Involucrin expression in skin appendage tumours

Giant Pilomatrixoma of the Scrotum: A Rare Case Presentation

Pilomatrixoma is a benign adnexal skin tumor involving the hair follicle matrix. It is found in children, predominantly involving the face. We report here an interesting and rare case of a 52-year-old male presenting with a large, firm, and painless mass over the scrotum considered to be a sebaceous cyst. The mass was completely excised and a biopsy report revealed it to be a pilomatrixoma of the scrotum. The patient recovered well postoperatively with no recurrence over two years.

Pale (Clear) Cell Acanthoma of the Palate

Clear cell acanthoma (CCA), also known as pale cell acanthoma, represents a rare benign epidermal tumor with strong predilection for the lower extremities of middle-aged individuals and no frank gender preference. The etiology of CCA is poorly understood, although a localized psoriasiform reaction is favored. Herein, we report on the clinicopathologic and immunohistochemical features, and HPV status of an apparent example of oral CCA. A 58-year-old female presented with a well-circumscribed, asymptomatic, exophytic, sessile and erythematous nodule of the right hard palate, measuring 0.7 cm in greatest dimension. Microscopically, the lesion featured parakeratosis and acanthosis with neutrophilic microabscesses and broad elongated rete pegs. In areas, spinous epithelial cells exhibited pale or clear cytoplasm without nuclear pleomorphism, mitoses or cytologic atypia. The supporting connective tissue revealed mild chronic inflammation with few scattered neutrophils and numerous capillary vessels. PAS histochemical stain with and without diastase disclosed the presence of cytoplasmic glycogen in the pale cells. The majority of glycogen-rich epithelial cells stained strongly for EMA and were negative for D2-40. Ki-67 immunostaining was confined only to the basal cell layer of the epithelium. A diagnosis of CCA was rendered. The lesion was negative for human papillomavirus (HPV) infection, as assessed by HPV-DNA PCR using the MY09/11 primers for the L1 conserved region, thus HPV infection does not appear to contribute to the pathogenesis of oral CCA. In conclusion, we report an intraoral example of CCA in order to raise awareness about this entity.

Epithelioma of Malherbe: new ultrasound patterns

Backround

Calcifying epithelioma of Malherbe, or Pilomatricoma, is considered an uncommon cutaneous neoplasia, normally occurring in children as a solitary, firm, asymptomatic, hard, subcutaneous, slowly growing nodule on the face, neck, or proximal upper extremity. In literature, two Pilomatricoma ultrasound patterns are described: the totally calcified nodule and the hypoechoic nodule with internal calcific foci. High frequency ultrasound has not yet been applied for routine diagnosis of Pilomatricoma. The aim of the study was to retrospectively identify specific ultrasound features.

Methods

We retrieved 124 histologically Pilomatricoma cases: 28 patients with 32 lesions were preoperatively evaluated with ultrasound.

Results

22/32 have shown a solid formation, hypoechoic, with a sharp outline. Of these 22, 10 lesions were completely calcifying and 12 partially calcified. In 3/32 lesions with uncertain diagnosis, ultrasounds showed a complex/mixed pattern with pseudo-fluid areas and microspots. 7/32 lesions with US different diagnosis included 3 complex lesions, 2 cystic lesions and 2 solid nodular lesions.

Conclusion

In addition to well-known ultrasound patterns (completely calcified and partially calcified) we identified three new, not yet described, patterns that constitute the 31% of the cases: complex, pseudocistyc and pseudotumoral.

Keratins of the Human Hair Follicle

Substantial progress has been made regarding the elucidation of differentiation processes of the human hair follicle. This review first describes the genomic organization of the human hair keratin gene family and the complex expression characteristics of hair keratins in the hair-forming compartment. Sections describe the role and fate of hair keratins in the diseased hair follicle, particularly hereditary disorders and hair follicle-derived tumors. Also included is a report on the actual state of knowledge concerning the regulation of hair keratin expression. In the second part of this review, essentially the same principles are applied to outline more recent and, thus, occasionally fewer data on specialized epithelial keratins expressed in various tissue constituents of the external sheaths and the companion layer of the follicle. A closing outlook highlights issues that need to be explored further to deepen our insight into the biology and genetics of the hair follicle.

