Patient selection: usually primary amyloidosis
Clinical features:
(1) abnormal firmness of affected muscles
(2) pseudohypertrophy of the muscles, giving a muscular or athletic appearance
(3) variable presence of a palpable tumor within a muscle
(4) limb weakness that may be proximal or generalized
(5) variable concurrent macroglossia
(6) variable dysphagia or hoarseness
(7) rarely ophthalmoplegia
(8) rarely respiratory failure
(9) may be progressive despite therapy
MRI may show a reticulation of subcutaneous fat
The EMG is often nonspecific but may show myopathic or denervation features.
The serum CK may be normal to moderately elevated.
Muscle biopsy shows:
(1) perimysial and endomysial deposition of amyloid
(2) scattered atrophy of muscle fibers
(3) variable deposition of amyoid in connective tissue
(4) variable deposition of amyloid within the walls of blood vessels
