Sporadic Late-Onset Nemaline Rod Myopathy: An Interesting Case

Sporadic late-onset nemaline rod myopathy is a rare, acquired, sub-acute, adult-onset myopathy characterized by proximal muscle weakness and nemaline rods in the myofibers. In contrast to its congenital form, the prevalence in adult population is comparatively rare. Herein, we report a case of 60-year-old male who presented with insidious onset proximal muscle weakness with myopathic pattern on electromyography. Histopathological examination showed type 1 and 2 muscle fiber atrophy with minimal chronic inflammatory cell infiltrate. Modified Gomori trichrome staining revealed granular deposits in the myofibers. Ultrastructure examination showed numerous nemaline rods in the myofibers; hence, the diagnosis of sporadic late-onset nemaline myopathy was rendered. Its association with monoclonal protein has been reported in the past. One should be aware of this rare entity as without correct diagnosis, there can be treatment failure and unfavorable outcome.