[Multiple epidermolytic acanthomas of the genitalia]. / Hyperkératose épidermolytique génitale (acanthomes épidermolytiques génitaux multiples).

BACKGROUND: Epidermolytic hyperkeratosis presents a particular histological image common to several clinical pictures, including that of keratinopathic ichthyoses. It may also occur fortuitously in various tumoral and inflammatory lesions. It is the elementary histopathological lesion of epidermolytic acanthoma, which may either be single or multiple, and when it occurs in the genital area, is known as epidermolytic hyperkeratosis of the genitalia or multiple epidermolytic acanthoma of the genitalia. Herein, we report two characteristic cases of epidermolytic hyperkeratosis of the genitalia. PATIENTS AND METHODS: The first patient was a 50-year-old woman consulting for vulvar pain in whom clinical examination revealed the presence of multiple papules on the labia majora and minora. The second patient was a 44-year-old man consulting for verrucous lesions of the scrotum. In both cases, biopsy revealed an histopathological aspect identical with acanthosis, hyperkeratosis, changes in the keratinocytes, in which the cytoplasm contained clear vacuoles, numerous keratohyalin granules and eosinophilic bodies, resulting in a diagnosis of epidermolytic hyperkeratosis of the genitalia. DISCUSSION: Epidermolytic hyperkeratosis of the genitalia is a rare disease, occurring in middle-aged men and women, but chiefly men. The lesions found on the genital organs may be either single, or, more frequently, multiple, and are described as hyperkeratotic papules, which are also reported under the term multiple epidermolytic acanthomas of the genitalia. The aetiology is unknown; certain authors incriminate a traumatic factor; the role of human papillomavirus (HPV) has been suggested but immunohistochemical studies and molecular biology studies generally reveal no viral DNA. Where lesions cause discomfort to the patient, treatment consists of emollients combined with destruction by cryotherapy or CO2 laser. Imiquimod, calcipotriol, tacrolimus and pimecrolimus have all resulted in regression of lesions.

Management of Epidermolytic Ichthyosis in the Newborn.

Epidermolytic ichthyosis (EI) is a rare autosomal dominant genodermatosis that presents at birth as a bullous disease, followed by a lifelong ichthyotic skin disorder. Essentially, it is a defective keratinization caused by mutations of keratin 1 (KRT1) or keratin 10 (KRT10) genes, which lead to skin fragility, blistering, and eventually hyperkeratosis. Successful management of EI in the newborn period can be achieved through a thoughtful, directed, and interdisciplinary or multidisciplinary approach that encompasses family support. This condition requires meticulous care to avoid associated morbidities such as infection and dehydration. A better understanding of the disrupted barrier protection of the skin in these patients provides a basis for management with daily bathing, liberal emollients, pain control, and proper nutrition as the mainstays of treatment. In addition, this case presentation will include discussions on the pathophysiology, complications, differential diagnosis, and psychosocial and ethical issues.

Molecular mechanism of kallikrein-related peptidase 8/neuropsin-induced hyperkeratosis in inflamed skin.

BACKGROUND: Hyperkeratosis and acanthosis occur in inflamed skin. Proliferation and differentiation of keratinocytes are important processes during epidermal repair after inflammation. Neuropsin and its human homologue kallikrein-related peptidase 8 (KLK8) have been reported to be involved in epidermal proliferation and differentiation, but the involved molecular mechanisms are obscure. OBJECTIVES: To explore the molecular mechanism of KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin. METHODS: The molecular mechanism involved in KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin was investigated both in vivo and in vitro using neuropsin knockout mice and KLK8 knockdown human keratinocytes. Neuropsin-related genes were identified by differential gene display. The localization and functional relationship of the molecules affected downstream of KLK8/neuropsin in normal and inflamed skin were analysed by in situ hybridization and immunohistochemistry. RESULTS: Hyperkeratosis and acanthosis in sodium lauryl sulphate-stimulated skin were markedly inhibited in neuropsin knockout mice. Knockdown of KLK8/neuropsin increased transcription factor activator protein-2α (AP-2α) expression and decreased keratin 10 expression in human keratinocytes and mouse skin, respectively. AP-2α has been reported to inhibit epidermal proliferation and keratin 10 expression. Distributional analysis showed that KLK8/neuropsin was expressed in the stratum spinosum, AP-2α was expressed in the stratum basale and the lower part of the stratum spinosum, and keratin 10 was expressed throughout the stratum spinosum. CONCLUSIONS: The above findings suggest the following mechanism of events underlying KLK8/neuropsin-induced hyperkeratosis: (i) skin inflammation increases KLK8/neuropsin expression in the stratum spinosum; (ii) the released KLK8/neuropsin inhibits AP-2α expression in the cells of the stratum basale and stratum spinosum; (iii) the decrease in AP-2α results in cell proliferation in the stratum basale and cell differentiation in the stratum spinosum, with an increase in keratin 10 expression.

