Pacinian corpuscles, also known as Vater-Pacini corpuscles or lamellar corpuscles, are pressure-sensitive nerve endings in the skin. They are the largest mechanoreceptors in the body and are important to recognize as they may be mistaken for pathology.
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Gross anatomy
Pacinian corpuscles are seen as ovoid structures in the hands more than the feet, specifically near the digital tips, midpoints of all phalanges (middle phalanges less), metacarpophalangeal/metatarsophalangeal joints, and metacarpals/metatarsals. Each corpuscle measures ~1 mm and arises in the volar subcutaneous fat 2,3,7.
Innervation
In the hand, each Pacinian corpuscle is innervated by a small neural twig from an adjacent digital nerve.
Histology
Histologically, Pacinian corpuscles are fluid-filled capsulated structures mainly consisting of water organized into concentric lamellae, hence their alternative monicker lamellar corpuscle. Centrally there is a non-myelinated terminal axon 2,7.
Radiographic features
Pacinian corpuscles have been seen on 3 T (cadavers only) and 7 T MRI 3. A study in 2018 using high-frequency (22 MHz) ultrasound, visualized the corpuscles in 100 healthy volunteers, as well as in cadaveric hands; in the latter histological correlation was used for confirmation. The 3 T MRI study, also tried to see the corpuscles that had been visible on MRI, on ultrasound using a 13 MHz transducer but was unable to appreciate them 8.
Ultrasound
- hypoechoic foci in the subcutaneous soft tissues in close proximity to digital vessels and nerves, ~3 mm deep to skin surface 8
MRI
- T1: isointense to skeletal muscle 3
- T2: hyperintense nodules in close proximity to the tips of all digits (hands > feet), volar aspect of all metacarpophalangeal joints, and proximal phalanges, with fewer numbers adjacent to the middle phalanges 3,7
Radiology report
Pacinian corpuscles are a normal finding and may not need to be noted unless associated pathology is suspected.
Related pathology
- Pacinian corpuscular neuromas: rare cases 3
- hyperplastic Pacinian corpuscles: rare 6
History and etymology
Pacinian corpuscles were named after Filippo Pacini (1812-1883), Professor of anatomy at the University of Pisa, who wrote about them in 1840 4. Pacini is also celebrated for the first description of Vibrio cholerae, the causative organism of cholera, in 1854 4. However, they were first described by Abraham Vater (1684-1751) a German pathologist in Wittenberg in 1717. Hence the corpuscles may be referred to by alternative names, such as Pacinian-Vater corpuscles. Of course, Vater is best remembered for his description of the hepatoduodenal ampulla, i.e. ampulla of Vater in 1720 4.
Corpuscle (or corpusculum), sounds and looks old-fashioned to modern eyes. Corpusculum is the diminutive form of corpus, the Latin for body 5. Corpuscle is used in anatomy to refer to any small body or mass of tissue. Historically it was also commonly used for cells themselves, e.g. white blood corpuscles 5.
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