WBR0405
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Renal |
| Prompt | [[Prompt::A 67-year-old female, with kidney disease on chronic hemodialysis, presents to the physician's office with complaints of nocturnal right wrist pain. The patient explains that she has a tingling and burning sensation in her right hand along the thumb, index, and middle part of her fourth finger. Upon physical examination, the patient has asymmetric weakness on thumb adduction with thenar atrophy and Tinel and Phalen signs are both positive. Accumulation of which of the following amyloid products is most likely to manifest in this patient’s condition?]] |
| Answer A | AnswerA::Amyloid light-chain (AL) |
| Answer A Explanation | [[AnswerAExp::Amyloid light-chain (AL) amyloidosis, which results from deposition of Ig light chains, is commonly associated with multiple myeloma.]] |
| Answer B | AnswerB::β2-microglobulin |
| Answer B Explanation | AnswerBExp::See explanation. |
| 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 frequently 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, frequently associated with Alzheimer’s disease. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Carpal tunnel syndrome (CTS) is an entrapment neuropathy of the median nerve, which causes pain often occurring at night, paresthesia, and a burning sensation along the distribution of the distal median nerve. It is commonly bilateral, but patients frequently have clinical manifestations unilaterally. Carpal tunnel syndrome results from Β2-microglobulin associated amyloidosis in hemodialysis patients. Tinel and Phalen signs often aid in the diagnosis of carpal tunnel syndrome, but they are not very specific or sensitive. Definite diagnosis of carpal tunnel syndrome, and other nerve entrapment neuropathies, is based on 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, and tarsal tunnel syndrome (posterior tibial neuralgia), a compression of the posterior tibial nerve as it passes in the anatomical tarsal tunnel, posterior to the medial malleolus. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Beta-2-microglobulin, WBRKeyword::hemodialysis, WBRKeyword::carpal tunnel syndrome, WBRKeyword::CTS, WBRKeyword::neuropathies, WBRKeyword::nerves, WBRKeyword::nervous system |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |