Identification of Pacinian Corpuscles in the Human Hand Using High-Resolution Ultrasound

Background/Objectives: Pacinian corpuscles are end organs complexes associated with rapidly adapting low-threshold mechanoreceptors abundant in the human hand. Pathological conditions involving Pacinian corpuscles are rare and normally appear as subcutaneous painful nodules. Diagnostics of those pathologies is usually throughout cutaneous biopsy. This study aimed to investigate whether human hand Pacinian corpuscles can be visualized using non-invasive high-resolution ultrasound. Methods: Five adult subjects were evaluated using high-resolution ultrasound following the digital nerves in the palm, and Pacinian corpuscles were identified based on their localization and morphology. Moreover, a structural, immunohistochemical, immunofluorescence associated with confocal laser microscopy and optic-densitometry was performed in palm cutaneous samples (n = 5) from the same areas as in ultrasonographic study. Results: Pacinian corpuscles were visualized within the intermetacarpal fat pads between flexor tendons and dorsal to the neurovascular bundles. They appeared as subcutaneous, oval, hypoechoic structures with an echogenic central structure which correspond, structurally, to the inner core and the outer capsule core, as demonstrated by immunohistochemistry and immunofluorescence associated with confocal laser microscopy and optical densitometry. Conclusions: Pacinian corpuscles can be identified, visualized, and counted in the human hand using high-resolution ultrasound. Furthermore, the neural and non-neural compartments of these corpuscles can be distinguished. Present results open the possibility of carrying out mapping studies of the Pacinian corpuscles of the hand as well as analyzing their size and structure under normal and pathological conditions.