Key Information
Source
Year
2024
summary/abstract
Key words
Amyloid
Amyloidosis
Amyloidosis screening
Cardiac amyloidosis
Stenosing flexor tenosynovitis
Trigger digit
Trigger finger
The amyloidoses are a heterogeneous group of disorders caused by the extracellular deposition of insoluble amyloid fibrils into various tissues including the heart, kidneys, liver, nerves, and gastrointestinal and musculoskeletal systems. Amyloid fibrils disrupt the architecture of the affected organ(s) to cause clinical manifestations of the disease. Cardiac involvement in patients with systemic amyloidosis is the strongest predictor of mortality and is common in two of the most prevalent types, transthyretin (TTR) amyloidosis and immunoglobulin light chain amyloidosis. The development of heart failure carries an extremely poor prognosis, with median survival rates of 6 months and 4 years after presentation in patients with immunoglobulin light chain amyloidosis and TTR amyloidosis, respectively.1external link, opens in a new tab Although treatment of cardiac amyloidosis was previously limited to symptom management, disease-modifying therapies are now available. The mechanisms of action of these drugs focus on preventing disease progression by either stabilizing precursor proteins or inhibiting the synthesis of these proteins. Because therapy for amyloid cardiomyopathy is most effective when initiated before the onset of clinically apparent cardiac dysfunction, early identification of affected individuals is critical to prevent morbidity and mortality related to heart failure or conduction abnormalities.2external link, opens in a new tab
Musculoskeletal conditions such as carpal tunnel syndrome, biceps tendon rupture, spinal stenosis, and rotator cuff disease are also frequently seen in amyloidosis, and these manifestations often precede cardiac disease by several years.3external link, opens in a new tab Accordingly, there has been interest in amyloidosis screening during routine orthopedic procedures. For instance, screening tenosynovial biopsy at the time of carpal tunnel release is increasingly performed for patients at increased risk of amyloidosis, although the optimal criteria for screening have yet to be defined.1external link, opens in a new tab,4external link, opens in a new tab
Trigger digit, or stenosing flexor tenosynovitis, is another common musculoskeletal condition associated with amyloidosis, estimated to affect 2% of the general adult population. There is an increased incidence of amyloidosis and heart failure among patients undergoing trigger release surgery; therefore, amyloidosis screening during trigger release surgery represents another potential means of early diagnosis and treatment of amyloidosis.5external link, opens in a new tab However, the few studies available on this topic report the widely variable prevalence of amyloid among biopsies performed during trigger release (2% to 65%), and no biopsy-positive patients in published studies have been diagnosed with occult cardiac amyloidosis or started on disease-modifying therapy.6external link, opens in a new tab, 7external link, opens in a new tab, 8external link, opens in a new tab, 9external link, opens in a new tab, 10external link, opens in a new tab We present a case of a patient with cardiac amyloidosis diagnosed from a biopsy taken during trigger release surgery and subsequently started on disease-modifying therapy. We also review the existing literature on this topic.
Case Presentation
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A 71-year-old right hand–dominant white male engineer with a medical history of immunoglobulin G kappa monoclonal gammopathy of unclear significance (MGUS), longstanding peripheral neuropathy, and multiple prior trigger digit releases developed left index finger triggering of about 1 year’s duration for which he was referred to hand surgery. Given the patient’s peripheral neuropathy of uncertain etiology and clinical suspicion of amyloidosis being evaluated by his neurologist, the patient had undergone an ultrasound-guided abdominal fat pad biopsy 2 months prior to his presentation for trigger finger, which returned negative. Considering his age, history of multiple trigger digits, MGUS, and peripheral neuropathy, we recommended a biopsy at the time of his trigger release surgery to evaluate for amyloidosis.
A standard A1 pulley release was performed under a local anesthetic. Intraoperative findings included a thick nodule of the flexor tendons at the level of the A1 pulley along with thickening of the pulley. As there was no tenosynovium evident within the tendon sheath at this level, a full-thickness portion of the A1 pulley measuring approximately 5 × 5 mm (corresponding to about half the proximal-to-distal length of the pulley) was sent to pathology. Congo red staining demonstrated foci of amyloid deposition (Fig. 1external link, opens in a new tab), and subtyping by mass spectrometry was consistent with TTR amyloidosis. Genetic testing was negative for transthyretin mutation, confirming wild-type transthyretin amyloidosis.