Pacinian neuroma is a localized hyperplasia of pacinian corpuscles. It usually follows trauma and presents as a localized painful mass on the digits. Microscopically, it shows an increase in the size and number of pacinian corpuscles. The adjacent nerves often show degenerative changes and fibrosis. Pacinian neuromas can be distinguished from normal pacinian bodies by their size (usually greater than 1.5 mm). This image of pacinian neuroma from a digit shows a cluster of pacinian corpuscles in the lower left. Case courtesy of: Vishwas Parekh, MD, University of Pennsylvania, Philadelphia, PA.