On the regulation of hair keratin expression: lessons from studies in pilomatricomas

Human hair follicles exhibit a complex pattern of sequential hair keratin expression in the hair matrix, cuticle, and cortex. In pilomatricomas, that is, benign skin tumors thought to arise from germinative matrix cells of the hair follicle and retaining morphological signs of cortical differentiation, this differential hair keratin pattern has been shown to be faithfully preserved in the lower and upper transitional cell compartments of the tumors. Here we show that also the co-expression of hair keratin hHa5 with its regulatory nuclear homeoprotein HOXC13 in matrix cells of the hair follicle is maintained in lower transitional cells of pilomatricomas. In contrast, the nuclear co-expression of LEF1 and beta-catenin, which in the hair follicle has been postulated to initiate cortex cell differentiation through the induction of hair keratin hHa1 expression (Merill et al, Genes Dev 15:1688-1705, 2001), is not preserved in upper transitional cells of pilomatricomas. Although these cells correctly express hHa1, they are completely devoid of LEF1 and nuclear LEF1/beta-catenin co-expression is shifted to a subpopulation of hair keratin-free basaloid cells of the tumors. These data imply that unlike the normal hair follicle, cortical differentiation in pilomatricomas is not under the control of the canonical Wnt signaling pathway.

Trichoblastoma and basal cell carcinoma are neoplasms with follicular differentiation sharing the same profile of cytokeratin intermediate filaments

Trichoblastoma and nodular basal cell carcinoma are generally held to be distinctive epithelial neoplasms with some overlapping features. We investigated 30 trichoblastomas in which the basaloid cells expressed cytokeratins (CK) CK5/6, CK14, CK17, CK19, and, in a few cells, vimentin. The cells of the periphery of small and large cysts showed the same profile. Cells lining the lumen of small cysts expressed CK14, CK17, and involucrin, and those in larger cysts showed a positivity for CK1, CK4, CK10, CK14, CK17, and involucrin. The remaining tested antibodies (CK7, CK8, CK13, CK18, CK20, alpha-smooth-muscle actin) were negative in all cases. The cells of the stroma expressed vimentin and in 22 cases, the CD34 antigen. Seventeen nodular basal cell carcinomas showed exactly the same staining pattern. Furthermore, there are striking immunohistochemical similarities between the neoplastic basaloid cells of both neoplasms and the cells of the hair germ. Therefore, trichoblastoma and nodular basal cell carcinoma cannot be distinguished by their pattern of cytokeratin expression in paraffin sections. The virtually identical cytokeratin pattern seen in trichoblastoma, basal cell carcinoma, and the developing fetal hair follicle is compelling evidence for common differentiation pathway.

The role of keratin proteins and their genes in the growth, structure and properties of hair

The importance of wool in the textile industry has inspired extensive research into its structure since the 1960s. Over the past several years, however, the hair follicle has increased in significance as a system for studying developmental events and the process of terminal differentiation. The present chapter seeks to integrate the expanding literature and present a broad picture of what we know of the structure and formation of hair at the cellular and molecular level. We describe in detail the hair keratin proteins and their genes, their structure, function and regulation in the hair follicle, and also the major proteins and genes of the inner and outer root sheaths. We discuss hair follicle development with an emphasis on the factors involved and describe some hair genetic diseases and transgenic and gene knockout models because, in some cases, they stimulate natural mutations that are advancing our understanding of cellular interactions in the formation of hair.

Pilomatrix carcinoma with multiple visceral metastases. Report of a case

BACKGROUND

The malignant variant of pilomatrixoma is pilomatrix carcinoma, a low-grade, malignant lesion with a tendency to recur. Only three cases with visceral metastases, occurring some years after primary diagnosis, have been reported.

METHODS

A case of metastatic pilomatrix carcinoma of the neck in a patient, age 50 years, is presented.

RESULTS

Histologic examination of the cutaneous lesion showed a dense infiltrate of basaloid cells, an abrupt transition to shadow cells, and central necrosis. Two months after primary diagnosis, pulmonary and brain metastases developed. Despite chemotherapy and irradiation, the patient died a widespread disease 18 months after the primary diagnosis. An autopsy confirmed the diagnosis of pilomatrix carcinoma with metastases to several organs including the heart, lung, brain, liver, pancreas, kidney, adrenal gland, gastric and colorectal submucosa, skin, and bone.

CONCLUSIONS

Pilomatrix carcinoma is very rare and usually behaves like a low-grade, malignant lesion with a tendency to recur. This patient's tumor is unique because of its highly aggressive behavior and visceral metastases.

