Sebaceous Duct Research Articles

Defensins and acne

Acne a disease of the pilosebaceous unit is characterised by hypercornification and hyperkeratosis of outer root sheath (ORS) and sebaceous duct and perilesional infiltrate. Lesions may be characterised as “non”-inflammatory versus inflammatory. Hypercornification of the distal ORS and the pilosebaceous duct in concert with increased sebum production and abnormalities of the microbial flora are considered to be major factors in the pathogenesis of acne vulgaris. However, the basic mechanisms involved in the development of inflammation during acne vulgaris remain unclear. We have investigated the expression patterns of two antimicrobial peptides, human beta-defensin 1 (hBD1) and human beta-defensin 2 (hBD2) in healthy human hair follicles as well as in peri- and intralesional skin of acne vulgaris lesions such as comedones, papules and pustules. Strong hBD1 and hBD2 immunoreactivity was found in all suprabasal layers of the epidermis, and all permanent compartments of the hair follicle including the distal ORS of the hair follicle and the pilosebaceous duct. Moreover, marked hBD1 and hBD2 expression was also detected in the hair follicle stem cell compartment. In contrast, the proximal follicle bulb which undergoes apoptotic regression and is also able to regenerate following injury did not express hBD1 or hBD2. The majority of acne biopsies displayed a marked upregulation of hBD2 IR in the lesional and perilesional epithelium; in particular in pustules, and a less marked upregulation of hBD1 IR. The upregulation of beta-defensins expression in acne vulgaris lesions when compared to controls suggests that beta-defensins may be involved in the pathogenesis of acne vulgaris.

ACNE VULGARIS. GRADES OF SEVERITY AND TREATMENT OPTIONS

Acne is the most common skin condition treated by dermatologists. Acne is a polymorphic disease exhibiting a number of diverse lesions: comedones, papules, pustules, nodules, cysts, sinuses and scars. Despite this diversity, acne can be reduced to a two-stage sequence of events. Firstly an abnormal hypercornification and desquamation in the infundibular segment of the pilosebaceous unit (the infundibulum is the part of the hair follicle from the orifice of the sebaceous gland duct to the opening on the surface) leads to the formation of a comedo, initially without an inflammatory component; and later an inflammatory reaction results in disorganisation of the epithelial capsule. SA Fam Pract 2003;45(9): 32-36

Human Skin is a Steroidogenic Tissue: Steroidogenic Enzymes and Cofactors Are Expressed in Epidermis, Normal Sebocytes, and an Immortalized Sebocyte Cell Line (SEB-1)

Although the human sebaceous gland can synthesize cholesterol from acetate and can further metabolize steroids such as dehydroepiandrosterone into potent androgens, the de novo production of steroids from cholesterol has not been demonstrated in human skin. The goal of this study was to delineate the steroidogenic pathway upstream from dehydroepiandrosterone by documenting the presence of members of the P450 side chain cleavage system (P450scc). This system catalyzes the initial step in steroid hormone synthesis following translocation of cholesterol to the inner mitochondrial membrane. In concert with its cofactors, adrenodoxin and adrenodoxin reductase, and the transcription factor steroidogenic factor 1, P450scc converts cholesterol to pregnenolone. An SV40 immortalized human sebaceous gland cell line (SEB-1) was established in order to facilitate investigation of the P450scc system. The sebaceous phenotype of SEB-1 sebocytes was confirmed using immunohistochemistry, Oil Red O staining, and gene array expression analysis. Presence of P450scc, adrenodoxin reductase, cytochrome P450 17-hydroxylase (P450c17), and steroidogenic factor 1 was documented in human facial skin, human sebocytes, and SEB-1 sebocytes. Using immunohistochemistry, antibodies to the above proteins localized to epidermis, hair follicles, sebaceous ducts, and sebaceous glands in sections of facial skin. Results of immunohistochemistry were confirmed with Western blotting. Biochemical activity of cytochrome P450scc and P450c17 was demonstrated in SEB-1 sebocytes using radioimmunoassay. The relative abundance of mRNA for P450scc, P450c17, and steroidogenic factor 1 in SEB-1 sebocytes and sebaceous glands was compared to mRNA levels in ovarian theca and granulosa cells using real-time quantitative polymerase chain reaction. Gene array expression analysis and quantitative polymerase chain reaction indicated that mRNA for P450scc is more abundant than mRNA for both P450c17 and steroidogenic factor 1 in sebaceous glands and SEB-1 cells. These data demonstrate that the skin is in fact a steroidogenic tissue. The clinical significance of this finding in mediating androgenic skin disorders such as acne, hirsutism, or androgenetic alopecia remains to be established.

