Enchondroma of the proximal humerus

Diagnosis

Enchondroma of the proximal humerus

History

Incidental finding of a left proximal humerus lesion.

Findings

Radiographs:

Lytic lesion with well defined margins, no periosteal reaction and popcorn like calcifications of the left proximal humerus (@1.1).

MRI:

Six centimeters lesion of the proximal humerus with lobulated contours and very high signal intensity on T2-weighted images with fat suppression (@2.9).

Focal regions of signal drop out corresponding to calcifications (@4.14) seen on x-rays.

The lesion is well-defined with normal marrow fat interposed between the cartilaginous lobules (@5.10).

After administration of gadolinium, there is a peripheral and septal ("rings and arcs") enhancement (@6.9).

No endosteal scalloping, no periosteal reaction, no soft tissue mass.

Conclusion:

Radiograph and MRI demonstrate benign cartilaginous lesion which most likely represents enchondroma of the humerus.

DDx

• Low grade chondrosarcoma
• Bone infarct

Key points

- Asymptomatic

- Well defined

- No cortical scalloping

- No soft tissue mass