Claudins

The claudins are a family of about 18 proteins which are components of the tight junction (Latin claudere, to close). They are found with other components including occludin and junctional adhesion molecule, and interact with scaffold proteins, ZO-1, ZO-2 and ZO-3. The claudins constitutes a variable component, with specific claudins being associated with specific tissues.

Immunohistochemical expression

• Claudin-1; epithelia and perineural cells. There is disagreement as to the rate of positivity in perineuromas.

A number of tumours which form the differential from perineuromas are negative for Claudin-1:

	Claudin-1
perineuroma	11/12 (staining is membranous: >50% of cells in 7/12 cases, 25-50% of cells in 3/12 cases, <25% of cells in 1/12 cases)1, 22/76 (soft tissue perineuromas: 14 cases staining of more than 50% of cells, 3 cases staining of 26-50% of cells, 4 cases staining of 5-25% of cells, 1 case staining of less than 5% of cells.)2
dermatofibrosarcoma protuberans	0/71
low-grade fibromyxoid sarcoma	0/81
desmoplastic fibroblastoma	0/31
fibromatosis	0/71
neurofibroma	6/9 (a significant number of cells, mainly peripheral, with long cytoplasmic processes, thought to be perineural in origin were positive.)1
Schwannoma	3/5 (capsular cells in three cases and perivascular cells in one case were positive)1

• Claudin-3; lung and liver epithelium¹

• Claudin-5; endothelium¹

Diagnostic utility

• Claudin-1, with EMA (positive) and S-100 (negative) in the diagnosis of perineuroma.

References

¹ Folpe, A.L., Billings, S.D., McKenney, J.K., Walsh, S.V., Nusrat, A. and Weiss, S.W. Expression of claudin-1, a recently described tight junction-associated protein, distinguishes soft tissue perineurioma from potential mimics. Am J Surg Pathol 2002;26:1620-6.

² Hornick JL,Fletcher CD. Soft tissue perineurioma: clinicopathologic analysis of 81 cases including those with atypical histologic features. Am J Surg Pathol 2005; 29:845-58

This page last revised 28.8.2005.

©SMUHT/PW Bishop