Elucidating the pulsed-dye laser treatment of sebaceous hyperplasia in vivo with real-time confocal scanning laser microscopy

Background: Several case reports document successful treatment of sebaceous hyperplasia with the pulsed-dye laser. Moreover, noninvasive real-time confocal laser scanning microscopy elucidates the vascular nature of these lesions and their pathophysiologic response to treatment mediated by vessel coagulation. Methods: Ten patients with 29 lesions of sebaceous hyperplasia were treated with 3 stacked 5-mm pulses of the 585-nm pulsed-dye laser at fluences of 7 or 7.5 J/cm2. Confocal imaging was performed before and immediately after treatment, as well as at 2, 4, and 8 weeks of follow-up. Results: The great majority of lesions responded to one treatment, with complete disappearance in 28%, decrease in diameter in 66%, and flattening in 93%. Although 28% recrudesced after initial involution, only 7% recurred completely. Three lesions became eroded or crusted, and 7 experienced cutaneous depressions before complete healing, but no scarring or pigmentary side effects were noted. Confocal imaging revealed a prominent “crown” of blood vessels surrounding the sebaceous duct and coagulation of these vessels with pulsed-dye laser treatment. However, the vessels reappeared during follow-up, and no noticeable morphologic changes in the sebaceous duct were noted. Conclusion: Vascular targeting of sebaceous hyperplasia can be monitored with real-time reflectance confocal microscopy. Most sebaceous hyperplasia regresses after one treatment with 3 stacked pulses of the 585-nm pulsed-dye laser. Whether this response is due to temporary ischemia induced by selective vessel destruction or nonspecific thermal diffusion beyond the vessels from pulse stacking has not been determined. (J Am Acad Dermatol 2000;43:49-53.)

Immunohistochemical localization of types 1 and 2 5alpha-reductase in human scalp.

The predominant form of 5alpha-reductase (5aR) in human scalp is 5aR1. None the less, clinical studies have shown that finasteride, a selective inhibitor of 5aR2, decreases scalp dihydrotestosterone and promotes hair growth in men with androgenetic alopecia. Immunolocalization studies were thus carried out to examine 5aR isozyme distribution within scalp and, in particular, to determine whether 5aR2 might be associated with hair follicles. 5aR2 was localized using both a rabbit polyclonal and a mouse monoclonal antibody. 5aR1 was detected with a mouse monoclonal antibody. The specificity of these reagents was demonstrated both by immunofluorescence and Western blot analyses of COS cells overexpressing human 5aR1 or 5aR2. When cryosections of scalp from men with androgenetic alopecia were stained with antibody against 5aR2, using immunoperoxidase avidin-biotin complex methodology, immunostaining was observed in the inner layer of the outer root sheath and, in more proximal regions of the follicle, in the inner root sheath. Staining was also prominent in the infundibular region of the follicle, with less intense staining extending throughout the granular layer of the epidermis. Some staining was also seen in sebaceous ducts. Similar results were obtained with both the polyclonal and monoclonal 5aR2 antibodies. In contrast, in scalp cryosections stained with antibody to 5aR1, no immunostaining was observed within hair follicles. Intense staining for the type 1 isozyme was, however, detected within sebaceous glands. Our immunolocalization data suggest that the results seen in clinical trials of men with male pattern hair loss treated with finasteride may be due, at least in part, to local inhibition of 5aR2 within the hair follicle.

The expression of stratum corneum chymotryptic enzyme in human anagen hair follicles: further evidence for its involvement in desquamation-like processes.

