Examkin

Soru

Zorluk: ZorHematology and Oncology

A 65-year-old man presents to the clinic with a 4-month history of progressive fatigue, shortness of breath on exertion, and frothy urine. Physical examination reveals periorbital purpura, an enlarged tongue with lateral indentations, and 2+ pitting edema of the lower extremities. Jugular venous distention is present. Echocardiography demonstrates thickened left and right ventricular walls with a sparkling, granular appearance and an ejection fraction of 55%. Urinalysis shows 4+ proteinuria, and a 24-hour urine collection confirms 5.2 g of protein. Suspecting an underlying hematologic disorder, the physician plans a diagnostic and therapeutic workup.

Arrange the following steps in the most appropriate chronological sequence for the definitive diagnosis and management of this patient's condition.

  1. 1Screen for a monoclonal protein using serum and urine immunofixation and a serum free light chain assay.
  2. 2Obtain a tissue biopsy (e.g., abdominal fat pad) and apply Congo red staining.
  3. 3Determine the specific amyloid fibril precursor protein type using mass spectrometry or immunohistochemistry.
  4. 4Initiate clone-directed systemic chemotherapy (e.g., bortezomib, cyclophosphamide, dexamethasone).

Cevap

The correct sequence is: (1) Screen for a monoclonal protein, (2) Obtain a tissue biopsy for Congo red staining, (3) Determine the specific amyloid fibril type, and (4) Initiate clone-directed systemic chemotherapy.
The standard diagnostic pathway for suspected AL amyloidosis begins with non-invasive identification of the monoclonal protein burden (immunofixation and SFLC). This is followed by histologic confirmation of amyloid deposition (tissue biopsy with Congo red stain). Crucially, the amyloid MUST then be typed (via mass spectrometry or immunohistochemistry) to definitively differentiate AL from ATTR or AA types, as clinical presentations can overlap (especially cardiomyopathy). Only after AL typing is confirmed can clone-directed chemotherapy be safely and appropriately initiated.

Adım Adım Çözüm

1
Recognize the clinical syndrome of AL (Primary) Amyloidosis.
The patient has pathognomonic signs of AL amyloidosis, including periorbital purpura, macroglossia, restrictive cardiomyopathy, and nephrotic syndrome.
Identifying the clinical pattern sets the pre-test probability and dictates the need for a specific diagnostic algorithm targeting a plasma cell dyscrasia.
2
Screen for the underlying abnormal protein.
Order serum and urine immunofixation electrophoresis and a serum free light chain (SFLC) assay.
AL amyloidosis is caused by a plasma cell clone producing monoclonal light chains. This non-invasive screening is highly sensitive and establishes the presence of the suspected dyscrasia.
3
Confirm tissue deposition of amyloid.
Perform an abdominal fat pad aspiration or target organ biopsy with Congo red staining.
A positive Congo red stain demonstrating apple-green birefringence under polarized light is the gold standard to confirm the presence of amyloid tissue deposits.
4
Type the specific amyloid fibril.
Use mass spectrometry or specific immunohistochemistry on the biopsied tissue.
Congo red positivity only confirms 'amyloidosis'. It does not differentiate AL from ATTR (transthyretin) or AA amyloidosis. Typing is strictly required before initiating therapy.
5
Initiate definitive therapy based on the typed fibril.
Start clone-directed systemic chemotherapy (e.g., bortezomib, cyclophosphamide, dexamethasone).
Once AL amyloidosis is confirmed and typed, chemotherapy is used to eradicate the offending plasma cell clone and halt the progression of organ damage.

Anahtar Kavram

Diagnostic and therapeutic algorithm for Primary (AL) Amyloidosis.
Bu soruyu puanla

Konular

Hematology and Oncology

Bu konudan daha fazla soru