Collagen

There are multiple types of collagen, divided into two major classes:

Fibril-forming

type I: the major type in dermis, tendons and bone

type II: found in cartilage

type III: found in connective tissue and forms the major component of reticulin

type V: found in the desmoplastic stromal reaction to tumours.
Non-fibril-forming

type IV: together with laminin, forms the major constituent of basement membrane.

type VII: found in the basement membrane underlying combined epithelia.

Immunohistochemical expression

Diagnostic utility

Type IV is useful in the distinction of in-situ from (micro)invasive carcinoma. In soft tissues, complete basement membranes form around endothelial, smooth muscle and Schwann cells: antibodies against laminin and collagen IV are useful for the identification of these lineages.

Type VII is associated with squamous differentiation of carcinomas.

References

¹Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 70

This page last revised 21.12.2001.