A case of isolated plexiform neurofibroma in a patient with myasthenia gravis

Abstract

We report a case of an isolated plexiform neurofibroma occurring in a patient with myasthenia gravis. A 48-year-old man presented with asymptomatic skin-colored nodules on the tip of his 4th finger. Microscopically, a plexiform neurofibroma was identified located in the dermis that appeared to originate from small superficial nerves. He had a 20-year history of treated myasthenia gravis; otherwise, his personal and family histories were unremarkable. Given that myasthenia gravis is a disorder of the peripheral nerves, plexiform neurofibromas could be associated with myasthenia gravis. However, the development of an isolated plexiform neurofibroma in a case of myasthenia gravis has not yet been reported. The occurrence of a neurofibromas in a patient with myasthenia gravis suggests a link in the pathogenesis of these two diseases.

Keywords: Isolated; Myasthenia gravis; Plexiform neurofibroma.

Fig. 1

0.7×0.5 cm sized rubbery nodule on right fourth finger tip.

Fig. 2

(A) Well circumscribed numerous nerve fascicles with irregular configurations embedded in cellular matrices (H&E stain, ×40). (B) Spindle shaped cells with wavy collagen fibrils in myxoid stroma (H&E stain, ×100). (C) Numerous cells of the fascicles present intensive positivity for S-100 protein (S100 stain, ×200).