Morphological and Histochemical Changes in Muscle Biopsies of Myasthenia Gravis with Atypical Clinical Presentation

The morphological and histochemical changes in muscle biopsies from 6 cases with myasthenia gravis (MG) were studied, The patients were misdiagnosed at the initial presentation, however they were all proved later by either histochmical and serological tests or improvement on mestinone therapy to have MG. Here, the histomorphological and histochemical changes that were seen in muscle biopsies of MG with atypical clinical presentation were the followings: atrophy of type II fibers; predominance of type I fibers; increased NADH staining at the neuromuscular junction (NMJ). The most consistent finding is marked reduction in acetylcholinesterease (AChE) activity at the end plates in all cases. The results of this study suggest that histochemical and acetyl cholinesterase stains, in combination with clinical assessment can help to identify unsuspected cases of MG.