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Notes: We report a case of follicular keratosis with inflammatory changes, consistent with a diagnosis of atypical juvenile pityriasis rubra pilaris. An unusual feature was the occurrence of severe Staphylococcus aureus folliculitis and furunculosis, a phenomenon rarely encountered in pityriasis rubra pilaris and the other follicular keratoses. Standard antibiotic and antiseptic treatment for chronic S. aureus infection was ineffective. The patient was subsequently found to have hypogammaglobulinaemia, and treatment with human polyvalent immunoglobulin infusions was successful in eradicating the sepsis. It is therefore probable that the hypogammaglobulinaemia played a pathogenic role in the development of cutaneous sepsis.

Notes: Summary The aim of this study was to characterize cell-cell and cell-matrix interaction by evaluating the expression of different integrins in the nail matrix.Nail biopsies were obtained from two cadaver lingers, and eight patients with ingrowing toenails. Frozen sections were stained by indirect immunofluorescence using anti-α, anti-α2, anti-α3 anti-α4, anti-α5, anti-α6, anti-αv, anti-β. anti-β4 and anti-ICAM-1 monoclonal antibodies. Biopsies from normal human foreskin were evaluated as controls, α. α4 and α5 subunits were absent from both nail matrix and normal human skin. α2, α3 and β1 subunits were expressed in the basal and suprabasal layers of nail matrix, but only in the basal layer of skin epidermis, α6 and β4 subunits were strongly expressed in the basement membrane zone and in the basal layer of both nail matrix and epidermis. The αv subunit was expressed in the basal layer of nail matrix. ICAM-1 was not expressed in nail matrix epidermis.Our findings show that despite the distinctive features of the nail apparatus, compared with the epidermis, the pattern of integrin expression Is similar, although some differences in the distribution of α2. α3 and β1 subunits are detectable. These are probably related to the peculiar differentiation and keratinization of the nail.

Notes: Summary We report two cases of acquired fibrokeratoma which present new clinical and histological features specific to the nail apparatus. There are three histological characteristics, (i) A deep epithelial invagination which develops from the proximal nail fold and is orientated in the same direction as, but is more proximal than, the normal matrix, (ii) The postero-inferior aspect of the cul-de-sac produced by the invagination acts as an accessory matrix, giving rise to a pseudo-nail plate. The granular layer is reduced or absent, (iii) This accessory nail apparatus lies on a conical dermal tumour, sharply demarcated from the surrounding dermis, with a wide base narrowing towards the tip. The finger shaped structure is reminiscent of Kint's type I acquired fibrokeratoma.

Notes: Background  Superficial white onychomycosis (SWO) is a distinct pattern of fungal nail invasion, which is usually treated with topical antifungals.Objective  This paper presents a case of SWO with deep penetration and records other similar cases.Methods  The clues to deep invasion of the nail plate are twofold: an inability to clear the discoloration by scraping the nail and a clinical involvement of the nail plate in the proximal nailfold area. Histology of the nail keratin will confirm deep penetration beyond the superficial layers of the nail plate.Results  In the light of this finding the authors propose a further subdivision of SWO to reflect previously unrecognized variants with therapeutic implications into: (i) the classical SWO type; (ii) the dual invasion of the nail plate, superficial and ventral; and (iii) the pseudo-SWO with deep fungal invasion of the nail plate.Conclusions  This subdivision of SWO allows the clinician to treat the patient appropriately using topical antifungals when the disease is restricted to the dorsum of the nail. Systemic drugs either in isolation or in combination with topical treatment are mandatory when deep penetration or ventral fungal invasion are observed.

Notes: 11β-Hydroxysteroid dehydrogenase (11β-OHSD) metabolizes corticosterone to inactive 11-dehydrocorticosterone and thus protects non-specific mineralocorticoid receptors from exposure to corticosterone in the kidney in vivo. Clearly, 11β-OHSD might also regulate corticosterone access to glucocorticoid receptors. We have investigated cerebellum, a tissue with high glucocorticoid receptor, but very low mineralocorticoid receptor levels and have shown marked 11β-OHSD bioactivity with similar co-substrate requirements and inhibition kinetics to the renal enzyme. 11β-OHSD messenger ribonucleic acid was expressed in cerebellum and was localized in Purkinje and granule cells. This distribution was confirmed immunohistochemically. Thus, we provide evidence for 11β-OHSD in cerebellum and suggest that it may regulate the access of corticosterone to glucocorticoid receptors in addition to mineralocorticoid receptors.

