Giant cell tumor

Giant cell tumor is a benign but locally aggressive tumor that can occur in any bone. This tumor is uncommon in the foot. The incidence is highest in the third decade. The lesions are located in the metaphysis adjacent to the epiphysis or epiphyseal scar. For this reason, the lesions are located proximally in the first metatarsal (as shown here) and distally in the lesser metatarsals due to the location of the epiphysis.

The typical patient has a history of gradually increasing pain. In the foot a mass may be apparent due to the limited soft tissues. Pain from pathological fracture or microfracture may cause the patient to seek treatment.

Plain radiographs show a lytic lesion without matrix mineralization in the characteristic location. The epicenter is in the metaphysis, and the tumor expands into the epiphysis until it reaches the subchondral bone, which seems to be a partial barrier to further growth.

The tumor can cross joints and affect several ajdacent bones, as shown here. In time, the cortex may be expanded and even destroyed. In smaller bones, the lesion can slowly expand the entire bone into a oversized balloon with cartilage on the end as shown here.

An "extended curettage" is performed by mechanical currettage plus the application of adjuvant local treatment, such as liquid nitrogen, phenol, or a high speed burr. In this way potential microscopic amounts of tumor tissue that may be present in the margins of the curetted cavity are eliminated, and the rate of local recurrence is reduced. Local recurrence may be treated by repeat extended curettage, or if local control seems impossible, by wide excision and reconstruction with a bone graft.

After performing the "extended curettage", the cavity is filled with a suitable material, such as morcellized bone graft, bone graft substitute, or polymethylmethacrylate bone cement. The heat of polymerization of the PMMA cement may help kill residual tumor cells and lower the rate of local recurrence.

Highly expansile primary lesions of the lesser bones of the foot may be excised and the bone may be reconstituted with a structural autograft from the iliac crest with excellent results. Lesions of the phalanges of smaller the lesser toes should be amputated.

Pathology of giant cell tumor:

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