H/O pain and swelling over the left forearm.
There is evidence of a mass lesion arising from the
proximal left radius with resultant expansion. It is seen to destroy the head and neck of
the radius. Distally there is a sharp cut off with the normal marrow (8.5 cms. distal to
the elbow joint). This lesion is hyperintense to muscle but hypointense to fat on the T1W
images and hyperintense to both on the T2W and STIR images. Also seen are cystic/necrotic
areas within this lesion. The proximal radio-ulnar joint appears to be involved.
Patients usually present with pain and swelling. The larger lesions may present with fractures.
Location:
Giant Cell Tumors (GCTs) comprise approximately 4.2% of all bone tumors. 65% of these tumors are seen in patients 20 to 50 years of age. They usually occur in the distal metaphysis of the long bones and after closure of the cartilaginous growth plate (3% occur prior to closure). Common sites of predilection are around the knee and wrist joints. Occasionally the lesions may be multicentric. Rarely they involve the spine (usually the anterior elements-body).
Pathology:
GCTs are fleshy, friable reddish-brown lesions with occasional necrotic areas. Sometimes they may present as a cyst like lesion. Histologically, these tumors show a uniform distribution of multinucleated giant cells against a cellular background of ovoid spindle stromal cells. Osteoid foci may be seen within these lesions (usually with areas of hemorrhage or within a fracture callus) Xanthomatous changes may be seen. Giant cell tumors exhibit unpredictable biologic behavior and 10% to 20% have potential for malignant transformation (usually after irradiation of the original tumor). Systemic spread may be seen, usually the lungs, in approximately 1% to 3% of cases (usually passive vascular transports related to surgical curettage).
On MRI:
GCTs arising from long bones are usually well-defined and are of
low to intermediate signal intensity on the T1W images and high signal intensity on the
STIR andT2W images. Heterogeneity on the STIR and T2W images may represent areas of
liquefaction, hemorrhage, or necrosis (the aggressive lesions invariably exhibit increased
signal inhomogeneity). Areas of marked hypointensity may be seen on the gradient rephased
images and may represent hemosiderin (probably a result of extravasation of RBCs and the
phagocytic function of the tumor cells). Occasional fluid-fluid levels may be seen within
the lesion. Cortical erosions, limited periosteal reaction, soft tissue extension (rarely
the joint may be invaded) and joint effusion may be identified. A thin rim of sclerotic
bone is usually seen at the tumor interface with uninvolved fatty marrow in less
aggressive lesions.
The usual form of treatment is curettage or intralesional resection with the use of
polymethylmethacrylate cement. Recurrent tumors (after excision and packing with
methylmethacrylate) may exhibit low to intermediate signal intensity on the T1W images and
high signal intensity on the STIR and T2W images. Occasionally soft tissue nodular seeding
(occasionally calcified) may be seen post surgery.
Differential Diagnosis:
GIANT CELL TUMORS WITH FLUID-FLUID LEVELS |
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MULTICENTRIC GIANT CELL TUMORS |
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In the spine, aneurysmal bone cysts usually involve the posterior elements. They are mostly hyperintense with a hypointense rim on the T2W images. They also have fluid-fluid levels with diverticula like projections.