Age / Sex : 14 / F

Chief complaint: Left shoulder pain for 5 months

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(답안은 한 개만 보내주시기 바랍니다)

Courtesy: 박지선 (Ji Seon Park), 경희대학교병원 (Kyung Hee University Hospital)

Chondroblastoma

Discussion

Findings: Radiographs reveal a well-defined, slightly lobulated, osteolytic lesion with thin sclerotic rim at epiphysis of left humeral head and thin linear periosteal reaction along the cortex of proximal humeral metadiaphysis. Calcification within the osteolytic lesion is not definite on these radiographs. Bone scintigraphy shows intense uptake at left humeral head. On MRI, the osseous lesion of left proximal humeral epiphysis demonstrates low signal intensity (SI) on T1-weighted image, heterogeneously intermediate to high SI on T2-weighted image and heterogeneous enhancement on fat-suppressed enhanced T1-weighted image, with sclerotic rim and internal foci of low SI on all sequences. Internal low signal foci suggest calcification or hemosiderin. Fat-suppressed T2-weighted coronal image shows extensive marrow edema, periosteal reaction, and deep soft tissue edema at anteromedial aspect of proximal humeral shaft.

Differential Diagnosis: Osteomyelitis

Diagnosis: Chondroblastoma

Discussion:

Chondroblastoma is one of the benign cartilaginous tumors arising in epiphysis of immature skeleton. It occurs in the second and third decades and men are affected more commonly. It usually involves epiphysis or apophysis of long tubular bones such as humerus, tibia, and femur and occasionally extends to metaphysis. And, tarsal bones such as calcaneus and pelvic bones can be involved. Major symptoms include local pain, swelling, and tenderness. Radiographically, the lesion shows an eccentric, well-defined or geographic, osteolytic lesion with thin sclerotic margin and may associate internal chondroid calcification (30~50%) or smooth periosteal reaction (50%) or secondary aneurysmal cyst with fluid-fluid level. Radiographic differentiation may include osteomyelitis or eosinophilic granuloma, however, these two lesions usually involve metadiaphysis. In some cases, differentiation from giant cell tumor, which originates in metaphysis and extends to epiphysis, may be necessary. Bone scintigraphy demonstrates hot uptake with accumulation of radioactive agent. MRI reveals heterogeneously low signal on T1-weighted image, heterogeneous high SI on T2-weighted image, and heterogeneous enhancement. Low signal foci on T2-weighted image correspond to chondroid matrix calcification or hemosiderin. Edema of adjacent marrow and soft tissue is common and these findings may need for differential diagnosis from aggressive or infectious lesions.

References:

Resnick D.: Bone and joint imaging, 3^rd ed. Philadelphia: Elsevier-Saunders, p.1144

Manaster BJ. Diagnostic imaging. Musculoskeletal: non-traumatic disease. Friesens: Amirsys, p.86-89

Bloem JL, Mulder JD. Chondroblastoma: a clinical and radiological study of 104 cases. Skeletal Radiol 1985;14:1-9