Solution to Unknown Case # 3 – Osteosarcoma of the Left Humerus

History: 17 year old male with left shoulder pain. 

Osteosarcoma of the left humerus: Axial fluid sensitive MRI of the left shoulder reveals marked heterogenous hyperintensity within the left humeral head (yellow arrow). A complex joint effusion is present within the anterior recess (green arrow).

This is a case of osteosarcoma of the left humerus. Osteosarcoma is the most common malignant primary bone tumor in children and young adults, and is usually seen in patients 10-30 years of age and patients older than 60 years of age, but more commonly in the adolescent years.

Osteosarcoma is an aggressive bone tumor that is seen in the humerus in approximately 15% of cases. On MRI it can have areas of low T1 and T2 signal in mineralized tumor, and high T1 and T2 signal in soft tissue mass and non-mineralized portions of the tumor.

The differential diagnosis for this shoulder MRI includes osteosarcoma or Ewing sarcoma, and possibly less likely osteomyelitis and lymphoma.

For an interesting case of extra-skeletal osteosarcoma, click here.