Multicentric giant cell tumour of bone.

Although giant cell tumour (GCT) is seen quite frequently, multicentric giant cell tumour (MCGCT) is a rare entity occurring in less than 1% of patients with GCT. The pathogenesis of MCGCT is debated; various mechanisms have been postulated, including contiguous spread, iatrogenic tumour cell seeding, benign metastasis, malignant transformation and de novo formation. A literature review revealed 101 cases of MCGCT reported worldwide, of which we could trace and review 83 cases. We noted that MCGCT, unlike the solitary GCT, more frequently involves the short bones of the hand and feet and is commoner in the meta-diaphyseal region of long bones. The present literature review noted a higher incidence in females and skeletally immature patients (21%). Individual lesions in a patient with MCGCT are radiologically and histologically indistinguishable from the solitary GCT. In our review we noted 42 recurrences in 157 lesions (26%), thus negating the commonly held point of view that MCGCT was clinically more aggressive. Four lung metastases and two histologically malignant lesions were found. The literature does not define the exact time period beyond which a lesion can be classified as metachronous; however a significant number of the subsequent lesions occur within 2-3 years of the index lesion. We recommend from our review, that with the present state of knowledge, special care should be taken in cases with primary meta-diaphyseal lesions, GCTs seen at atypical locations, and in females of younger age group, to ensure that multicentricity is picked up earlier.