Desmoplastic trichoepithelioma of the upper lip. A case report with histochemical features and observations on its histogenesis

A case of desmoplastic trichoepithelioma of the upper lip investigated by histochemistry and immunocytochemistry is presented. There was histologic suggestion of cytoplasmic vacuolation that does not appear to have been previously described. Histochemical examination indicated the presence of glycogen within tumor cells and a reparative-type stroma. Immunocytochemical examination revealed variable reactivity for high molecular weight cytokeratin and colonization by Langerhans' cells. The observations suggest a follicular and sudoriferous differentiation for desmoplastic trichoepithelioma and hence an origin from a pluripotential adnexal keratinocyte.

Involucrin mRNA is more abundant in human hair follicles than in normal epidermis

Involucrin is a precursor protein of the cornified cell envelope in epidermal keratinocytes, where it has been located by immunohistochemistry in the upper spinous and granular layers of human epidermis. In the hair follicle, involucrin has been found in the inner root sheath and in the upper layers of the infundibulum and the isthmus (upper outer root sheath), whereas its presence in the lower outer root sheath and the cortex has been controversial. Therefore, we analyzed the distribution of involucrin mRNA in adult scalp by Northern blotting and in situ hybridization. Northern blots showed more abundant involucrin mRNA in the follicular fraction than in the epidermal fraction of dissected scalp. In situ hybridization matched the immunohistologic results; transcripts of involucrin were expressed not only in the infundibulum and isthmus, but also in the hair cortex and medulla, in all layers of the inner root sheath, and in the inner cells of the lower outer root sheath (all of which lack a cell envelope at the ultrastructural level). However, involucrin was absent in the hair cuticle, which is the only compartment of the follicle possessing a morphologically distinct cell envelope. Our results suggest, first, that involucrin does not serve as a precursor protein of the cornified cell envelope in adult hair follicles, and second, that it is perhaps not necessary for the formation of the cell envelope in keratinocytes of the hair cuticle, as we did not find this precursor protein with highly sensitive methodology.

Tissue- and stratum-specific expression of the human involucrin promoter in transgenic mice

Involucrin is a marker of keratinocyte terminal differentiation and is expressed only in the suprabasal layers of stratified squamous epithelium. In a previous study with various cell types in culture, we noted that expression of the putative human involucrin promoter was keratinocyte specific. To determine if this promoter is sufficient to direct expression to the suprabasal cells of stratified squamous epithelia in vivo, we have now generated transgenic mouse lines harboring the involucrin promoter sequences linked to a beta-galactosidase reporter gene. In the resulting lines, beta-galactosidase was expressed in the suprabasal compartment of stratified squamous epithelia and in hair follicles in a tissue-specific manner. In the palate, distinct vertical stacks of beta-galactosidase-expressing cells were present, suggesting movement of clonally derived cells through the epithelium. The involucrin gene has a single intron upstream of the translational start site, and removal of this intron did not affect tissue- or stratum-specific expression. These results show that the 3.7-kb involucrin upstream sequences contain all the information necessary for a high level of tissue- and stratum-specific expression.

Expression patterns of loricrin in various species and tissues

In this study we analyzed the expression patterns of loricrin in various species and tissues using immunohistochemistry, immunoblotting and Northern blots. Loricrin is a glycine-, serine- and cysteine-rich protein expressed very late in epidermal differentiation in the granular layers of normal mouse and human epidermis. Later on in differentiation, loricrin becomes crosslinked as a major component into the cornified cell envelope by the formation of N epsilon-(gamma-glutamyl)lysine isopeptide bonds. This process either occurs directly or by the intermediate accumulation in L-keratohyaline granules of mouse epidermis and human acrosyringia. Loricrin was identified in all mammalian species analyzed by virtue of its highly conserved carboxy-terminal sequences revealing an electric mobility of approximately 60 kDa in rodents, rabbit and cow and of approximately 35 kDa in lamb and human on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Loricrin is expressed in the granular layer of all mammalian orthokeratinizing epithelia tested including oral, esophageal and fore-stomach mucosa of rodents, tracheal squamous metaplasia of vitamin A deficient hamster and estrogen induced squamous vaginal epithelium of ovary ectomized rats. Loricrin is also expressed in a few parakeratinizing epithelia such as BBN [N-butyl-N-(4-hydroxybutyl)nitrosamine]-induced murine bladder carcinoma and a restricted subset of oral and single vaginal epithelial cells in higher mammals. Our results provide further evidence that the program of squamous differentiation in internal epithelia of the upper alimentary tract in rodents and higher mammals differ remarkably. In addition, we also have noted the distinct distribution patterns of human loricrin and involucrin, another major precursor protein of the cornified cell envelope.

