WBR0405
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Renal |
| Prompt | [[Prompt::A 67 year old African-American female patient with kidney disease on chronic hemodialysis presents to the physician with nocturnal right wrist pain. The patient explains that she has tingling and burning sensation in the right hand along the thumb, index, and middle part of the fourth finger. On physical examination, the patient has asymmetric weakness on thumb adduction with thenar atrophy. Tinel and Phalen signs are both positive. Accumulation of which amyloid product is most likely to be present in this patient’s condition?]] |
| Answer A | AnswerA::Amyloid light-chain (AL) |
| Answer A Explanation | AnswerAExp::Amyloid light-chain (AL) amyloidosis is due to deposition of Ig light chains. It is commonly associated with multiple myeloma. |
| Answer B | AnswerB::β2-microglobulin |
| Answer B Explanation | AnswerBExp::β2-microglobulin amyloidosis causes of amyloidosis in patients on hemodialysis with manifestations as entrapment neuropathy, such as carpal tunnel syndrome. |
| Answer C | AnswerC::Amylin |
| Answer C Explanation | AnswerCExp::Amylin or Islet Amyloid Polypeptide (IAPP) is produced in the beta cells of the pancreas. Amylin amyloidosis is associated with diabetes mellitus. |
| Answer D | AnswerD::A-Cal |
| Answer D Explanation | AnswerDExp::A-Cal protein from calcitonin is seen in patients with medullary thyroid cancer. |
| Answer E | AnswerE::β-Amyloid |
| Answer E Explanation | AnswerEExp::β-Amyloid is the main component of amyloid plaques associated with Alzheimer’s disease. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Carpal tunnel syndrome (CTS) is an entrapment neuropathy of the median nerve that causes pain commonly at night, paresthesia, and burning sensation along the distribution of the distal median nerve. It is commonly bilateral, but patients frequently have clinical manifestations unilaterally. Carpal tunnel syndrome is due to Β2-microglobulin associated amyloidosis in hemodialysis patients. Tinel and Phalen signs are both helpful in the diagnosis of carpal tunnel syndrome. However, they are not very specific or sensitive. Definite diagnosis of carpal tunnel syndrome, and other nerve entrapment neuropathies, is by electromyography (EMG).
Other common entrapment neuropathies include ulnar tunnel, where the ulnar nerve is commonly compressed at Guyon’s canal as it enters the wrist along with the ulnar artery. Tarsal tunnel syndrome (posterior tibial neuralgia) is a compression of the posterior tibial nerve as it passes in the anatomical tarsal tunnel, posterior to the medial malleolus. Educational Objective: Carpal tunnel syndrome (CTS) is an entrapment neuropathy of the median nerve. β2-microglobulin amyloidosis is commonly a cause of CTS in patients on chronic hemodialysis. Reference:
Ullian ME, Hammond WS, Alfrey AC, et al. Beta-2-microglobulin-associated amyloidosis in chronic hemodialysis patients with carpal tunnel syndrome. Medicine (Baltimore). 1989;68(2):107-15. |
| Approved | Approved::No |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |