A 65-year-old man presents to his primary care physician with complaints of progressive bilateral shoulder pain over the last two months. He denies any known trauma. He has a history of end-stage renal disease secondary to type 2 diabetes mellitus, hypertension, and secondary hyperparathyroidism. He receives hemodialysis three times per week. Medications include lisinopril, chlorthalidone, insulin, atorvastatin, calcitriol, and sevelamer. Physical examination is consistent with scapulohumeral arthritis, and shoulder X-rays are consistent with this.
Which of the following is most likely to be present if biopsy of this patient’s rotator cuff were performed?
C) Beta2-microglobulin fibrils
Patients with end-stage renal disease (ESRD) who are on dialysis have decreased clearance and subsequent accumulation of beta2-microglobulin. The most common resulting clinical manifestations of beta-2 microglobulin amyloidosis are osteoarticular complaints including scapulohumeral arthritis and rotator cuff infiltration. Destructive spondyloarthropathy (typically manifesting as neck pain) and carpal tunnel syndrome may also occur.
Answer choice A: Amyloid A fibrils, is incorrect. Amyloid A is an acute phase reactant that accumulates in secondary amyloidosis, which occurs due to chronic inflammation. Clinical manifestations are similar to those of primary amyloidosis, with renal involvement being most common and cardiomyopathy being less common.
Answer choice B: Amyloid light chain fibrils, is incorrect. Amyloid light chain fibrils accumulate in primary amyloidosis, which can occur in patients with plasma cell dyscrasias such as multiple myeloma. Excessive immunoglobulin light chain production results in nephropathy with heavy proteinuria, hepatosplenomegaly, cardiomyopathy, and carpal tunnel syndrome.
Answer choice D: Diffuse calcifications, is incorrect. Diffuse calcifications may be found in calcific tendinopathy. Although calcific tendinopathy develops gradually and is unrelated to trauma, shoulder X-rays would likely reveal calcified deposits. Beta2-microglobulin amyloidosis is more likely in this patient with ESRD.
Answer choice E: Transthyretin amyloid fibrils, is incorrect. Transthyretin (also known as pre-albumin) accumulates in age-related amyloidosis. Common clinical manifestations include neuropathy, cardiomyopathy, and carpal tunnel syndrome. Unlike other forms of amyloidosis, renal involvement is rare.
Key Learning Point
Amyloidosis secondary to end-stage renal disease (ESRD) is characterized by deposits of beta2-microglobulin, which can present with arthropathy. Other types of amyloidosis include AA amyloidosis which is secondary to chronic inflammation, AL amyloidosis which is secondary to plasma cell dyscrasias, and ATTR amyloidosis which is typically age-related.
