CASE 111

By: Dr. Nizar Al-Nakshabandi MD, FRCPC

HISTORY: 45-year-old female with knee pain.

What are your findings?

What is the differential diagnosis?

What are the causes?

FINDINGS:

T1 and T2-weighted images with fat saturation demonstrate a lacelike honeycomb appearance bone marrowlesions of low signal intensity on T1 and high signal intensity on T2-weighted images. There is no internal derangement in the knee.

DIFFERENTIAL DIAGNOSIS:

Bone sarcoidosis.

Metastasis.

Multiple myeloma.

Eosinophilic granuloma.

DIAGNOSIS:

Bone sarcoidosis.

PEARLS AND DISCUSSION:

Sarcoidosis is an inflammatory disorder of unknown origin caused by the presence of noncaseating granulomas. Sarcoidosis can involve multiple organs most commonly the lungs, lymph nodes, skin, and eyes but any organ system can be involved including the musculoskeletal system.

Because of its excellent tissue to contrast resolution imaging musculoskeletal abnormalities that are occult on radiographs may be seen on MRI.

Skeletal sarcoidosis occurs in up to 15 percent of patients with sarcoidosis. Primary involvement of the skeletal system without another organ involvement is extremely rare. Approximately 90% of patients have concurrent lung involvement. Always ask for chest x-ray if you suspect sarcoidosis in the bone.

Phalanges of the hands and feet are most frequently affected. However, there is multiple joint involvement as well. On plain films and MRI lacelike honeycomb appears as in this case. Bony erosions can occur with pathological fracture. In the large bone, it can be present as a focal lytic or sclerotic lesion. In the vertebra, it can cause osteolytic lesions with preservation of the disc space. In addition, widespread sclerosis can Occur. If muscles are involved, it can cause a chronic proximal myopathy mimicking polymyositis.

Detection of sarcoidosis musculoskeletal lesions on MRI can change the clinical assessment of granulomatous load and assessment of severity of disease and may therefore influence treatment. Sarcoidosis should also be considered in the differential diagnosis of musculoskeletal lesions detected on MR imaging in patients with suspected or proven sarcoidosis.

FURTHER READING:

1.      Koyama T, Ueda H, Togashi K et-al. Radiologic manifestations of sarcoidosis in various organs. Radiographics. 2004;24 (1): 87-104. 

2.      Talmi D, Smith S, Mulligan ME. Central skeletal sarcoidosis mimicking metastatic disease. Skeletal Radiol. 2008;37 (8): 757-61. 

3.      Moore SL, Teirstein AE. Musculoskeletal sarcoidosis: spectrum of appearances at MR imaging. Radiographics. 2003;23 (6): 1389-99.