Heterogeneous keratohyalin formation in warts

Loricrin immunoreactivity in human skin: localization to specific granules (L-granules) in acrosyringia

Loricrin is a major component of the cornified cell envelope and is also expressed in the granular layer of human epidermis. In newborn mouse epidermis, loricrin accumulates in small round granules (L-granules) in the granular layer before being incorporated into the cornified cell envelope, but the expression of L-granules has not yet been demonstrated in human skin. In the present study we used postembedding immunoelectron microscopy to examine loricrin expression in normal human skin. We observed diffuse loricrin staining in the uppermost granular cell layer in interappendageal epidermis, that was not associated with any granular structures. In the cornified cells, most of the labelling was on the inner face of cornified cell envelopes. By contrast, in the upper segment of acrosyringia there were small granules (L-granules) that specifically labelled for loricrin. In the outer ductal cells, L-granules with a highly osmiophilic electron density were apparent in the nucleus as well as in the cytoplasm. In the inner ductal cells, L-granules were round or oval, less electron-dense and larger than the outer ductal L-granules, and present only in the cytoplasm. Some of the outer ductal L-granules and most of the inner ductal L-granules formed composite granules with filaggrin immunoreactive granules. These results suggest that in human interappendageal epidermis, loricrin might be rapidly incorporated into the cornified cell envelope without prior accumulation in any type of granule. By contrast, in acrosyringia loricrin accumulates in granules, perhaps reflecting increased synthesis or slower processing. The significance of the different morphological features of the L-granules in inner and outer acrosyringial cells remains to be clarified.

Medusa head-like granules in squamous cell carcinoma with differentiation toward a hair follicle structure

A case of squamous cell carcinoma (SCC) with regional lymph node metastasis in a 69-year-old Japanese man is reported. The tumor was characterized by the proliferation of peripheral basaloid, inner squamoid, and glycogen-rich cells, the presence of trichilemmal keratinization, and the presence of ladder-like, membrane-coating granules. These findings suggested that this tumor differentiates toward a hair-follicle structure. The most interesting feature of this tumor was the presence of medusa head-like granules in the cytoplasm of the clear squamoid cells adjacent to the keratinized cells. We have been unable to find any other studies of these granules in squamous cell carcinoma.

Hereditary palmoplantar keratosis of the Gamborg Nielsen type. Clinical and ultrastructural characteristics of a new type of autosomal recessive palmoplantar keratosis

A new kind of diffuse palmoplantar keratoderma with autosomal recessive inheritance and without associated symptoms was described in Norrbotten, Sweden by Gamborg Nielsen in 1985. Clinically, it ranges between the less severe dominant Unna-Thost type and the more severe recessive Meleda type, as it is milder than the latter. Skin biopsies of five patients from three different families with this new palmoplantar keratoderma, as well as five obligatory heterozygotes from one family, were investigated ultrastructurally in order to characterize this new entity and to differentiate it from the Meleda type. Several features are common to both autosomal recessive palmoplantar keratoses. They show a broadened granular layer, a transit region consisting of cells with a marginal envelope, and considerable hyperkeratosis. Morphologically, this transformation delay is less pronounced in the Gamborg Nielsen type than in the classical Meleda type. As is typical for ridged skin, both types of palmoplantar keratoses possess composite keratohyaline granules. In contrast to the normal appearance of keratohyaline granules in the Meleda type, the Gamborg Nielsen type also shows qualitative deviations of keratohyaline granules with different degrees of spongiosity and electron density and sometimes with a granular border. It seems that abnormal keratohyaline proteins are synthesized that behave differently. The sudden transformation of a granular into a horny cell is physiologically regulated by different enzymes. A delay in this process may be caused by a mutation that reduces or alters the enzymes concerned. We assume the palmoplantar keratoderma of the Gamborg Nielsen type to be a variant of the heterogeneous group of the Meleda type of palmoplantar keratoderma with autosomal recessive inheritance.