At sites with a continuous formation of cornified epithelia, there is need for continuous cell shedding in order to maintain normal anatomy. Stratum corneum chymotryptic enzyme (SCCE) has been suggested to mediate this process by degrading intercellular cohesive structures in interfollicular epidermis. In the hair follicle, there are several different kinds of cornification processes. With the exception of the formation of the hair shaft, these processes lead to a continuous formation of structures that have to be shed continuously in order to avoid distorting the anatomy of the follicle. In this work, we have investigated the possible involvement of SCCE in the turnover of cornified cells in anagen hair follicles. Using immunohistochemistry, we demonstrated the expression of SCCE in all parts of the follicle where cells are keratinized and eventually shed, i.e. in the uppermost follicle (distal to the opening of the sebaceous duct), in the sebaceous duct and in all parts of the inner root sheath (IRS). SCCE expression was also seen in those cells of the outer root sheath that are believed to move along with the IRS from the bulb and eventually become keratinized and sloughed in the part of the follicle situated between the terminal edge of the IRS and the opening of the sebaceous duct. We could not detect any SCCE in cells forming the hair shaft. Thus, there was a strong correlation between SCCE expression and the continuous formation and shedding of cornified epithelia in anagen hair follicles. This correlation was stronger for SCCE than for a number of common markers of terminal differentiation in keratinocytes. Our results give further support to a part for SCCE in desquamation-like processes. Whether SCCE is involved in diseases affecting hair growth remains to be elucidated.

Expression of stratum corneum chymotryptic enzyme in human sebaceous follicles.

Stratum corneum chymotryptic enzyme (SCCE) may be involved in desquamation, a process necessary for maintaining a normal anatomy at all sites where there is continuous turnover of cornified epithelia. Using immunohistochemistry and in situ hybridization, we have, in this work, analysed SCCE expression in the sebaceous follicle. We found expression of SCCE in luminal parts of the pilary canal, common sebaceous ducts and proximal sebaceous ducts. In addition, SCCE was seen in cells apparently situated within the distal parts of the glandular lobules. Co-expression of SCCE and keratin 10 was seen only in the pilary canal and the common sebaceous ducts. The results give further support for SCCE being involved in desquamation-like processes. The association with cornification seems to be more general for SCCE than for keratin 10. The possible role of SCCE in diseases involving disturbances in the turnover of cornified cells in the sebaceous follicle, such as acne vulgaris, is a question for future studies.

New Insight into the Topical Management of Excessive Sebum Flow at the Skin Surface

The sebum flow dynamics at the skin surface results from a multistep process starting with sebocyte proliferation, intracellular lipid synthesis, cell lysis in the sebaceous duct, storage of sebum in the follicular reservoir, discharge through the follicular opening and spreading over the stratum corneum. A handful of topical products may decrease the sebum output, most of them acting at the level of the follicular reservoir function. Among them, elubiol exhibits a clinically relevant effect on oily skin.

Feline acne and results of treatment with mupirocin in an open clinical trial: 25 cases (1994–96)

Clinical and diagnostic parameters, and response to topical mupirocin in 25 cats with feline acne are described. The chin was the most common area affected, but the lower lip, upper lip and the commissure of the lips also frequently had lesions. The most common clinical sign was the presence of crusts, followed by comedones, erythema, alopecia, pruritus and nodules/fistulas. Deep skin scrapings for ectoparasites, cytological examination of superficial skin scrapings, and fungal cultures from the chin were performed on all cats. Dermatophytes were cultured from two cats and Malassezia pachydermatis was cultured (n = 2), seen on cytology smears (n = 1), or noted on histopathology (n = 1). Skin biopsies were obtained from three of the cats and most commonly showed dilatation of sebaceous gland ducts, neutrophilic or pyogranulomatous infiltration of the sebaceous glands, and pyogranulomatous inflammation of the dermis. All cats were treated with topical 2% mupirocin ointment twice daily for 3 weeks as the sole treatment. Treatment response was excellent in 15 cats and good in nine cats. One cat had a contact reaction to the mupirocin, necessitating stopping treatment. The response to treatment of the six cats with dermatophyte or years involvement was good (n = 3) or excellent (n = 3).

