Multifocal metachronous giant cell tumor in a 15-year-old boy
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- Stratil, P.G. & Stacy, G.S. Pediatr Radiol (2005) 35: 444. doi:10.1007/s00247-004-1346-x
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We report a case of multifocal metachronous giant cell tumor (GCT) that involved the fibula, tibia, and sacrum of a 15-year-old boy. Multifocal GCT of bone presenting in children is an exceedingly rare phenomenon; however, there is evidence that multifocal GCT presents, on average, at a younger age than solitary GCT. Pediatric radiologists should be aware of this when encountering a single lesion with characteristic radiographic features of GCT and when encountering multiple lytic skeletal lesions.
KeywordsGiant cell tumorMultifocal giant cell tumorMetachronous giant cell tumor
Giant cell tumor (GCT) of bone represents approximately 5% of primary bone neoplasms. The vast majority of GCT affect a single bone of young adult and middleaged adult patients. These neoplasms do not commonly occur in children, and they rarely affect more than one bone. We report a case of a multifocal metachronous GCT that involved the fibula, tibia, and sacrum of a 15-year-old boy.
Giant cell tumors of bone are typically benign but locally aggressive lesions accounting for approximately 5% of primary bone neoplasms . They usually arise at the ends of long bones such as the distal femur and proximal tibia, but can also occur in the pelvis, spine, and small bones of the hands and feet. Patients with GCT present with nonspecific symptoms including pain, overlying soft-tissue swelling, and decreased range of motion at the adjacent joint . GCT present radiographically as a lucent lesion characteristically involving the metaphysis of a long bone, but extending across a closed physis into the epiphysis to abut the articular surface. Often the tumors are located eccentrically within the meta-epiphysis, and they typically have well-defined but non-sclerotic margins. This characteristic appearance often allows a confident radiologic diagnosis.
Skeletal scintigraphy reveals increased radiotracer uptake in the majority of cases, often with central photopenia (Fig. 1). MRI is the study of choice to delineate the true extent of the tumor, which frequently involves the adjacent soft tissues. Although the signal characteristics are often nonspecific, some investigators report that GCT show low-to-intermediate signal intensity on both T1- and T2-weighted images .
Giant cell tumors are typically lesions of young and middle-aged adults, with 80% of tumors occurring in patients between the ages of 20 and 50 years, and a peak prevalence in the third decade of life . GCT are not common in children and receive little attention in pediatric radiologic literature.
Multifocal GCTs are rare, occurring in less than 1% of all patients presenting with GCT . The lesions may present synchronously or metachronously. In the case described above, discovery of the proximal fibular lesion preceded that of the distal tibial lesion by 12 months; the original bone scan showing the proximal fibular lesion did not show a distal tibial or sacral abnormality. The subsequent bone scan revealing the distal tibial lesion failed to show the sacral lesion, which was probably masked by the activity in the urinary bladder.
The etiology of multifocal GCT is unclear. Solitary benign GCTs may metastasize to the lung or undergo malignant transformation (either de novo or following irradiation); however, there does not appear to be any increased risk of pulmonary metastases in patients with multifocal tumors, and pathologic analysis of multifocal GCT reveals findings identical to histologically benign solitary tumors . This suggests that the multifocality of some GCT is not a metastatic phenomenon, but rather represents the separate development of the tumor at multiple sites.
Multifocal GCTs have been described in patients as old as 62 years . The patient presented here was 15 years old at the time of initial diagnosis. A detailed literature review is beyond the scope of this case report, but there is evidence in the orthopedic surgery literature to suggest that the average age of presentation of patients with multifocal GCTs is younger than that of patients with solitary lesions [4, 5]. Cummings et al. , in a review of 29 cases of multicentric GCT, found that 23 of 29 patients (approximately 80%) were 25 years old or younger at the time of original diagnosis. The youngest patient in their series was 10 years old.
Although pediatric radiologists may not frequently encounter GCT, the diagnosis should be considered if a lucent metaepiphyseal lesion with nonsclerotic margins is seen. In the pediatric population, the primary considerations in the differential diagnosis would be a chondroblastoma with metaphyseal extension, or perhaps a telangiectatic osteosarcoma with epiphyseal extension if the lesion appeared to be particularly aggressive. Although chondroblastomas may contain visible calcifications within their matrix, calcifications occurring in GCTs are extremely rare. Telangiectatic osteosarcomas may be purely lytic, as are GCTs; however, GCTs do not typically show the permeative osteolysis and aggressive periostitis that osteosarcomas do.
Given the tendency for multifocal GCTs to occur in a younger age group than solitary tumors, a careful history and physical examination should be performed on all pediatric patients presenting with a GCT to search for additional sites of disease. Children may be embarrassed by certain symptoms related to an underlying neoplasm and therefore be reluctant to discuss them. In the case detailed above, the patient did not reveal his urinary incontinence immediately, thus delaying the diagnosis of the third GCT, located in his sacrum. In patients who present with a lesion suggestive of GCT and additional sites of pain, skeletal scintigraphy should be considered, with subsequent radiographs and MRI examinations performed as needed.
Although the knee is the most common site of involvement in patients with multifocal GCT, there is an increased prevalence of involvement of the small bones of the hands and feet . There is also an increased prevalence of diaphyseal (rather than the usual epiphyseal) extension of the tumor in multifocal cases. This may be particularly true in children who still have open physes, which may act as barriers to epiphyseal spread. Multifocal lesions also appear to be more locally aggressive than their solitary counterparts and have higher rates of recurrence.
The differential diagnosis of multifocal GCT includes multiple brown tumors of hyperparathyroidism . Furthermore, brown tumors may mimic GCTs pathologically. Hence, a metabolic workup should be obtained when multifocal GCT is considered.
In conclusion, our case emphasizes the need for pediatric radiologists to be familiar with the radiographic appearance of GCT and to be cognizant of the fact that multifocal lesions may occur in a younger age group than their solitary counterparts.