Age / Sex : 13 / M

Chief complaint : left foot swelling 1 year ago

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : So Young Park, Kyung Hee University Hospital at Gangdong

Discussion

Answer:  chondroblastoma

Findings:

Radiograph – a well-defined lobulated osteolytic lesion with sclerotic rim and surrounding ill-defined sclerosis are seen in the calcaneus. The lesion is close to the talocalcaneal joint.

Outside hospital MR – a well-defined lobulated calcaneal lesion is seen with dark signal intensity rim, slightly increased signal intensity than that of muscle on T1WI, heterogenous signal intensity on T2WI, and heterogenous enhancement. Surrounding bone marrow edema and enhancement, surrounding soft tissue edema or inflammation, and synovitis of tibiotalar and talocalcaneal joint are seen.

CT – a well-defined lobulated osteolytic lesion is seen in the calcaneus, close to the talocalcaneal joint. Focal cortical depression at articular surface, internal calfic foci, sclerotic rim and surrounding ill-defined sclerosis are seen.

Differential Diagnosis: giant cell tumor, chondrosarcoma, osteosarcoma, fibrosarcoma, osteoblastoma, enchondroma, tuberculosis, chondromyxoid fibroma, Langerhans cell histiocytosis

Discussion:

• Rare benign cartilaginous bone tumor derived from epiphyseal chondrocytes


• <2% of all primary bone tumors


• Male>female (2:1 to 5:1)


• The second decade of life


• Arising in the epiphysis or apophysis


• Calcaneal chondroblastoma: adjacent to the talocalcaneal articulation or in the posterior calcaneus


• Symptoms: insidious onset of localized pain, swelling, and tenderness


• Radiograph: an osteolytic lesion surrounded by thin sclerotic rim, with or without internal calcification


• CT: well-defined osteolytic lesion, mineralization of matrix, soft tissue extension, cortical erosion


• MR: low signal intensity on T1WI, high or variable signal intensity on T2WI, dark signal intensity rim corresponding to the thin sclerotic margin, internal lobular and septal enhancement, periosteal reaction, adjacent bone marrow and soft tissue edema, and joint effusion(1, 2)

References:

1. Dutt L, Schade VL, Manoso MW. Calcaneal chondroblastoma with pathologic fracture and recurrence. J Foot Ankle Surg 2015;54:258-267


2. Kricun ME, Kricun R, Haskin ME. Chondroblastoma of the calcaneus: Radiographic features with emphasis on location. AJR Am J Roentgenol 1977;128:613-616