Activity of type 1 5α-reductase is greater in the follicular infrainfundibulum compared with the epidermis

The enzyme 5 alpha-reductase converts testosterone (T) to dihydrotestosterone (DHT). Although this enzyme has been localized to various regions of the pilosebaceous unit, its activity has not been studied in the follicular portion of either vellus or sebaceous follicles. The goal of our study was to determine the relative activities of 5 alpha-reductase within various regions of these follicles with particular emphasis on the infrainfundibulum. A finding of increased 5 alpha-reductase activity in upper follicles compared to epidermis might support the hypothesis that increased follicular production of DHT is involved in the hyperkeratinization observed in this region of the follicle in acne vulgaris. 5 alpha-reductase activity was determined at pH 5 (optimal for the type 2 isozyme) and pH 7 (optimal for the type 1 isozyme) in isolated infrainfundibular segments from sebaceous and vellus follicles, homogenized epidermis from various anatomical areas and in microdissected segments of the pilosebaceous unit from breast skin of normal subjects. Enzyme activity was also determined at pH 7 in cultured infrainfundibular keratinocytes and in interfollicular epidermal keratinocytes. Homogenates of infrainfundibular segments demonstrated significantly greater activity at pH 7 compared to pH 5 (P < 0.001), confirming activity of the type 1 5 alpha-reductase in this region. Activity of 5 alpha-reductase was much lower in homogenized epidermis and did not demonstrate a clear pH preference. Keratinocytes cultured from the infrainfundibulum demonstrated significantly greater 5 alpha-reductase activity compared to keratinocytes from interfollicular epidermis (P = 0.04). In the dissected segments of pilosebaceous units from breast skin, 5 alpha-reductase activity was greatest in the sebaceous gland followed by the sebaceous duct, infrainfundibulum, whole skin and epidermis. These data indicate that 5 alpha-reductase activity varies within regions of the pilosebaceous unit and compared with interfollicular epidermal cells, infrainfundibular keratinocytes have an increased capacity for producing androgens which may play a role in the follicular hyperkeratinization seen in acne.

Activity of type 1 5α–reductase is greater in the follicular infrainfundibulum compared with the epidermis

The enzyme 5 alpha-reductase converts testosterone (T) to dihydrotestosterone (DHT). Although this enzyme has been localized to various regions of the pilosebaceous unit, its activity has not been studied in the follicular portion of either vellus or sebaceous follicles. The goal of our study was to determine the relative activities of 5 alpha-reductase within various regions of these follicles with particular emphasis on the infrainfundibulum. A finding of increased 5 alpha-reductase activity in upper follicles compared to epidermis might support the hypothesis that increased follicular production of DHT is involved in the hyperkeratinization observed in this region of the follicle in acne vulgaris. 5 alpha-reductase activity was determined at pH 5 (optimal for the type 2 isozyme) and pH 7 (optimal for the type 1 isozyme) in isolated infrainfundibular segments from sebaceous and vellus follicles, homogenized epidermis from various anatomical areas and in microdissected segments of the pilosebaceous unit from breast skin of normal subjects. Enzyme activity was also determined at pH 7 in cultured infrainfundibular keratinocytes and in interfollicular epidermal keratinocytes. Homogenates of infrainfundibular segments demonstrated significantly greater activity at pH 7 compared to pH 5 (P < 0.001), confirming activity of the type 1 5 alpha-reductase in this region. Activity of 5 alpha-reductase was much lower in homogenized epidermis and did not demonstrate a clear pH preference. Keratinocytes cultured from the infrainfundibulum demonstrated significantly greater 5 alpha-reductase activity compared to keratinocytes from interfollicular epidermis (P = 0.04). In the dissected segments of pilosebaceous units from breast skin, 5 alpha-reductase activity was greatest in the sebaceous gland followed by the sebaceous duct, infrainfundibulum, whole skin and epidermis. These data indicate that 5 alpha-reductase activity varies within regions of the pilosebaceous unit and compared with interfollicular epidermal cells, infrainfundibular keratinocytes have an increased capacity for producing androgens which may play a role in the follicular hyperkeratinization seen in acne.

