Age / Sex : 62 / F

Age/Sex: 62/F

C.C : hip and neck pain for 6 months

PMHx : dialysis for 12 years.

Recent trauma (-), fever (-),

Dialysis-related Amyloidosis of the Hip and Cervical Spine

Discussion

Findings:

1) Lateral radiograph of the cervical spine shows severe narrowing

of the disk space at the C5-C6 level, endplate irregularities and subchondral sclerosis.

2) The noncontrast, axial CT scan through the C5-6 level shows multiple erosions of the vertebral endplate

3) Sagittal spin-echo T1-weighted and sagittal fat saturated spin-echo T2-weighted MR images of the cervical spine show multiple areas of abnormal low signal intensity involving the fifth and sixth vertebral bodies and the intervening disk

4) The corresponding gadolinium-enhanced sagittal spin-echo T1-weighted MR image shows mild enhancement of the adjacent marrow.

5) The axial spin-echo T2-weighted MR image of the hip shows multiple erosions in the femoral head and neck

Pathologic finding:

Total hip replacement was done and the specimen was sent for pathologic examination. Congo red staining of a surgically resected specimen demonstrated applegreen colored amyloid material that was observed under a polarized light microscopy (Congo-red stain, ×400).

Diagnosis: 

Dialysis-related Amyloidosis of the Hip and Cervical Spine

Differential diagnosis

- infectious spondylitis

- gout and calcium pyrophosphate dihydrate (CPPD) crystal deposition disease

Discussion:

Dialysis-related amyloidosis is a relatively uncommon complication resulting from long-term hemodialysis. The incidence of this disease increases with the number of years the patients has been on dialysis. In previous studies, the incidence was reported to be 80% to 100% for the patients who have been undergoing dialysis for over 20 years. When this condition is observed in the spine, it affects the cervical area in most cases (approximately 70%) and less commonly in the lumbar (20%) and thoracic areas (10%).   

Clinically, most patients present with myelopathy or radiculopathy,

and the most serious complication that’s been reported was cord compression as a result of β2-microglobulin deposition in the spinal canal. In case of hip involvement, the patients showing large cystic erosions of the femoral neck had a high prevalence of pathologic fracture. Our patient was surgically treated because of the impending pathologic fracture of the right femoral neck that was secondary to the extensive cystic erosion.

The pathogenesis of spinal abnormalities is still poorly understood. However, mechanical factors seem to be important as the disease is most often detected in the highly mobile segments of the cervical and lumbar spines such as C5-C7 and L3-L5.

Even though there are many radiographic and CT findings of dialysis-related spondyloarthropathy such as significant loss of disk space, endplate irregularities and subchondral sclerosis without significant osteophytosis, it’s difficult to distinguish between dialysis-related spondyloarthropathy and infectious spondylitis. However, dialysis-related spondyloarthropathy shows low signal intensity in the intervertebral disk and the adjacent vertebral endplates on both the T1- and T2-weighted spin echo MR images. On the other hand, infectious spondylitis shows increased signal intensity on the T2-weighted spin echo images. The most important imaging feature that distinguishes dialysis-related spondyloarthropathy from infectious spondylitis is the absence of a paraspinal mass despite of the rapidly progressive discovertebral destruction. In our patient, the 12 years duration of dialysis, the laboratory data and the concomitant disease of the hip joint helped to exclude infectous spondylitis, gout and CPPD. Thus, imaging findings combined with the patient’s history and laboratory data are essential for the assessment of musculoskeletal involvement by the dialysis-related amyloidosis.

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