Tissue-specific and differentiation-appropriate expression of the human involucrin gene in transgenic mice: an abnormal epidermal phenotype

Involucrin is a precursor of the keratinocyte cornified envelope that is specifically expressed in the suprabasal layers of the epidermis and other stratifying squamous epithelia. To study involucrin gene expression and the function of involucrin, we expressed a 6 kb DNA fragment of the human involucrin gene, containing approximately 2.5 kb of upstream sequence and 0.5 kb of downstream sequence, in transgenic mice. The transgene produces a 68 kDa protein that is detected by a human involucrin-specific antibody, and is expressed in a tissue-specific and differentiation-appropriate manner (i.e., expression is confined to the suprabasal layers of the epidermis, extocervix, trachea, esophagus and conjunctiva). Soluble involucrin levels are two to four times higher in transgenic epidermal keratinocytes compared to human foreskin keratinocytes. Newborn heterozygous animals have a normal birth weight and a normal appearing epidermis and hair growth begins at 4 to 5 days of age (i.e., the same time as hair growth in non-transgenic animals). In a subpopulation of the newborn homozygous animals birth weight is reduced, the epidermis is scaly and hair growth begins late, at around 9 to 10 days of age. In addition, the hair tends to stand erect on both heterozygous and homozygous adult animals giving the appearance of diffuse alopecia. Immunofluorescent and electron microscopy localize involucrin in the hair follicle and cornified envelope, respectively. These results suggest that overexpression of involucrin may cause abnormalities in hair follicle structure/function and cornified envelope structure. These animals provide a new model for the study of cornified envelope structure and function.

Involucrin expression in some oral lichenoid lesions

The aim of this investigation was to assess the reproducibility of a study which reported that involucrin could be used as a diagnostic marker in oral lichenoid lesions. Twenty-eight formalin-fixed, paraffin-embedded specimens were examined. They included tissue from 13 patients with lichen planus, 11 with drug-related lichenoid reactions, one with dysplasia in a lichenoid lesion and three with normal oral mucosa. In each case the biopsy site was the buccal mucosa, PAS stained smears for fungi were negative and immunofluorescence results supported the diagnosis. An immunoperoxidase technique was used to demonstrate involucrin reactivity. In all sections there was consistent positive staining for involucrin in the superficial layers of the epithelium and all the basal layers were negative. In conclusion there were no demonstrable differences in the involucrin reactivity between the different lesions.

Morphogenesis of the cornoid lamella: histochemical, immunohistochemical, and ultrastructural study of porokeratosis

To elucidate the morphogenesis of cornoid lamellae (CL) in porokeratosis, skin lesions of three cases of disseminated superficial actinic porokeratosis and a case of linear porokeratosis were examined. By N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide staining, SH groups were present in the living layer of the epidermis beneath CL and irregularly disappeared at the bottom of CL, whereas SS linkages appeared in dyskeratotic cells in the living layer and in the irregularly shaped cell membranes of the horny cells. Epidermis beneath CL showed an increased and irregular involucrin expression. Ultrastructurally, the living keratinocytes contained many cytoplasmic vacuoles and had a smaller number of lamellar bodies than normal. Intercellular lamellar sheets were incompletely formed. The dyskeratotic cells and the lower horny cells contained many small vacuoles but formed a marginal band. The horny cells of CL also formed a marginal band and, further, a keratin pattern. CL may be formed by hyperproliferative atypical kertatinocytes which keratinize rapidly and irregularly and show defective desquamation due to the paucity of intercellular lamellar sheets.

Immunohistochemically detectable duct-like structures in benign and malignant eccrine poromas: CEA and involucrin immunostaining

The duct-like structures present in 7 cases of benign and malignant eccrine poroma were examined by immunohistochemical staining for carcinoembryonic antigen (CEA), involucrin, and S-100 protein. The demonstration of CEA and involucrin was helpful in the recognition of these structures. The overt immunopositivity precedes morphological evidence for duct formation. On the basis of the CEA immunostaining, the duct-like structures were divided into 4 types: 1) mature acrosyringeal structure, 2) cystic luminal structure lined by elongated cells, 3) immature acrosyringeal structure, and 4) vacuole- or dot-like potential lumen in a single cell. Involucrine was observed in the lining cells of 1) and 2). None of the 4 types showed positive reactivity for S-100 protein, suggesting the irrelevance of these structures to the secretory element of sweat gland. The polymorphism of the ductal formation tended to be more remarkably observed in malignant eccrine poromas than in the cases of benign eccrine poroma and poroepithelioma tested.