Effects of topical antiandrogen and 5-alpha-reductase inhibitors on sebaceous glands in male fuzzy rats.

The fuzzy rat, a genetic mutant between hairless and hairy albino rats, expresses androgen-dependent hypersecretion of sebum and hyperplastic sebaceous glands. Using this model for human acne, we examined the effects of inhibitors of human steroid 5 alpha-reductase isozymes, type I (MK 386) and type II (finasteride), and an androgen receptor blocker (RU58841) on regression of glandular and ductal hyperplasia. The above three agents, 1% weight volume, were dissolved into the vehicle (propylene glycol, alcohol and water) and applied on the backs of peripubertal male rats for 2 months. Control and castrate groups received vehicle alone. At 8 weeks, we examined the size the sebaceous glandular lobules and ducts in split epidermal preparations as well as in frozen sections of skin stained with osmium-potassium dichromate solution. The number of bromodeoxyuridine (BrdU)-positive cells was counted in the glandular lobes in split-skin tissues stained with BrdU immunochemistry. The results revealed that the sizes of both lobes and ducts in castrates were 40-60% smaller than in controls. RU58841 induced glandular and ductal regression equivalent to that in castrates. Finasteride induced a moderate degree of lobular and ductal reduction, whereas MK386 caused only ductal regression. Reduction of BrdU-positive cells in the sebaceous lobes was found in the skin treated with finasteride and RU58841. Serum concentrations of testosterone and dihydrotestosterone showed no significant changes in all drug-treated rats. The weight of the prostatic lobes was reduced significantly in rats treated with finasteride but not by the other two agents. RU58841 effectively counteracted endogenous androgens resulting in a suppression of growth of the sebaceous glands but not the prostate. This rodent model for androgen-dependent hyperplasia of the sebaceous glands is useful for the study of many pharmacological aspects comprising the rate of percutaneous absorption, stability and affinity to target organs of the testing compounds, and selection of adequate vehicle for topical application.

Diffuse Sebaceous Gland Hyperplasia

We report a 43-year-old woman with sebaceous gland hyperplasia that occurred in a diffuse pattern of aggregated papular lesions involving her entire face, neck, and upper chest. Comedones, pustules, and inflammatory papules were absent. The eruption was accompanied by marked seborrhea. Histopathological examination showed enlargement of sebaceous acini, an increased number of immature sebocytes in foci, and a dilated follicular infundibulum. Immunohistochemical investigation showed cytokeratin 14 (CK 14) expression in the keratinocytes of the infundibulum, the isthmus, and sebaceous duct and in the mature and immature sebocytes; CK 17 expression in the keratinocytes of the sebaceous duct; CK 1 expression in the keratinocytes of the infundibulum; and an enhanced expression of the proliferation cell antigen Ki-67 (MiB1) in the immature sebocytes. With CK 18 and CK 19, no staining was observed. Oral therapy with isotretinoin (13-cis-retinoic acid) resulted in remarkable improvement in < or = 3 months. Histopathological and immunohistochemical examination after therapy showed markedly reduced sebaceous glands, a decrease in the staining of MiB1-positive immature sebocytes, and enhanced expression of CK 19 in immature sebocytes and sebaceous duct cells. Diffuse sebaceous gland hyperplasia is a rare variant of seboglandular proliferative disorders that is distinct from the well-known circumscribed type.

IMMUNOHISTOCHEMICAL EXPRESSION OF KERATIN PROTEINS IN KERATOACANTHOMAS OF THE SKIN

Keratin expression in eight cases of keratoacanthoma was examined immunohistochemically using a panel of seven monoclonal antibodies to either single or a few subsets of keratin polypeptides, and compared with normal surrounding skin to evaluate their cell phenotypes. Six cases of squamous cell carcinoma of the skin were also examined. In outer root sheath cells of normal hair follicles, all the cells were immunopositive with E3, CK8.12 and 312C8-1 antibodies, limited reactivity was seen at the level of sebaceous duct insertion with 34 beta B4, and restricted expression was seen at the early anagen stage with KS-1A3, while all cells were totally immunonegative with RPN1165 and CK4.62. In all eight keratoacanthomas studied, 312C8-1 immunorectivity was seen in peripheral basaloid cells of the endophytic lobules, E3, CK8.12 and 34 beta 4 immunoreactivity was found in centrally located cells with glassy appearance, while RPN1165 and CK4.62 gave no immunoreaction. In one case, glassy type cells were positive with KS-1A3. These results suggest that keratin expression in keratoacanthomas resembles that in the upper part of the outer root sheath cells of the hair follicle, and suggest the possible origin of keratoacanthoma cells from those of the outer root sheath. However, similar keratin expression was found in squamous cell carcinomas of the skin and we were unable to distinguish these two conditions from their keratin reactivity.

