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Case Note

Giant Cell Tumour of Talus — A Case Report

Anita Ramdas* K Ramesh Rao**, Abu Thomas***, Renu G’Boy Varghese****, James J Gnanadoss*****

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Key words : Giant cell tumour, talus, skeletally immature.

Giant cell tumour (GCT) of bone is a benign but locally aggressive neoplasm, which is characteristically found in skeletally mature patients at the end of long bones1. The occurrence of GCT in the talar bone is rare with only a few cases reported in literature1-3. When it does occur in the talus, GCT is seen more commonly in the third decade of life2. Here a case of GCT which occurred in the talus of a 15-year-old, skeletally immature boy is reported.

Case Report

A 15-year-old male presented with pain in the left foot of 4 months’ duration.
Examination — Swelling and tenderness of the left ankle was present. Subtalar movements were painfully restricted.
Investigations — Straight x-ray of the left foot revealed an osteolytic lesion in the talus. MRI of the talus strongly suggested the possibility of a primary osseous neoplasm. The blood alkaline phosphatase level was 771 IU, calcium 9.8 mg/dl, phosphorus 5.2mg/dl, Hb 12.8g/dl, total count was 8000/cmm.

Surgery — A trephine biopsy followed by total left talar excision with fibular osteotomy was done. Following the biopsy report, the patient underwent left ankle arthrotomy and excision of talus. The calcaneum was seated with the tibia and fixed with Steinmanni's pins. The postoperative period was uneventful.
Pathology — The trephine biopsy of the lesion showed histological features of GCT; however, considering the young age and the unusual site of the lesion, an excision was advised for confirmation.
Excised specimen of talus measured 7 x 4 x 3cm. The posteromedial surface showed an irregular growth. Cut section showed a lytic lesion measuring 1 x 0.5 cm with one margin breaking the cortex. The rest of the bone appeared unremarkable. Histology confirmed the earlier diagnosis of GCT (Fig 1, H&E, x 40). There was micro-infiltration beyond the cortex in one area.
Follow-up — There was no recurrence at six months follow-up.

Discussion

The present case is unusual not only because of the uncommon site of the GCT but also because of the occurrence of the lesion in a skeletally immature patient of 15 years. Although about 4% of GCTs arise in the foot and ankle, the talus is an uncommon site of involvement by GCT. Natarajan et al4 have reported 4 cases of GCT in the talus. Sung et al1 reported only one case of GCT in the talus in their series of 208 cases. The usual sites of GCT are the distal femur, proximal tibia, distal radius, sacrum and proximal tibia; therefore, the occurrence of a giant cell-containing lesion in the foot or ankle should suggest an alternative diagnosis such as aneurysmal bone cyst, osteosarcoma, giant cell reparative granuloma or hyperparathyroidism. One of the main microscopic differences between true GCT and lesions that simulate it is the spatial relationship between the giant and stromal cells. The former tends to be regularly and uniformly distributed in GCT4.
Most of the GCTs of bone are seen in skeletally mature patients between the 3rd and 4th decade. In the present case, the patient was a skeletally immature male aged 15 years. In skeletally, immature individuals GCT is uncommon with only about 40 cases reported in literature5. Morgan and Eady6 found a 7.5% incidence of GCT of bone in skeletally immature individuals with a mean age of 10.5 years. Most of the cases of GCT of the talus reported in the literature have been in adults with a mean age of incidence of 28 years4. The only exception being the report of Bapat et al2 in a 17-year-old girl. The management of GCT of the foot and ankle includes local procedures like resection, curettage with cement packing and curettage with autologous bone graft. Recurrence rates of 25%, similar to those found in more common locations, have been noted with these procedures4. Although previous reports describe a higher recurrence rate of GCT when found in the small bones of the hands and feet, reported cases of this entity in the talus indicate a less aggressive natural history with rare malignant transformation7. The excision biopsy of the lesion in the present case revealed an area of micro-infiltration of the tumour. Further joint clearance was done.
GCT involving the bones of the hands and feet shows a tendency to be multicentric and to occur in slightly younger population8. In this case, skeletal survey did not reveal any other foci of tumour.
The diagnosis of GCT should be considered in the differential diagnosis of a destructive lesion of bone in skeletally immature individuals8. As the lesion may be multifocal, a patient with a documented GCT of small bone should have a skeletal survey.

Reference

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