Outer root sheath cells of human hair follicle are able to regenerate a fully differentiated epidermis in vitro

During wound healing, interfollicular epidermis can be regenerated from the outer root sheath of hair follicles, showing that the cells of this structure can shift toward an interfollicular epidermal phenotype. Similarly, it has been shown that a multilayered epithelium originating from outer sheath cells can be obtained in vitro by culturing hair follicles. However, in the culture systems developed so far, the phenotypical shift was incomplete since the cells retained some of their original characteristics and did not acquire several key markers of terminally differentiated epidermis. In this paper, we describe a new tissue culture method for obtaining a multilayered epithelium from outer sheath cells. This is performed by implanting human hair follicles vertically into dermal equivalents and then raising the culture at the air-liquid interface. The morphological, immunological, and biochemical features of the in vitro reconstructed tissue are very similar to those observed in normal interfollicular epidermis, including those specific for terminally differentiated keratinocytes. Thus, under appropriate in vitro conditions, outer root sheath cells are able to express an interfollicular epidermal phenotype as occurs in vivo during wound healing.

Opposite effects of EGF on involucrin accumulation of A431 keratinocytes and a variant which is not growth-arrested by EGF

The A431 cell line is composed of malignant keratinocytes derived from a vulval epidermoïd carcinoma. These cells have the peculiarity to stop their proliferation when they are treated with physiological concentrations of EGF, which is a mitogen for normal keratinocytes. We reported earlier that EGF induces involucrin accumulation in A431 cells and proposed that the arrest of proliferation triggers differentiation as shown by the induction of this cornified envelope precursor protein. To test this hypothesis, we compared the A431 subclone 15, which is not growth arrested by EGF-treatment, to the parental A431 cells. We found indeed that EGF reduces the involucrin content of clone 15 cells in a dose dependent manner. These opposite effects of EGF on the expression of terminal differentiation marker involucrin in A431 and A431 clone 15 keratinocytes were observed in defined medium as well as in presence of fetal calf serum. Nevertheless, when growth of parental A431 cells was inhibited by treatment with TGF-beta or simply when cultures reached confluency, no involucrin accumulation was observed. Therefore growth arrest per se is not directly correlated with the induction of differentiation.

Cytokeratin analysis of pilomatrixoma: changes in cytokeratin-type expression during differentiation

The various structural components of pilomatrixoma (calcifying epithelioma of Malherbe) were studied for the expression of hair-specific (trichocytic) cytokeratins as well as epithelial cytokeratins, using immunoperoxidase and immunofluorescence microscopy of frozen sections as well as two-dimensional gel electrophoresis and immunoblotting. Trichocyte-type cytokeratins were detected in only a minor subpopulation of basophilic cells but more prominently in most "transitional" cells as well as in "shadow" cells. In contrast, antibodies against certain epithelial cytokeratins (including antibody KA1 against cytokeratins of stratified squamous epithelia and antibodies against cytokeratin 19) revealed an extensive but heterogeneous staining of basophilic cells. In regions of squamoid cells, epithelial cytokeratins in an unusual pattern were found. An antibody against vimentin was negative on pilomatrixoma cells. An antibody against desmoplakins decorated true desmosomes in basophilic and transitional cells. Biochemically, trichocytic cytokeratin polypeptides as well as epithelial cytokeratins 5, 6, 14, 16, 17, and 19 were positively detected. These results provide evidence in support of the notion of a trichocytic differentiation and probably derivation of pilomatrixoma. According to the cytokeratin expression patterns the majority of pilomatrixoma cells resemble the normal hair cortex lineage but some enter a pathway of squamous cell differentiation.

Two cases of clear cell acanthoma: an immunohistochemical study

Two cases of clear cell acanthoma are reported. The expression of carcinoembryonic antigen (CEA), involucrin and keratin proteins in the tumors was investigated immunohistochemically. In 1981, Penneys et al. reported that this tumor was not of sweat gland origin because of the absence of CEA. This study confirmed this, further, the pattern of positive reaction of involucrin also indicated that this tumor is not of sweat duct origin.