Clinical History
This 77-year-old patient presented with atrophy of the cranial and extremity muscles, dysphagia, and multiple falls. Past medical history includes acute lymphoblastic lymphoma, marrow lymphoblasts 30%, and pancytopenia. Upon physical exam, cachectic appearance speech fluent without dysarthria, strength: 5-/5 upper extremities, 4+/5 lower extremities, MRI lumbar spine multilevel with degenerative changes and severe canal stenosis L3-4. EMG shows myopathic units of the abductor pulses bravos, pronator tarries, triceps and deltoid muscles. Nerve conduction study showed sensorimotor neuropathy. Lab results: aldolase 5.0, ANA negative, vitamin B12 normal, BNP elevated, C-reactive protein 2.0 (High), and serum protein electrophoresis showed a weak M-protein band thought clinically not to be clinically significant.
Question:
What is the pathological process?
A. Small artery vasculitis
B. Moyamoya disease
C. Obliterative vasculopathy
D. Vascular amyloidosis
Answer:
The correct answer is D. Vascular amyloidosis.
Bonus Question:
What is the underlying etiology?
A. Aβ deposition
B. Light chain disease
C. AA amyloidosis
D. Transthyretin deposition
Answer:
The correct answer is B. Light chain disease
Vascular amyloidosis
Amyloid- abnormal aggregation of amorphous protein of multiple types (immunoglobulins, Aβ, transthyretin, AA, etc.).
- Most are fibrillary as seen by electron microscopy, but a few, like the immunoglobulin- light chains kappa and lambda may not be.
- Can deposit almost anywhere but in muscle it is usually seen around vessels.
Congo Red- nonspecific stain to detect any amyloid (stains salmon or peach-orange)
- Shows characteristic “apple-green” birefringence under crossed-polarization
- Fluoresces red under Texas red or FIT-C fluorescence microscopy
Typing amyloid
- Immuno-staining
- Here kappa restriction is demonstrated by immunofluorescence. This is most likely due to abnormal antibody shedding by the patient’s lymphoma
- Microdissection and mass spectroscopy can be used to confirm known proteins or identify unknown proteins
- Confirmed by mass spectroscopy
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