Gene targeting at the mouse cytokeratin 10 locus: severe skin fragility and changes of cytokeratin expression in the epidermis.

Bullous congenital ichthyosiform erythroderma (BCIE) is a dominantly inherited blistering skin disorder caused by point mutations in the suprabasal cytokeratins 1 or 10. Targeting the murine cytokeratin 10 gene in ES cells resulted in mice with different phenotypes in the homozygotes and heterozygotes; both of which exhibit similarities to specific clinical characteristics of BCIE. Homozygotes suffered from severe skin fragility and died shortly after birth. Heterozygotes were apparently unaffected at birth, but developed hyperkeratosis with age. In both genotypes, aggregation of cytokeratin intermediate filaments, changes in cytokeratin expression, and alterations in the program of epidermal differentiation were observed. In addition we demonstrate, for the first time, the existence of the murine equivalent of human cytokeratin 16.

A mouse keratin 1 mutation causes dark skin and epidermolytic hyperkeratosis.

Chemical mutagenesis in the mouse has increased the utility of phenotype-driven genetics as a means for studying different organ systems, developmental pathways, and pathologic processes. From a large-scale screen for dominant phenotypes in mice, a novel class of pigmentation mutants was identified by dark skin (Dsk). We describe a Dsk mutant, Dsk12, which models the human disease, epidermolytic hyperkeratosis (EHK). At 2 days of age, mutant animals exhibit intraepidermal blisters and erosions at sites of trauma, and by 2 weeks of age develop significant hyperkeratosis. We identified a missense mutation in mutant animals that predicts an S194P amino acid substitution in the 1A domain of Keratin 1, a known target for human mutations that cause EHK. Dsk12 recapitulates the gross pathologic, histologic, and genetic aspects of the human disorder, EHK.

[Nail abnormalities revealing AL systemic amyloidosis]. / Anomalies unguéales révélant une amylose systémique AL.

INTRODUCTION: Mucocutaneous involvement in systemic amyloidosis occurs in 29 to 40%. Purpura and macroglossia are the most frequently signs. Nail involvement is rarely observed. We reported a case of systemic amyloidosis AL revealed by nail abnormalities. CASE REPORT: A 76-year-old-man consulted for nail lesions lasting for several months with subungual hyperkeratosis, distal onycholysis and subungual splinter hemorrhages. The remainder of the dermatological examination highlighted a faint purpuric erythema of eyelid that was overlooked. Further diagnostic work-up confirmed the diagnosis of systemic amyloidosis associated with multiple myeloma lambda light chains. CONCLUSION: Nail abnormalities in systemic amyloidosis AL are rarely described. They can take many forms and can sometimes be the only cutaneous manifestation of systemic amyloidosis. Skin biopsy of the nail matrix can confirm the diagnosis with a potential risk of sequela onychodystrophy nail. Labial salivary gland biopsy seems to be the most sensitive method for diagnosing systemic amyloidosis.

Abnormal keratin 1 and 10 cytoskeleton in cultured keratinocytes from epidermolytic hyperkeratosis caused by keratin 10 mutations.

