Pityriasis rubra pilaris is a rare disease, which is included among follicular eruptions. It is well characterized from a clinical point of view. However, its etiology is unknown and a well defined biological or pathological marker lacks. From a clinical point of view, pityriasis rubra pilaris is characterized by palmo-plantar keratoderma, follicular keratosis and tendency to erythroderma. Psoriasis is very frequent and is easily diagnosed in the majority of cases. However, psoriasis can be rarely characterized by clinical features superimposable to those ones of pityriasis rubra pilaris, namely involvement of the palmo-plantar region, follicular keratosis and tendency to erythroderma.
Basal cell carcinoma is a tumor deriving from keratinocytes. It is characterized by a differentiation that is reminiscent of keratinocytes of the basal layer. Basal cell carcinoma is a low malignancy tumor and only exceptionally gives raise to metastases. It affects subjects even with dark phototype, mainly on photoexposed areas, but even on other sites, starting from the third decade of life. Exceptionally, basal cell carcinoma affects subjects under 20 (4, 9, 17, 29), almost always due to predisposing factors. The latter include xeroderma pigmentosum, sebaceous nevus, nevoid basal-cell carcinoma syndrome, and chronic muco-cutaneous candidiasis. (...).
The antihistamines are the drugs most widely prescribed in pediatric dermatology, although not always rationally. Interestingly enough, the antihistamines are usually prescribed in children because of effects that, on the other hand, are considered as unwanted side effects in adults. As a matter of fact, we can consider the sedative effect. To overcome the latter many studies were carried out, leading to the synthesis of second-generation antihistamines, which are devoid of sedative effect. We can also consider the increased appetite, which led to excessively prescribe cyproheptadine. The antihistamines are rationally prescribed in urticaria, especially acute urticaria, and in the most severe cases of mastocytosis. On the other hand, their usage is debated in atopic dermatitis and in the itchy disorders due to other causes. Their debated activity in these disorders is probably related to an effect, which is usually considered a side effect of the first-generation antihistamines, namely the sedative effect on the central nervous system (12). (...).
Nevus depigmentosus (ND) was first reported by Lesser in 1884 (13). Present at birth or from the first years, ND is a nevus malformation persisting indefinitely. Although not yet clarified from a pathogenetic point of view, ND is well defined from a clinical point of view and characterized by a decreased pigmentation as compared with the healthy surrounding skin. Its pigmentation is decreased, but not lacking, as shown by its color, which is less light as compared with the color of vitiligo and piebaldism, and by the possibility of getting tanned.
Localized cutaneous scleroderma is the most frequent connective tissue disease of childhood. Its lesions are often distributed along a cutaneous segment and are characterized by an initial inflammatory phase. The latter is followed by a characteristic hardening of the skin. In the well developed lesion a peripheral inflammatory ring often persists around the central sclerotic plaque. Also unilateral nevoid telangiectasia is characterized by a segmental distribution. It is remiscent of port-wine stain, due both to its metameric distribution and color of the lesions. However, unilateral nevoid telangiectasia is acquired, often in the first decade of life, whereas port-wine stain is present since birth.
Eruptive angioma (EA) is a benign proliferation of angiopoietic tissue rapidly growing in a few weeks till causing erosion of the epidermis and bleeding. In the past its most frequent synonym was pyogenic granuloma, whereas the most recent term of “lobular capillary hemangioma” was proposed by Mills et Al. (17). Since 1982, starting from the report of Mulliken and Glowacki (18) there were some attempts of classification of lesions, which in the past had been all included in the chapter of angioma. These attempts are laudable because they try to introduce pathological and functional criteria, in contrast with the previous classification using exclusively clinical criteria. In a new classification (24) all the previously known angiomatous lesions are classified into the categories as follows: hamartomas, malformations, dilatations of preexisting vessels, and proliferations, the latter being in turn subdivided in hyperplasias, benign neoplasms and malignant neoplasms. Unfortunately, the borders between the various entities, for instance between hyperplasia and benign neoplasm or even between benign and malignant neoplasm (23) are not always well defined as it would be necessary for a classification, because nature does not jump.(...).
Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited disease due to a mutation of the gene codifying for collagen VII, which is the most important component of the anchoring fibrils. The consequent defect of the anchoring fibrils, which are necessary for the connection between epidermis and dermis, is responsible for the dermo-epidermal cleavage and therefore for blisters following even trivial traumas. Due to the collagen defect, blisters heal with atrophic scars, justifying the name of the disorder. Epidermolytic ichthyosis or congenital erythrodermic bullous ichthyosis (BI) is an inherited disorder due to a mutation of the gene codifying for keratins 1 and/or 10. The consequent defect of the keratin manifests itself with microscopic (epidermolytic hyperkeratosis) and ultramicroscopic alterations of the epidermis and, clinically, with blisters and scaling erythroderma. Both the disorders can be present at birth with blistering lesions, which are especially localized on sites of trauma, therefore requiring a differential diagnosis.
The diseases of the mouth involve different specialists. In some very big towns there is a specific specialist of the mouth. However, in most cases the diseases of the oral mucosa are treated by dermatologists, because many disorders of the skin are associated with simultaneous involvement of the oral mucosa. Although more interested in the disorders of the teeth, even the dentist observes such disorders. When a disease is simultaneously responsible for lesions of the skin and of the oral mucosa, the diagnosis should be done taking into account the skin lesions, before looking at the oral lesions. As a matter of fact, the mouth, together with nails, hair and, at a lesser extent, palmoplantar region and extensor aspect of the elbows and knees, are sites where the diagnosis is more difficult, because here there are peculiar characteristics, namely characteristics of the site, that obscure the characteristics of the skin disorder. Particularly, the lesions of the mouth are characterized by a whitish appearance due to soaking.
Hemangioma and port-wine stain are two distinct entities from the clinical and evolutive point of view. However, they possibly share a common pathogenesis, as supported by reference to other disorders, the higher frequency of both conditions in premature babies and, finally, the clinical course of the precursors of hemangioma and of metameric hemangioma.