Lichenoid infiltrate

Lichenoid Infiltrate                         See DX Path for details of the conditions below



The lichenoid reaction pattern is one of the Interface patterns of damage at the Dermoepidermal junction. There is a dense infiltrate of lymphocytes often obscuring the DEJ with basal vacuolar change.The overlying epidermis is usually acanthotic and there is hyperkeratosis but parakeratosis is only seen in a lichenoid keratosis.

The reaction is mediated by T cells. through both a Type 2 and Type 4 immune reaction. The underlying cause may be viral or drug cytotoxicity or autoimmune reactions to self proteins in the epidermis. Some of the cytokines produced will cause epidermal proliferation with a prominent granular layer or some basal squamatisation of the keratinocytes.

Histological changes at the dermal/epidermal junction can involve the epidermis and for this reason disorders that are primarily due to an immune attack of lymphocytes at the dermal/epidermal junction may give an epidermal reaction. Most conditions will be covered by the Red Scaly diseases mnemonic PMs PETAL with the L being extended to include Lichenoid keratosis, Lichen nitidus , Lichen sclerosus and Lichen stiatus.



Classic conditions in this category include lichen planus, lupus erythematosis and erythema multiforme. There are variants on this such as fixed drug reaction, graft versus host reaction and some of the other collagen diseases that also are associated with damage to the dermal/epidermal junction but generally in these disorders the epidermal damage is minimal and they still present as red non scaly diseases.