Epidermolytic hyperkeratosis is caused by mutations of the differentiation-specific keratins K1 and K10. These mutations produce a weakened cytoskeleton that is prone to collapse resulting in cell fragility and lysis. In this study we have analyzed cultured keratinocytes from EHK patients bearing 10R-to-H and 15L-to-S mutations within the 1A segment of the K10 rod domain. Keratinocytes were grown submerged in serum-free medium and induced to differentiate by growing to confluence and increasing the Ca++ concentration in the medium. Cultures were either harvested for mRNA sequence analysis or subjected to immunofluorescence microscopy. Differentiating keratinocytes from these patients were found to express these K10 mutations in their mRNA. Moreover, these cells could be distinguished from normal keratinocytes by their aberrant morphology. EHK keratinocytes frequently exhibited a collapsed perinuclear network of K1/K10 filaments and sometimes peripheral granules of K1 and K10 aggregates, reminiscent of the cells of the suprabasal layers in these patients. This report documents the expression of mutant keratin 10 in cultured EHK keratinocytes.

Topical application of viral vectors for epidermal gene transfer.

Efficient gene transfer with extended gene expression is essential for successful treatment of skin diseases using gene therapy. Previously we evaluated a physical gene transfer method (gene gun delivery) for its ability to transfect the epidermis in vivo. In this study, we tested two viral vectors for their ability to transduce murine epidermis through topical application. Both an adenoviral vector and a herpes simplex virus (HSV) amplicon vector transduced murine epidermis with high efficiency after topical application. Differences in amount and duration of transgene expression were compared between these two vectors. Quantitative analysis of reporter lacZ gene expression showed that the viral vector-mediated gene transfers were superior to gene-gun delivery of plasmid DNA. Significant necrosis and cytotoxicity, however, were observed in the HSV-treated skin. In addition, we show that murine epidermis developed hyperkeratosis and acanthosis 4 d after an adenoviral vector containing a human TGF-alpha expression unit was applied topically. Finally we demonstrate the feasibility of transduction of fetal skin in utero by intraamniotic injection of an adenovirus vector.

[Congenital ichthyosiform erythrodermas: aspects of their etiology and pathogenesis]. / Vrozhdennye ikhtioziformnye éritrodermii: nekotorye aspekty étiologii i patogeneza.

The term "inherited ichthyosiform erythrodermia" (IIE) designates a heterogeneous group of inherited disturbances of keratinization. Lamellar ichthyosis (LI), inherited nonbullous ichthyosiform erythrodermia, bullous inherited ichthyosiform erythrodermia (BIIE) and some other conditions. Processes of terminal cell differentiation and epidermal keratinization are affected in all the above conditions. A decrease of transglutaminase activity is observed in L1, this being connected with mutations in chromosomes 14q, 2g33-35. In BIIE which is characterized by dense groups of tonofilaments in the suprabasal layer, mutations of keratin I and X coded by chromosomes 2 and 17 are identified. When sporadic forms of the disease occur, the main question is establishment of the genotype-phenotype correlation which depends on detailed characteristics of each patient and accurate study of the ultrastructural disturbances.

Persistent actinic epidermolytic hyperkeratosis.

BACKGROUND: Epidermolytic hyperkeratosis is a distinctive histologic change noted in a variety of acquired and congenital dermatoses. Its pathogenesis is unknown. We have observed acquired epidermolytic hyperkeratosis in four Japanese men. OBJECTIVE: Our purpose was to report four cases of acquired epidermolytic hyperkeratosis induced by sun exposure. METHODS: Four cases were studied clinically, histopathologically, electron microscopically, and by tissue culture. RESULTS: Flat, keratotic, slightly elevated, depigmented papules were located on the upper back, shoulders, and anterior aspect of the thighs. They appeared after excessive sun exposure. Depigmented macules coexisted with the pigmented macules. Histologic and ultrastructural examination revealed epidermolytic hyperkeratosis. Thick bundles of tonofilaments, which were also present in the cutaneous lesions, were seen in newly proliferated keratinocytes in cultures taken from depigmented papules. CONCLUSION: These results suggest that acquired epidermolytic hyperkeratosis may be induced by excessive sun exposure. We propose the term persistent actinic epidermolytic hyperkeratosis for these lesions.

Keratin and keratinization.

A flood of new knowledge and discoveries in the basic science of keratins and keratinization has appeared in the past several years. This review summarizes this recent information with a focus on the epithelial keratin polypeptides, keratin intermediate filaments, keratohyaline granule proteins, cell envelope formation and cell envelope proteins, "soft" keratinization, true disorders of keratinization (i.e., epidermolysis bullosa simplex and epidermolytic hyperkeratosis), and disease and drug effects on keratinization.