The spectrum of muscle pathologies: Three decades of experience from a reference laboratory in Saudi Arabia

Background: When investigating patients with a suspected neuromuscular disorder, a muscle biopsy is considered an instrumental tool to reach a definitive diagnosis. There is a paucity of publications that assess the diagnostic utilization and yield of muscle biopsies. We intend to present our experience in this regard over an extended period of more than three decades. Methods: This is an observational retrospective cohort study in which we collected pathology reports for muscle biopsies diagnosed at our reference lab between 1986 and 2017. Results: We identified a total of 461 cases of muscle biopsy performed, which fulfilled the inclusion criteria. Pediatric cases defined as <= 14 years of age constituted a significant proportion of cases (n = 275, 60%). Normal biopsies were reported in 27% of cases (n = 124), and in 4%, the biopsies were non-diagnostic. The most common pathologies reported were non-specific myopathy (n = 72, 16%), dystrophy (n = 71, 15%), and neurogenic disorders (n = 60, 13%). Conclusion: In conclusion, the muscle biopsy will continue to play a crucial role, as a gold standard or as a complementary investigation, in the diagnosis of certain neuromuscular disorders. Increasing the yield and accuracy of muscle pathology should be the main concern and priority to neuropathologists reporting muscle biopsies. In addition, utilizing next-generation sequencing and other molecular techniques have changed the location of muscle biopsy in the algorithm of the diagnosis of neuromuscular disorders. This paper is an urgent call to establish the Saudi Neuropathology Society and the muscle pathology and neuromuscular disorders registry.