Prurigo chronica multiformis is a commonly used diagnostic designation for a peculiar subtype of prurigo in Japan, although the disease entity might not be well-recognized in other countries. Experts approved by the Japanese Dermatological Association attempted to build a common consensus on prurigo chronica multiformis, agreeing that it is a unique and important disease entity in elderly patients. Skin lesions are characterized by intensely pruritic, edematous, urticarial papules, or small macules, which gradually become solid papules/small nodules. The papules tend to aggregate and occasionally coalesce into polygonal lichenified plaques. The most commonly affected sites are the lower abdomen and lower back, although the chest, thighs, and upper back might also be involved. Common histopathological features of prurigo chronica multiformis include infiltration of lymphocytes and eosinophils in the upper dermis, with minimal epidermal changes. Basophil infiltration is also observed. The epidemiological incidence, differences in clinical manifestations by geographical location, and disease placement among other forms of prurigo and/or related skin diseases need to be further elucidated. Dermatologists should be aware of the clinical characteristics of prurigo chronica multiformis.

Helicobacter pylori is a gram-negative, flagellate, microaerophilic bacterium identified for the first time about 30 years ago, as a pathogenic factor of gastritis and peptic ulcer. Soon after, it was linked to several gastrointestinal and extra-gastrointestinal diseases (hematological, cardiovascular, neurological, pulmonary and ocular diseases, obesity, diabetes mellitus, growth retardation and extragastric MALT lymphoma). Association and possible cause-effect correlation with H. pylori infection were suggested in diseases of dermatological interest such as chronic urticaria, rosacea, Henoch-Schoenleins purpura, idiopathic thrombocytopenic purpura, cutaneous and oral lichen planus, atopic dermatitis, recurrent aphthous stomatitis, systemic sclerosis, psoriasis, Sjögrens syndrome, Behçet's disease, pruritus, alopecia areata, primary cutaneous marginal zone B-cell lymphomas, vitiligo, chronic prurigo, multiformis, prurigo nodularis, leukocytoclastic vasculitis, prurigo pigmentosa, eczema nummulare, primary cutaneous MALT-type lymphoma, sublamina densa-type linear IgA bullous dermatosis, Sweet's syndrome, cutaneous T-cell pseudolymphoma and pemphigus vulgaris. A critical review of the literature up to May 2017 shows clear evidence of H. pylori involvement only for some of the above purported associations, while in the majority of cases data appear contrasting and/or obtained on a not adequately large study population. Further clinical and laboratory research, with more adequate methodological and statistical basis, is required to assess the actual existence and relevance of many purported associations, as well as the possible role of H. pylori and the underlying pathogenic mechanisms.

In order to understand the pathogenic relationship between Helicobacter pylori (H. pylori) and skin diseases, we examined the serum levels of IgG antibody against H. pylori and then performed gastroscopic examinations in Japanese patients with chronic skin diseases. These H. prylori-positive patients were treated with antibacterial eradication therapy, and therapeutic efficacy was evaluated. A total of 198 patients who were resistant to conventional therapies were randomly selected. They included 50 cases with chronic urticaria, 32 with pruritus cutaneous, 74 with atopic dermatitis, 15 with nummular dermatitis, 17 with prurigo chronica multiformis, 6 with psoriasis vulgaris, and 4 with erythroderma. Positive anti-H. pylori antibody was detected in 102 out of these 198 patients; more than half of the ones with chronic urticaria, pruritus cutaneous, nummular dermatitis, and prurigo chronica multiformis had positive antibodies. Gastroscopy was then performed in 48 cases with positive antibodies. Eradication therapy was effective in 60% of the patients with chronic urticaria, in 58% with pruritus cutaneous, in 54% with nummular dermatitis, and in 50% with prurigo chronica multiformis. In chronic skin diseases, persistent infection with H. pylori may be an eruption trigger and may cause deterioration of the disease into an in tractable and chronic form.

On the basis of the clinicopathologic and causative characteristics, one can separate an erythema multiformis spectrum from a toxic epidermal necrolysis (TEN)-Stevens Johnson syndrome which is a drug induced disease. Despite a well-known clinical aspect, several cutaneous diseases may be mistaken for TEN. Responsible drugs are sulfonamides anticonvulsants, and nonsteroidal antiinflammatory drugs--patients infected with HIV are at a higher risk of developing TEN. Pathogenesis includes abnormal drug metabolism and cell mediated immune keratinocyte apoptosis. Treatment relies on symptomatic management and so-called specific treatments including steroids are probably harmful.

Clinical and laboratory tests were used to evaluate fourteen patients with senile erythroderma following eczema, and the results were compared with those from four patients with psoriatic erythroderma, two with Sézary syndrome, and twelve with prurigo chronica multiformis or nummular dermatitis. Characteristic laboratory findings included elevated serum squamous cell carcinoma-related antigens (SCC-RAg), high lactate dehydrogenase (LDH), peripheral-blood eosinophilia, and a decreased peripheral blood lymphocyte percentage. Following treatment, titers of SCC-RAg and LDH resumed normal levels with remission. In patients with senile erythroderma following eczema, serum IgE was quite high and varied but, in a few instances, was within the normal range. SCC-RAg and LDH may thus be considered useful as markers for evaluating disease conditions of the skin of patients with senile erythroderma following eczema.

Circulating immune complexes (C.I.C.) were investigated in 244 patients with various skin diseases and 100 healthy subjects. C.I.C. were detected by the PEG-C4 assay, firstly proposed by Digeon et al. using the precipitation by polyethylene glycol (PEG 3,5 p. 100) and the determination by laser nephelometry of complement component C4 in sera and in precipitates. The percentage of C4 precipitated and of positive subjects were significantly increased in numerous cutaneous diseases: systemic lupus erythematosus, scleroderma, pemphigus, bullous pemphigoid, dermatitis herpetiformis, psoriasis, contact dermatitis and lichen planus. Two cases of dermatomyositis, 3 cases of post herpetic erythema multiformis and 2 cases of Kaposi-Juliusberg syndroma were also positives but no definite conclusion can be given because of the few patients tested. On the contrary, the values of precipitated C4 are normal in most cases of atopic dermatitis (the method does not detect IgE-C.I.C.) scabies, porphyria cutanea tarda, cutaneous epithelioma and discoid lupus. In chronic urticaria and in mycosis fongoides the mean values of precipitated C4 are significantly increased but the number of positive subjects is low and the significance of these results is uncertain because of the wide range of the values. The results of the present study are compared with the literature data. The value of C.I.C. determination in determining the evolutivity of skin diseases and their possible role in pathogenesis are discussed.