Aggressive giant cell tumour of the metacarpal

A 54-year-old female patient presented with a 2-month history of insidious onset of swelling and pain at the left thumb. Initial conservative treatment failed. Physical examination confirmed swelling at the 1st carpometacarpal (CMC) joint and a limited abduction. The patient was otherwise well with no history of prior malignancy.

Plain radiographs demonstrated an expansile osteolytic lesion in the proximal epiphysis and diaphysis of the left 1st metacarpal bone (MC1). The cortex appeared markedly thinned. There was no surrounding sclerosis nor periosteal reaction (Fig. 1). CT confirmed a large lytic lesion with soft tissue attenuation, cortical thinning and destruction (Fig. 2). MR imaging showed bone marrow replacement with distal epiphyseal sparing. The lesion was of low signal intensity (SI) on T1-weighted images (WI) and intermediate to high SI on T2-WI. Moderate enhancement and soft-tissue extension was noted on contrast-enhanced images (Fig. 3). Bone scintigraphy demonstrated increased radionuclide uptake but absence of multifocality (Fig. 4). Surgical biopsy and subsequent histopathological examination revealed Giant Cell Tumour (GCT). Preoperative imaging (Fig. 5-6) 3 months later preceding MC1 resection (Fig. 7) and cement grafting (Fig. 8) showed marked increase of the lesion size. Histopathological findings of the resection specimen confirmed GCT without malignant degeneration.

GCT of bone is a benign, but locally aggressive lesion with a tendency for local recurrence after resection. Metastasis is rare. Histologically, it is composed of multinucleated giant cells within a stroma of mononuclear cells. GCT account for approximately 5% of all primary bone tumours [1, 2]. It predominantly occurs between 20 and 50 years of age with a female predominance [1, 3, 4].

GCT of the bone commonly occur in the epi-metaphyseal region of long bones. The distal femur, proximal tibia and distal radius are commonly involved, with the spine and sacrum being less involved [3, 5]. The bones of the hand and foot are rarely involved, with a reported frequency of about 2% of all GCT. Metacarpal involvement is extremely rare [5].
Clinical presentation is usually nonspecific including pain, swelling, limited range of motion and pathological fractures [1, 5].

On conventional radiographs and CT, GCT is typically seen as an eccentric, epi-metaphyseal osteolytic lesion, with well-defined non-sclerotic border and extension underneath the subchondral articular bone [1-3, 5-7]. GCT may also show aggressive features consisting of poorly demarcated margins, cortical thinning and destruction and soft tissue extension [5]. CT may be useful in evaluating cortical bone integrity, absence of matrix mineralisation and demonstration of pathologic fracture [2, 4]. GCT of the hand tends to be less eccentric and more centrally located [7].

MR imaging can help determine the precise intramedullary and soft-tissue extent of the lesion [7]. Generally, GCT has a low-to-intermediate signal on T1-WI and a heterogeneous-high signal on T2-WI [2-4, 7]. However, due to intra-tumoural haemosiderin or fibrosis, the signal may be low on T2-WI [2]. The lesion enhances after intravenous gadolinium contrast administration, reflecting the increased vascular supply [6].
Bone scintigraphy may detect multifocality [4].

Extensive curettage or resection is the treatment of choice of GCT of the hand bones [2, 6, 7]. The combination of intraoperative cryogenic agents or methyl-methacrylate packing and resection has resulted in a recurrence rate of less than 10% [6]. For maintenance of the CMC function, resection is followed by bone reconstruction using an autogenous bone graft or allograft [2].

Although histology is mandatory for a definitive diagnosis, analysis of imaging characteristics of a lesion can be helpful in suggesting the correct diagnosis of a GCT. Epiphyseal extension and the low SI on T2-WI on MRI are useful signs in imaging characterisation of aggressive GCT even at rare localisations such as the metacarpal.

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