Microcystic adnexal carcinoma of the skin: A reappraisal of the differentiation and differential diagnosis of an underrecognized neoplasm

Microcystic adnexal carcinoma (MAC) is a locally aggressive adnexal neoplasm whose histogenesis is disputed. Many cases referred to us had been misdiagnosed. Our purpose was to clarify the differential diagnosis and differentiation of MAC. We sought follow-up data and examined routinely stained sections from 17 cases. We performed immunoperoxidase stains for carcinoembryonic antigen, pilar keratin (AE13), proliferating cell nuclear antigen (PCNA), type IV collagen, p53, and CD34 on selected cases. Nine biopsy specimens had initially been misinterpreted. Cysts containing compact keratin or shadow cells were present in 11 cases, which we interpret as evidence of follicular differentiation. Sebaceous gland and duct as well as inner root sheath structures were seen in one case each. CD34 did not mark the clear cells as it does those of the outer root sheath. Staining for PCNA, type IV collagen, and p53 did not distinguish MAC from benign adnexal neoplasms. MAC can be distinguished from its simulants in adequate biopsy specimens. Incompletely excised lesions usually recur. Both follicular and sudoriforous differentiation is present. Type IV collagen, PCNA, and p53 antisera were not useful in differential diagnosis.

KERATIN PHENOTYPES IN BASAL-CELL CARCINOMAS OF THE SKIN

Immunohistochemical profiles of 23 cases of basal cell carcinoma (BCC) were examined and compared with adjacent normal skin using three keratin antibodies, 34betaB4, 312C8-1 and E3, which recognize keratin 1, 14 and 17, respectively. In normal skin, 34betaB4 was expressed in suprabasal cells of the epidermis, sebaceous duct cells and the outer root sheaths of hair follicles at the level of sebaceous duct insertion. 312C8-1 was seen in basal cells of the epidermis, the outer root sheaths of hair follicles, and the peripheral cells of sebaceous glands. E3 was detected in the outer root sheaths of hair follicles, and the peripheral cells of sebaceous glands, while it was absent in the epidermis. In BCC, 312C8-1 and E3 were homogeneously found in all 23 cases, and 34betaB4 was sporadically expressed in 3. Therefore. the results suggest that the keratin expression of BCC resembles that of the pilosebaceous apparatus.

Lectin‐binding profiles for normal skin appendages and their tumors

A histochemical investigation of lectin-binding sites was carried out on formalin-fixed paraffin-embedded sections of 60 skin appendage tumors and adjacent normal skin appendages, using four different biotinylated lectins, peanut agglutinin (PNA), Dolichos biflorus agglutinin (DBA), soybean agglutinin (SBA), and Ulex europaeus agglutinin-1 (UEA-1), and avidin-biotin-horseradish peroxidase labeling. In the secretory segments of eccrine sweat glands, the superficial dark cells showed strong cytoplasmic staining with UEA-1, whereas DBA and SBA strongly stained the plasma membranes of basal clear cells. The acinar cells of apocrine sweat glands revealed sporadic apical membrane staining with all four lectins. In some cases, the luminal membranes of sweat gland ducts showed apical membranous staining with all four lectins. In the hair follicles, the inner root sheath was positive for all four lectins, and the outer root sheath was stained by PNA. The sebaceous ducts, as well as the outer root sheath at the level of sebaceous duct insertion, were also labeled by all four lectins. Sebaceous lobules showed cytoplasmic and membrane staining of mature sebocytes with PNA and SBA. Although sweat gland tumors revealed differences in lectin binding when compared to their corresponding normal tissues, the lectin-binding pattern of pilosebaceous tumors was analogous to the pilosebaceous apparatus.

