Lichen planus pemphigoides (LPP) is a rare autoimmune blistering disease. It appears to be combination of lichen planus and bullous pemphigoid. We describe four new cases of LPP and discuss the epidemiological, clinical, pathological, and therapeutic features of this singular association through a review of the 74 published cases within the English literature. We report four cases of LPP (three women aged respectively 47, 51, and 53 years old, and a 53-year-old man). All patients presented with bullae on lichenoid and normal skin, predominately on the extremities. The diagnosis was confirmed by immunohistological findings. Our patients were treated with oral corticosteroids with a good response. Our review of the literature of 78 cases of LPP (65 adults and 13 children) showed that it involved adults (mean age: 54 years), with a slight female preponderance. A mean lag time between LP and the development of LPP was 8.3 months. LPP is characterized by developing blisters on lichenoid lesions and on uninvolved skin with more acral distribution of bullous lesions. Involvement of palms and soles was more frequent in children. The diagnosis is based on pathological and immunological confrontation. LPP is usually idiopathic, but some cases were reported in association with various drugs. There have also been reports of association with internal malignancy. Most cases of LPP are successfully treated with systemic corticosteroids. In most cases, the prognosis was good.

Pemphigus are rare but informative models of organ-specific autoimmune diseases, resulting from the interplay of environmental, genetic and stochastic factors. There are many arguments to consider that pemphigus have a genetic basis involving, as many other autoimmune diseases, several different genes with additive or synergistic effects. So far, the unique strategy used to identify the contributive loci has been direct analysis of candidate genes through conventional case-control association studies. The major histocompatibility complex in particular the class II locus was demonstrated to be associated with pemphigus with a high rate of replicability. The progresses in the understanding of pemphigus physiopathology and the development of new molecular tools offer new perspectives to unveiled the genetic basis of this group of autoimmune blistering diseases, as shown by recent studies of candidate genes expressed at different levels of the autoimmune process.

competent cutaneous permeability barrier (Cameron et al., 2007). In this regard, decreased expression of elongases in AD-like skin lesions and subsequent failure to adequately produce long FAs might have contributed to the depletion of the ceramide[NS] species with very long-chain FAs that are more essential to CBF than those with shorter FAs (Janusova et al., 2011). Interestingly, peroxisome proliferator activator receptors, liver X receptor, and the sterol regulatory element binding protein signaling pathways, which are important in the transcriptional regulation of elongases, also have critical roles in epidermal barrier function (Elias, 2005), which may be in line with the alteration of elongase and disrupted CBF in AD-like skin lesions.In conclusion, we found that the profiles of FA lengths of ceramide species are different in AD-like skin lesions, i.e., the ceramides with very long FAs (XC24) decreased whereas those with shorter FAs (pC22) increased in AD-like skin lesions. The expression levels of elongases were downregulated in AD-like skin lesions, which might have impaired the synthesis of ceramide species with very long FAs and tilted the balance toward the dominance of ceramide species with shorter FAs over those with longer FAs in the SC of AD. These results suggest that the alteration in elongases as well as in the profile of FA lengths of ceramides could be useful for the diagnosis of AD. More importantly, the modulation of elongases might be effective in repairing damaged CBF in AD.