Neuroma Pathology: The Role of Histological Analysis

Histological analysis of biopsied nerve can aid in neuroma diagnosis, as well as research efforts to understand the biology of neuroma. Routine histological diagnosis of neuroma often utilizes microscopy employing chemical stains, such as hematoxylin and eosin (H&E) or osmium tetroxide with toluidine blue counterstain. Microscopically, these techniques reveal neuroma to consist of chaotically arranged axons with numerous sprouts, normal Schwann cells, and an expanded extracellular matrix with numerous fibroblasts. The use of osmium tetroxide in processing and staining offers the potential to perform detailed electron microscopy, as well as quantitative analysis of nerve morphology, which can distinguish unmyelinated axons with greater resolution. Alternatively, molecular histological techniques, such as immunohistochemistry, can also identify neuroma and offer growing opportunities for research investigation. A basic spectrum of antibodies that can be included to identify essential components of nerve include PGP 9.5, neurofilaments, beta-III tubulin, S100β, collagens, and laminin. Additionally, molecular histology can distinguish motor versus sensory axons, as well as differences in protein expression in neuroma, such as markers associated with symptomatic vs asymptomatic neuroma, and uncover new biomarkers and molecular targets for therapeutics.