Bicomponent keratohyalin in normal human ridged skin

Up to now, bicomponent keratohyalin has only been described for rat epithelium and human intraepidermal sweat ducts and fetal nail organ cells. In normal human interductal epidermis, the keratohyalin appears homogeneous, osmiophilic and stellate in shape. Under pathological conditions, bicomponent keratohyalin has been observed in different palmoplantar keratoses and has therefore been thought to be associated with abnormal keratosis. We studied the keratinization process in normal human plantar epidermis, in which keratohyalin was found to exhibit several morphological differences as compared to that seen in non-ridged skin. The most striking feature was seen in upper granular cells, where the keratohyalin granules consisted of two components of differing electron density. The electron-dense component formed the main part of the composite granule and was found in the cytoplasm of lower and upper granular cells. The less-electron-dense component was attached to the main component and appeared in the cytoplasm of upper granular cells, forming the convex contact zone. No intranuclear osmiophilic inclusions were present. The respective electron densities of the two keratohyalin components of ridged skin were obviously different to that of the bicomponent keratohyalin granules seen in the epidermal sweat-duct cells of the same specimen. These findings indicate the presence of at least two different types of keratohyalin proteins in normal human ridged skin. They can be distinguished at the electron-microscope level and differ from the keratohyalin of human non-ridged skin as well as from bicomponent keratohyalin granules derived from human epidermal sweat-duct cells or from rat epithelium.

Filaggrin expression in cutaneous and mucosal human papillomavirus induced lesions

A series of 32 human papillomavirus induced lesions derived from epidermis and mucosa was studied for the modulation of filaggrin-profilaggrin (F-PF) expression according to the degree of virus infection as compared to normal skin and mucosa biopsies. This investigation was carried out on frozen sections using indirect immunofluorescence for filaggrin detection and group specific viral antigen and by in situ hybridization with biotinylated probes for viral DNA detection and typing. The 9 cutaneous warts showed an increase of F-PF expression in upper layer cells as compared to normal epidermis, which could be related to the high production of virus (viral antigen and HPV types 1 or 2). The 5 condyloma acuminata displayed also an enhanced expression of these components which was located in several upper layers but virus infection was confirmed in 2 of them with HPV types 6, 11 or 16. The 6 laryngeal papillomas exhibited a granular reactivity pattern for F-PF in suprabasal cell layers with an increase in the upper layers; viral antigen was found in 4 cases and HPV DNA types 6, 11 or 16 were detected in 4 specimens. Conversely among 12 cervical intraepithelial neoplasia, F-PF was expressed only in very superficial layers in few cases, without any correlation with the DNA detection (6, 11 or 16, 18). Taken together these data are suggestive of an intense expression of F-PF in benign lesions which can replicate the virus and a discrete or an absent expression of these components in premalignant or malignant lesions.

The morphology of keratohyalin granules in orthokeratotic and parakeratotic skin and oral mucosa

We compared morphologic features of keratohyalin granules (KHG) that were directly related to keratinization in oral mucosa (tongue, cheek, gums, palate; n = 4) with those in parakeratotic epidermis (psoriasis, n = 2; pityriasis rubra pilaris, n = 1; acute dermatitis, n = 1) and normal orthokeratotic epidermis. Among others, the ultrastructural features of globular KHG were observed in the cheek, nonspecialized tongue mucosa, and parakeratotic epidermis occurring in psoriasis, pityriasis rubra pilaris, and acute dermatitis, whereas gums and palate showed a mixture of characteristics, also resembling stellate KHG as seen in normal skin. From literature as well as from our studies, the impression was gained that globular KHG were found especially in quickly dividing epithelia and could easily be distinguished from the irregular or stellate KHG that were found in slowly dividing normal epidermis. Therefore, we studied keratinization features on days 3, 7, and 14 after autografting normal human skin (n = 4), thus inducing high cell turnover. Stellate KHG, present in granular cells of normal skin, were almost absent on the third day. Active cell division on the seventh day resulted in sparse keratohyalin formation inside globular granules of low electron density, whereas numerous, rather electron-translucent lipid droplets occurred in upper spinous and horny cells. These two phenomena seemed to be interrelated. After 14 days, round and increasingly electron-dense KHG were noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Composite keratohyaline granules in palmoplantar keratoderma: an ultrastructural study

