Dados do Trabalho

Título

A rare case of early-onset Inclusion Body Myositis (IBM): a case report

RESUMO

Case presentation: female, 37 years old, from Salvador/Bahia, with crural paraparesis for 10 years. She perceived difficulty in climbing stairs and today she walks with bilateral support. In the last two years, she also presented upper limbs weakness, distal, more evident when trying to open pots. Hypotrophy of the quadriceps and on the ventral surface of the forearms was identified, as well as reduced muscle strength in leg extension and foot dorsiflexion and also weakness in the fingers. Myopathic gait pattern. A CPK (Creatine Phosphokinase) of 164 U/L (normal < 145) was measured. Electroneuromyography of the lower limbs with myopathic pattern. Muscle biopsy revealed rimmed vacuoles, expression of the MHC-I complex in sarcoplasmic membranes, immunophenotypic staining of membrane attack complex in sarcoplasmic membranes and capillaries, presence of CD8+ lymphocytes and presence of P62 aggregates in focal areas of the endomysium and sarcoplasm.The clinical suspicion was of Inclusion Body Myositis. The treatment started with prednisone 1mg/kg/day for 90 days, with no clinical response. The choice of not introducing any other immunosuppressants was made.
Case Discussion: Inclusion Body Myositis (IBM), an inflammatory myopathy, is a rare, slowly evolving disease common in males over 50 years of age 1,2,3 . Clinical manifestations include weakness in the quadriceps femoris muscle and ankle dorsiflexors, resulting in difficulty in walking and climbing stairs, as well as in the wrist and finger flexors 3,4,7,8,9. CPK (Creatine Phosphokinase) can be normal or increased. Anti-cN1A antibody dosage provides good specificity. On electroneuromyography, it is characteristic the presence of fibrillation and positive acute waves and increased polyphasic motor unit potentials 6,7,8,9. On muscle biopsy, the gold standard exam, it was verified the presence of endomysial infiltrate of mononuclear cells: CD8+ T lymphocytes and macrophages. A small number of myofibrils presented marginated vacuoles, a very characteristic finding in IBM 3,6,8,9. Evidence indicates that patients with IBM respond poorly to corticosteroid therapy. Other immunosuppressants can be tried in those patients who respond to corticosteroids 10,11,12,13,14.
Final Comments: IBM remains a rare and challenging entity. This is the case report of a patient who, despite being an unusual age group, had clinical and pathological findings suggestive of IBM and unresponsiveness to corticosteroid therapy.