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Table 1 Imaging and pathological features of the patient

From: Epiphyseal enchondroma masking as osteoid osteoma: a case report

 

Findings

Roentgenography

Increased density of the greater trochanter of the left femur (Fig. 1)

CT

The cortex was thickened, with a size of 6.4 × 1.7 cm, in the anterior surface of the left proximal femur with specks of calcification and inhomogeneity of the adjacent bone marrow cavity. Cord-like and patchy hyperintense shadows were present. No apparent abnormality in adjacent oft tissues. The findings were highly suggestive of left femur tumor with a high likelihood of osteoid osteoma (Fig. 2)

MRI

A hypointense oval mass, 5.5 × 2.1 cm in size, was seen in the bone marrow cavity of the proximal femur in the T1-weighted image. The mass was 5.47 × 2.14 cm in size and hyperintense in the fat-suppressed T2-weighted image. The intertrochanteric bone had slightly sheet-like hyperintense signal on fat suppression and a sharp protrusion was seen anterior to the lesion and its wide base was connected to the bone. The adjacent soft tissue showed a long curved shadow on T2 fat-suppressed signal (Fig. 3)

Pathology

The medullary cavity was mainly composed of lobulated, well differentiated cartilage. The cellular density increased in the lesion, the nuclei of chondrocytes appeared large and irregular. Varying degrees of sclerotic bone reaction surrounded the lesion, and the trabeculae were in disarray with fibrous connective tissue overgrowth. Newly formed trabeculae were seen, and the soft tissues adjacent to the femur were hyperemic with focal bleeding. The vessels of small vessels became thickened and the amount of fibrous connective tissue increased with infiltration of inflammatory cells. Mucoid degeneration and muscle atrophy were present (Fig. 4)

Electromyography

Injury of the left femoral nerve

Intraoperative findings

Soft tissue swelling was observed adjacent to the lesion in the proximal femur. The periosteum became thickened and the bone in the lesion site was thickened and rough. The lesion was excised for pathological examination. Massive granulation tissues were present in the medullary canal

Follow-up

The patient received follow-up at the hospital at 1, 3, 5 and 18 months postoperatively. The left hip showed a good range of motion including flexion, adduction and medial and lateral rotation. The patient could ambulate without difficulty. Signs of left femoral nerve injury disappeared. Roentgenography showed irregular patchy inhomogeneous hypodense shadows with an indistinct border. No other abnormalities were seen