Notes: Two patients with AIDS are described who developed acral hyperpigmented macules of the fingers, palms and soles, buccal mucosa and genitalia, associated with longitudinal melanonychia. These pigmentary changes seemed to be independent of zidovudine and were associated in one with diffuse melanoderma and elevated levels of α-MSH. Histological and ultrastructural studies showed an increase of the dendrites and pigmentation of the melanocytes and few melanosomes in the keratinocytes.

Notes: Summary A case of fixed-drug eruption due to cefalexine presented with acute paronychia. Twenty days after a further challenge with a single dose of the drug, a biopsy of the affected skin showed intense expression for ICAM-1.

Notes: Background  Recently, the expression profiles of the members of the complex hair keratin family have been determined in the human anagen hair follicle. In contrast, the details of hair keratin expression in the human nail unit are poorly known.Objectives  In order to fill this gap, we have performed an immunohistochemical study of the adult human nail unit by means of specific antibodies against nine hair keratins of both types (hHa2, hHb2, hHa5, hHb5, hHa1, hHb1, hHb6, hHa4 and hHa8) as well as three epithelial keratins (K5, K17 and K10).Methods  Formalin-fixed paraffin sections of adult nails were examined using monoclonal and polyclonal keratin antibodies, respectively. Longitudinal as well as transverse sections were investigated.Results  Our study revealed two types of epithelial tissue compartments in the nail unit. The first comprised the eponychium and hyponychium and the nail bed, which expressed only epithelial keratins. While keratins K5, K17 (basal) and K10 (suprabasal) were found in the orthokeratinizing eponychium and hyponychium, throughout, the nail bed epithelium expressed only K5 and K17. The second type comprised the apical and ventral matrix which exhibited a mixed pattern of epithelial and hair keratin expression. Thus, K5 and K17 were expressed in the entire multilayered basal cell compartment of the apical and ventral matrix; however, in the latter, K5 and K17 also occurred in the lowermost layers of the overlying keratogenous zone. The hair matrix keratin hHb5, but not its type II partner hHa5, was seen in the entire keratogenous zone of the apical and ventral matrix, but was also located in the uppermost cell layers of the basal compartment of the ventral matrix, where it overlapped with K5 and K17. Similar to their sequential expression in the hair follicle cortex, hair keratins hHa1, hHb1, hHb6 and hHa4 were consecutively expressed in the keratogenous zone of both the ventral and, albeit less distinctly, apical matrix, with hHa1 initiating in the lowermost cell layers. The expression of hHa8 in only single cortex cells of the hair follicle was also preserved in cells of the keratogenous zone. In the region of the so-called dorsal matrix, we observed two histologically and histochemically distinct types of epithelia: (i) a dominant type, histologically similar to the eponychium and an associated K5, K17 and K10 keratin pattern which clearly extended into the apical matrix, and (ii) a minor type, histologically resembling the postulated dorsal matrix without a granular layer and a cuticle, and exhibiting extended K5 expression as well as hair keratin expression in superficial cells.Conclusions  The coexpression of hHb5 with K5 and K17 in the uppermost cell layers of the basal compartment and the lowermost layers of the keratogenous zone of the ventral matrix prompts us to designate this region the prekeratogenous zone of the ventral matrix. The two alternating types of histology and keratin expression in the dorsal matrix identify this region as a transitional zone between the eponychium and the apical matrix. Finally, our data clearly show that the ventral matrix is the main source of the nail plate. In addition, the mixed scenario of hair and epithelial keratins, including demonstrable amounts of K10, in superficial cells of the apical matrix, lends support to the notion that the dorsal portion of the nail is generated by the apical matrix.

Notes: We report the first case of subungual perineurioma presenting as clubbing of one finger, an unusual clinical feature. Histological study showed a myxoid tumour but with, unexpectedly, a diffuse expression of CD34. Differential diagnoses between perineurioma and myxoid soft tissue tumours expressing CD34 are discussed.