Brain Pathology Case of the Month - June 2012

DIAGNOSIS

Pacinian hyperplasia ("Pacinioma", pacinian neuroma) associated with meningoradiculocele.

DISCUSSION

Dysraphic conditions of the spine resulting from non-closure of the neural tube comprise a wide spectrum of different types of malformations. In meningoradiculocele the nerve roots are components of the herniated cystic structure. The material that usually is submitted to histological examination may contain various amounts of soft tissue (including adipose tissue) and meninges (1, 2, 5, 6). Nerve structures are frequently encountered and may vary from easily identifiable large myelinated nerve trunks to small nerve fascicles with moderately increased numbers of fibres compared to those normally present. Very rarely, these structures may present "neuroma-like" features with proliferation of Schwann cells, or pacinian corpuscles hyperplasia with "onion bulbs" features (1, 2, 5, 6). Hypertrophy and hyperplasia of pacinian corpuscles is a rare condition and occur mainly in adults (4, 7, 8). The preferential site of occurrence is the hand but some deep seeded localisations have been described (3, 8). Although history of local trauma was often reported, the pathogenesis of such a lesion is still unclear (8). Histologically, pacinian hyperplasia does not form large tumor-like masses. The corpuscles have a normal structure but are increased in size and number. Sometimes they are dystrophic, with several lamellar bodies within a single capsule.

In the differential diagnosis, other lesion consisting of intraneural proliferation of perineural-like cells may be considered. Intraneural perineurioma is characterized by a tumoral, fusiform segmental growth of nerve trunks and histologically composed by densely packed, EMA-positive perineurial cells which proliferate in pseudo-onion bulb whorls around thin axons (9). In our case, the areas showing densely packed cells could resemble a "perineurioma-like" architecture: however, the combined EMA negativity and S-100 positivity indicate that these elements are reactive Schwann cell rather than real perineural cells.

Other nerve sheaths lesions or tumors, including neurofibroma, schwannoma and traumatic neuroma, may present a perineural onion bulb-like structures but pure pacinian differentiation associated to nerve sheath tumors have not been demonstrated (3, 8).

In conclusion, pacinian hyperplasia may be rarely encountered in sample obtained from surgery for spina bifida malformations, and has not to be confused with other more common neoplastic lesions affecting the spinal cord region.

Acknowledgments: The authors want to thank Dr. R. Bickenbach (Bonn) for the prenatal ultrasound data.

REFERENCES

  1. Bale PM. Sacrococcygeal developmental abnormalities and tumors in children. (1984) Perspect Pediatr Pathol; 8: 9-56.
  2. Berry AD, Patterson JW. (1991) Meningoceles, meningomyeloceles, and encephaloceles: a neuro-dermatopathologic study of 132 cases. J Cutan Pathol 18: 164-177.
  3. Fletcher CD, Theaker JM (1989) Digital pacinian neuroma: a distinctive hyperplastic lesion. Histopathology 15: 249-256.
  4. Fraitag S, Gherardi R, Wechsler J. (1994) Hyperplastic pacinian corpuscles: an uncommonly encountered lesion of the hand. J Cutan Pathol; 21: 457-460.
  5. Kojc N, Korsic M, Popovic M (2006) Pacinioma of the cauda equina. Dev Med Child Neurol 48: 994-996.
  6. Lellouch-Tubiana A, Zerah M, Catala M, Brousse N, Kahn AP (1999) Congenital intraspinal lipomas: histological analysis of 234 cases and review of the literature. Pediatr Dev Pathol 2: 346-352.
  7. Reznik M, Thiry A, Fridman V (1998) Painful hyperplasia and hypertrophy of pacinian corpuscles in the hand: report of two cases with immunohistochemical and ultrastructural studies, and a review of the literature. Am J Dermatopathol 20: 203-207.
  8. Scheithauer BW, Woodruff JM, Erlandson RA (1997) Reactive lesions. In: Tumors of peripheral nervous system. Atlas of Tumor Pathology, Third Series, Fascicle 24, Rosai J, Sobin L (eds.), Chapter 3, pp. 41-46, Armed Force Institute of Pathology: Washington.
  9. Scheithauer BW, Woodruff JM, Erlandson RA (1997) Miscellaneous benign neurogenic tumors. In: Tumors of peripheral nervous system. Atlas of Tumor Pathology, Third Series, Fascicle 24, Rosai J, Sobin L (eds.), Chapter 9, pp. 219-228, Armed Force Institute of Pathology: Washington.

Contributed by Marco Gessi, Martina Messing-Jünger, Andreas Röhrig, Gerrit H. Gielen, Torsten Pietsch, Frank K.H. van Landeghem

International Society of Neuropathology