological outcomes. Case report Seven years boy came to the BPKMCH with the features


Introduction
Histopathologically Giant cell tumor (GCT) is a common benign tumor of long bone. It is classified as osteoclastic gaint cell rich tumors of intermediate grade with local aggressiveness and capacity to metastasize. GCT commonly occurs in mature skeleton. The incidence of occurrence lies between age 20 to 40 years but rare in children. [1][2][3] The common sites for GCT in long bone are distal femur and proximal tibia. [4][5] Literatures showed that GCT in the immature skeleton varies from 1.8% to 10.6%.6 A retrospective study conducted in GCT by Strom et.al in Oslo, Norway from 1984-2015 found that out of 154 patients 89% were more than 15 years. This finding reveled that GCT is more in mature skeleton than in immature skeleton. The biological characteristics, symptom and treatment of the tumor in children do not differ from the adults. [7][8] The principal symptoms are pain and swelling around affected joints followed by limited movements and sometimes presents with pathological fractures. The definitive diagnosis is based on radiographic and histopathological finding. Universally surgery is primary treatment for GCT. Commonly practicing surgical treatment are extended currattage with through the use of power burr, Phenol, liquid nitrogen, bone cement, hydrogen peroxide, zinc chloride and argon beam cauterization. Selection of appropriate surgical treatments plays a vital role in reducing recurrence rate for functional as well as oncological outcomes.
Official Journal of B P Koirala Memorial Cancer Hospital BPKMCH of pain and swelling over lateral aspect of right proximal leg for two months duration. Pain was gradual in onset, dull aching, and progressive, localized without increasing on knee movements. There was no history of fever, limping, instability, locking and other constitutional symptoms. Examination showed diffused swelling over proximal fibula at lateral knee region ( figure 1). X-ray showed ill defined lytic lesion on proximal metaphyseal region of fibula with cortical thinning (figure 2). For further confirmation of diagnosis MRI was done and finding revealed expansile lytic lesion in metaphysis of right fibula 16×16×28mm adjacent to growth plate with fluid level. The sclerotic rim appears hypointense on T1 & hyperintense on T2. Hematological and biochemical parameters were normal. Core needle biopsy was taken out and showed giant cell tumor. Considering recurrence risk patient was counseled for excision of fibular head instead of extended curettage. Wide excision of tumor was done protecting common peroneal nerve and lateral collateral ligaments and bicep femoris was anchored at proximal tibia with non absorbable sutures (figure 3, 4). Histopathological examination showed numerous multinucleated giant cells scattered among oval to spindle cells without atypia or mitotic features suggesting giant cell tumors. Post operatively child was kept on supportive brace for two weeks and gradually walking as pain tolerated. No ligament instability on varus stress test and can walk without pain and squats normally.
There is no evidence of local recurrence & metastasis till 24 months follow up (figure 5). The patient was kept for regular follow up for identifying local recurrence swiftly. Informed consent was taken from patient's parties for disseminating valuable information for exploring knowledge.

Discussion
GCT is benign tumor with local aggressiveness thus it should be well treated. The incidence of occurrence is higher in adults between 20-40 years of age and more common sites are distal femur and proximal tibia. [1][2][3] In our case, 7 years boy was diagnosed with GCT of proximal fibula. Studies suggested that both age and location of tumor is the rare condition. 9, 10 Being a rare disease limited studies has been conducted regarding GCT of children. Different studies showed GCT in immature skeleton representing 0.5%-10.6% of total GCT. 11 Picci et al. have reported 6 cases of GCT in children around knee. 12 GCT is locally aggressive tumor with higher tendency to recur after removal. 13,14 The recurrence rate of tumor after surgery varies between studies. A multicentre retrospective study conducted in China between 2000-2014 regarding recurrence rate of primary GCT around knee among aged 20-39 years population was found 23.4% of local recurrence rate and according to location recurrence rate was also higher in proximal fibula as compared with distal femur. 9 Figure 2 : Pre-op Xray knee Selecting the appropriate treatment is the way to minimize the recurrence rate. But treatment dilemmas still existing related to functional and oncological outcomes. The aim of the treatment was to remove the tumor completely preserving surrounding anatomical structures for functional outcome. Treatment of GCT in children is same like in adults with similar rate of recurrence. 7,8 we performed wide local excision of tumor saving common peroneal nerve and lateral collateral ligament and bicep femoris muscle to proximal tibia with non-absorbable sutures. The studies suggested that the rate of recurrence is lower with the wide local excision. 10,[13][14][15][16]  A retrospective study conducted in China regarding recurrence rate of GCT around the knee showed higher rates of recurrence in treatment with intralesional curettage and curettage combined with resection as compared with en bloc marginal resection. 9 A study conducted by Klenke et.al between 1958 -2005 found lower recurrence rate in patient treated with wide resection was only 5% and 25% with intralesional surgery. 16 In wide local excision, preserving peroneal nerve is crucial for preventing functional impairment of the long bone.

Conclusion
GCT is benign tumors of bone with local aggressiveness and higher tendency to recur after surgery. Considering aggressiveness of tumor wide local excision preserving common peroneal nerve and anchoring lateral collateral ligament was suitable option for optimum functional and oncological outcome. There was no evidence of local recurrence after 24 months of follow up.
GCT is rare condition in children in terms of age as well as site. The aim of this study was to explore knowledge on rare disease for contributing in the field of Orthopedic Oncology.