Cases reported "Skin Diseases"

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1/6. skin fragility and hypohidrotic ectodermal dysplasia resulting from ablation of plakophilin 1.

    We report a 2-year-old boy with an unusual autosomal recessively inherited skin disease comprising trauma-induced skin fragility and congenital ectodermal dysplasia affecting hair, nails and sweat glands. skin biopsy showed widening of intercellular spaces between keratinocytes and ultrastructural findings of small, poorly formed desmosomes with reduced connections to the keratin filament cytoskeleton. Immunohistochemical analysis revealed a complete absence of staining for the accessory desmosomal plaque protein plakophilin 1 (PKP1; band 6 protein). The affected individual was a compound heterozygote for null mutations on both alleles of the PKP1 gene. Both mutations occurred within the amino terminus of PKP1, the domain which normally binds the cytoskeletal keratin filament network to the cell membrane. Apart from its localization within desmosomal plaques, PKP1 may also be present within the cytoplasm and nucleus and has putative roles in signal transduction and regulation of gene activity. The clinicopathological observations in this patient demonstrate the relevance of PKP1 to desmosome formation, cutaneous cell-cell adhesion and epidermal development and demonstrate the specific manifestations of human functional knockout mutations in this gene.
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ranking = 1
keywords = desmosomes
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2/6. A novel genodermatosis caused by mutations in plakophilin 1, a structural component of desmosomes.

    desmosomes are adhesive intercellular junctions that link adjacent cells and provide anchoring points for the keratin filament cytoskeleton. The mechanical integrity of desmosomes depends on a complex network of transmembranous and cytoplasmic proteins and glycoproteins each encoded by distinct genes. Recently, naturally occurring human mutations in one of these desmosomal structural components, plakophilin 1, have been described. The clinical features of the affected individuals, who have total ablation of plakophilin 1, comprise a combination of skin fragility and ectodermal dysplasia with loss of hair, reduced sweating and nail dystrophy. desmosomes in the skin are small and poorly formed and there is widening of intercellular spaces between keratinocytes as well as detachment of the keratin filament network from the cell membrane. These clinicopathological observations demonstrate the relevance of plakophilin 1 to keratinocyte adhesion and epidermal morphogenesis. This new form of genodermatosis represents the first example of human desmosome gene mutations and its clinical and ultrastructural characteristics are highlighted in this article.
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ranking = 5
keywords = desmosomes
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3/6. Hereditary mucoepithelial dysplasia. Case report and review of the literature.

    Hereditary mucoepithelial dysplasia, a dyshesive, dyskeratotic epithelial syndrome caused by an abnormality in desmosomes and gap junctions, involves the mucosae, skin, hair, eyes, and lungs. A 16-year-old patient had nontender, fire-red mucosae; keratosis pilaris; diffuse, nonscarring alopecia; cataracts; photophobia; corneal vascularization; and decreased visual acuity. Histologic examination of gingival sections showed a dyshesive epithelium with atrophy, dyskeratosis, lack of keratinization, and unusual cytoplasmic inclusions. Results of electron microscopic studies showed a reduced number of desmosomes, amorphous intercellular material, and cytoplasmic inclusions resembling tonofilaments and gap junction material. The patient described in this report represents an apparently sporadic case of hereditary mucoepithelial dysplasia. Other cases described previously in the literature are reviewed. We believe this disorder should be brought to the attention of dermatologists because patients with hereditary mucoepithelial dysplasia have numerous skin problems and are susceptible to recurrent infection and potentially fatal bullous lung disease. Also, misinterpreted abnormal results from cervical Pap smears could lead to hysterectomy being performed unnecessarily on these patients.
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ranking = 2
keywords = desmosomes
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4/6. Trichilemmal keratosis (horn): a light and electron microscopic study.

    Three cases of trichilemmal keratosis (horn) were light microscopically examined and all showed numbers of U- or V-shaped epidermal proliferations which keratinized in a fashion either identical or similar to trichilemmal keratinization. Electron microscopy revealed both uneven and linear borders between the keratinized and the keratinizing cells with a few keratohyalin droplets, remnants of desmosomes, no marginal band in the horny layer, perinuclear vacuolation, few spherical bodies in the intercellular spaces (ICS) of the upper epidermis, and widening of the ICS of the lower epidermis. A number of electron dense spherical particles, 40-50 nm in diameter, were observed in nuclei of the upper epidermis. This suggests that ultrastructure of trichilemmal keratosis is similar rather to viral warts than to trichilemmal cysts, although there are close similarities between trichilemmal keratosis and cyst.
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ranking = 1
keywords = desmosomes
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5/6. Proliferating trichilemmal cyst: an ultrastructural study.

    A 73-year-old woman had a walnut-sized tumor in the occipital region for 10 years. The growth consisted of multiple small and large cystic epithelial masses. The cyst wall exhibited trichilemmal keratinization. Numerous squamous eddies as well as many glycogen-rich cells were present in the cyst wall. Some small round keratohyalin granules were observed in the cells below the horny layer. The desmosomes and masses of lipid droplets were seen in the horny layer. The findings described above are similar to those observed in the follicular isthmus and the follicular infundibulum. Other interesting findings include the presence of intranuclear inclusions of tonofilament-like material and/or keratohyalin-like granules within the cells near the mid-layer of the cyst wall.
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ranking = 1
keywords = desmosomes
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6/6. Mucinous syringometaplasia. An immunohistochemical and ultrastructural study of a case.

    Mucinous syringometaplasia (MS) is an unusual skin lesion of unknown etiology, characterized histologically by epidermal invaginations lined by mucin-laden goblet-like cells and by nonkeratinized squamous cells. The present case study was performed to elucidate further the characteristics of this lesion using immunohistochemistry and electron microscopy. The mucin-laden cells in the MS lesion stained positively for carcinoembryonic antigen, epithelial membrane antigen, and low molecular weight keratins. The ultrastructural examination, which was performed on deparaffined sections, revealed two morphological variants of mucous granules. Electron-dense mucous granules predominated in the mucus-containing cells, which were situated among the keratinocytes adjacent to the epidermal invaginations, mostly in the lower parts of the epidermis. Larger, electron-lucent granules containing flocculent material were found more abundantly in the cells lining the epidermal invaginations. Also, some of the mucus-containing cells showed bundles of tonofilaments; structures that appeared to be isolated short, stubby microvilli; and attachments to adjacent mucus-containing cells and keratinocytes by desmosomes. The ultrastructural and immunohistochemical findings in our case suggest that the mucinous changes occurred as a metaplastic process in the resident epidermal cells and were accompanied by changes in cellular antigen expression resembling those of simple secretory epithelium.
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ranking = 1
keywords = desmosomes
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