[Non hypertrophic amyloid myopathy with muscular inflammation in plasma cell dyscrasia]

The case of a 41 year old woman with amyloid myopathy is reported. Clinical involvement consisted of limb girdle muscle weakness, mild scapular muscle atrophy and dysphagia. In contrast with the published cases, abnormal firmness, pseudohypertrophy of the musculature and macroglossia were absent. Muscle biopsy showed endo- and perimysial amyloid deposits but also inflammatory infiltrates. Inflammatory cells typing was studied by immunocytochemical methods and revealed a predominant T-helper cell infiltration. Free kappa light chains were present in serum and urine. Serum immunoglobulin levels were reduced. Bone marrow examination revealed mild plasmocytosis without abnormal cells. Immunofluorescence and immunoperoxidase techniques for identification of the type of amyloid fibrils showed positivity with antisera to kappa light chains. A 4-year follow-up revealed a progressive worsening of muscle weakness despite immunosuppressive treatment. No malignant plasmocytosis occurred. The unusual inflammatory muscle infiltration observed in this case may suggest an associated polymyositis.