Selective Involvement of Keratins K1 and K10 in the Cytoskeletal Abnormality of Epidermolytic Hyperkeratosis (Bullous Congenital Ichthyosiform Erythroderma)

Aggregation of tonofilaments within epidermal keratinocytes is a characteristic histologic feature of epidermolytic hyperkeratosis including the generalized form known as bullous congenital ichthyosiform erythroderma. The histologic distribution and the keratin composition of the altered tonofilaments were investigated to determine whether the aggregation was specific to any particular keratin(s). Skin samples from seven patients and one mid-trimester fetus with generalized epidermolytic hyperkeratosis, and from one patient with a localized or "nevoid" form of epidermolytic hyperkeratosis, were analyzed by using various microscopical and immunocytochemical methods. A conjunctival sample and cultured epidermal keratinocytes from one patient with generalized epidermolytic hyperkeratosis were also examined by electron microscopy and immunocytochemistry. Ultrastructurally, tonofilament aggregates were distributed within the suprabasal stratified epithelial cell layers of the epidermis, of the infundibular part of outer root sheaths, and of the sebaceous ducts and sweat ducts, selectively following the known distribution pattern of keratins K1 and K10. The abnormal tonofilaments were not found in any other cutaneous epithelia, in conjunctival epithelium, or in cultured keratinocytes, where K1 and K10 are absent or only minimally expressed. Immunoelectron microscopy showed that among the keratins detected in suprabasal epidermolytic hyperkeratosis epidermis (K1/K5/K10/K14/K16), the aggregated tonofilaments predominantly expressed K1 and K10 rather than other keratins. These results suggest that the keratin filament abnormality in epidermolytic hyperkeratosis principally involves K1 and K10 and raise the question whether epidermolytic hyperkeratosis might be primarily a disorder of one or both of these keratins.

Immunohistochemical differentiation of basal cell epithelioma from cutaneous appendages using monoclonal anti-glycoprotein antibody TNKH1: Its application in Mohs' micrographic surgery

TNKH1, which was primarily developed to detect differentiated melanocytic tumor cells, was found to recognize basal keratinocytes of hair follicle and some basal keratinocytes of human epidermis. Thus, TNKH1 decorated the basal cells of following structures: epidermis (39 of 54, only part of each specimen [OPES]), upper hair follicle (one of 24, OPES), lower hair follicle (21 of 21, very high rate of each specimen [VHES]), sebaceous duct (14 of 15, VHES), sebaceous gland (ten of 14, germinative cells near duct), eccrine duct (three of 19, OPES). Epithelial tumors, considered to be derived from or differentiating toward hair follicle such as trichilemmoma (one of one, VHES) and basal cell epithelioma (BCE) (32 of 32, VHES) were labeled not only in the peripheral cells but in their entirety. On the other hand, epidermal tumors, such as seborrheic keratosis (ten of 11, OPES), actinic keratosis (two of three, OPES), and squamous cell carcinoma (one of two, OPES), showed an irregular peripheral basal cell staining as in normal epidermis. The apocrine sweat apparatus and eccrine secretory portion were negative. Eccrine ductal tumors such as syringoma (two tested), eccrine acrospiroma (one), and eccrine carcinoma (two) were TNKH1 negative. Taking advantage of this total labeling of BCE versus peripheral labeling of the hair follicle, the authors could distinguish BCE tissue from other structures clearly. Among confusing structures the upper hair follicle and the eccrine duct were excluded easily because of their negative staining with TNKH1. The lower hair follicle was TNKH1 positive but only in the outer basal layer, whereas the BCE was TNKH1 positive in its entire basaloid cells. The result indicated that TNKH1 will be a useful antibody in Mohs' micrographic surgery.

Eruptive Vellus Hair Cysts. A Follicular Cyst of the Sebaceous Duct (Sometimes)

Eruptive Vellus Hair Cysts. A Follicular Cyst of the Sebaceous Duct (Sometimes)