We report the results of an ultrastructural study of the hyperkeratotic epidermis in 23 cases of palmoplantar keratoderma (PPK) comprising 8 inherited keratoderma, 8 keratoderma climactericum in menopausal women and 7 symptomatic keratoderma. In all but one of the cases of inherited PPK and keratoderma climactericum, composite keratohyalin (KH) granules were found in granular cells of the interductal epidermis, which were similar to those found in the rat and in some other conditions. In the cases of symptomatic keratoderma, e.g. secondary to eczema, the appearance of the KH granules did not differ from that of granules observed in two normal plantar skin samples. While the real role played by these granules is unknown, they could constitute a differentiation marker of intraepidermal duct cells, and their abundance in PPK suggest that intraepidermal sweat ducts may play a part in PPK histogenesis.

Electron microscopy of composite and intranuclear keratohyalin granules in geographic tongue of psoriasis

Composite and intranuclear keratohyalin granules were observed in an electron-microscopic study of geographic tongue of psoriasis. The significance of intranuclear keratohyalin is not known, but it seems to be related to the disturbed proliferation and differentiation of keratinocytes in psoriasis.

Two anatomoclinical types of warts with plantar localization: specific cytopathogenic effects of papillomavirus. Type I (HPV-1) and type 2 (HPV-2)

In this study, the clinical and histopathological aspects of 50 plantar warts are reported in relation to the type of papillomavirus present in the lesions, as detected by immunofluorescence tests, using specific guinea pig fluorescein-labelled IgG. Warts of plantar localization are not caused by the same human papillomavirus (HPV) since they are found to be associated with both HPV type 1 (HPV-1) and HPV type 2 (HPV-2). HPV-1 is always associated with deep and painful plantar warts (myrmecia), whereas HPV-2 is found to be associated with superficial, painless plantar warts (vulgaris or often mosaic type). Histologically, these two types of plantar warts are quite different. In myrmecia (HPV-1), characterized by an endophytic growth, large eosinophilic, keratohyaline-like granules are observed in the cytoplasm and nucleus of infected, often vacuolated cells. These granules appear early in stratum spinosum and are very numerous in stratum granulosum. In the mosaic type (HPV-2), the histopathological aspect is not different from that of common warts; these lesions have an exophytic growth and are characterized by foci of clear vacuolized cells which are found in stratum granulosum. Their cytoplasm contains round, basophilic keratohyalin granules which often have a heterogenous aspect. These differences are observed in other localizations of morphologically related warts associated with HPV-1 and HPV-2 and seem to be related to a specific cytopathogenic effect of HPV-1 an HPV-2 in human papillomas.

[Histologic and electron microscopical investigations in a patient with benign verrucosis generalisata (author's transl)]

A report is given on a 43-year-old man who has been suffering from pointed condylomata in the region of scrotum and anus since 1975. Repeated relapses. Since 1977 verrucous lesions spreading from thorax to both arms and the throat. Histologic examination revealed intraepidermal foci of balloon cells in the stratum spinosum and stratum granulosum, partly with intranuclear basophilic inclusions. Electron microscopy showed an intact basal lamina and also partly intact epidermis. Only in the focal area the epidermopoiesis is disturbed already from the basal layer, with vacuolated destruction of the basal keratinocytes and condensation of the cytoplasm, as well as formation of myelin figures. This degenerative process together with enlarged intercellular spaces and partly conserved desmosomes continues into the stratum granulosum. From the upper stratum spinosum balloon cells characteristic for warts are found. In the stratum granulosum there are abundant atypic keratohyalin granules, and in the stratum granulosum and stratum corneum characteristic virus-containing kerationcytes are found. Furthermore, there are lots of released virus elementary bodies deposited in bizarre shapes at the horny lamellae: crystalloid or garland-, chain-, letter-, or wreath-shaped.