Decrease of E-cadherin expression in canine cutaneous histiocytoma appears to be related to its spontaneous regression.

Background: Canine cutaneous histiocytoma (CCH) is an epidermotropic tumour of Langerhans cells, most frequent in young dogs, which undergoes spontaneous regression.
Materials and Methods: E-cadherin immunoexpression was analysed in ninety-three CCH, categorized according to Cockerell and Slauson (1976) criteria into four histological groups, representing different stages of tumour regression.
Results: All tumours expressed membranous E-cadherin both in keratinocytes, and in tumoural cells and no differences were noted among the histological groups analysed. However, the intensity of the E-cadherin immunolabeling decreased in the presence of lymphoid infiltration and varied significantly among the groups considered (p<0.0001).
Conclusion: This study strongly suggests a down-regulation of E-cadherin expression in CCH pathogenesis and progression. The loss of E-cadherin expression might represent an activation/ maturation process of the tumoural cells constituting a switch for CCH regression.