Rare nemaline myopathy (a case report)

Introduction Nemaline myopathies (NM) are a group of neuromuscular diseases, the distinctive histological feature of which are nemaline rods in myosymplasts. The purpose of this work is to describe the morphology of a rare form of primary nemaline myopathy that progresses in adulthood. Material and methods The surgical material of the paravertebral muscles of a 51-year-old patient with scoliotic deformity at the level of L4-S1, who was repeatedly operated on to correct spinal deformity due to neurological disorders, was studied. Paraffin sections were stained with hematoxylin-eosin, according to Masson, using the Ptah method, studied using a 3DHISTECH Pannoramic MIDI II BF scanning microscope to digitize preparations using Whole slide imaging technology in two modes: Single layer mode and Extended focus (3DHISTECH, Hungary). Results In the fragments of the altered muscle tissue, filamentous structures of nemaline bodies in myosymplasts were identified, which were located diffusely-dotted throughout the sarcoplasm or formed clusters of various configurations. There was an increased variability in the diameters of muscle fibers, internal nuclei, myosymplasts altered by contraction and with signs of myophagy, patterns of gradual replacement of muscle fibers by adipocytes, massive fatty degeneration of fibers, and fibrosis of the interstitial space. Intramuscular nerve trunks showed signs of complete involution; fibrous perineurium was preserved, and there were single nerve fibers; neuromuscular spindles were distinguished by an enlarged connective tissue capsule. The vessels of the arterial flow had signs of fibrosis and obliteration of the lumen; the vessels of the venous bed were tortuous. Discussion Due to a large number of genes responsible for NM, genetic search can be difficult and is effective only in 50 % of cases. It has been established that nemaline bodies can be distributed diffusely or form clusters of irregular shape, more often subsarcolemmal and characteristic of small fibers. In the presented clinical case, nemaline bodies were observed over the entire area of the fibers and were characteristic of myosymplasts of various sizes. Conclusion The histopathological study of the paravertebral muscles established the neuromuscular nature of the disease, being nemaline myopathy that progressed in adulthood and had not been diagnosed at previous stages of treatment.