Immunohistochemical assessment of endothelin-1 axis in psoriasis, basal cell carcinoma and squamous cell carcinoma

AIM

Endothelin-1 is an autocrine growth factor for keratinocytes, an effect controlled by its A and B receptors, with no previous comparison of endothelin axis expression in inflammatory and neoplastic skin diseases showing keratinocyte proliferation. The aim of the study was to investigate endothelin-1 axis expression in skin lesions of psoriasis, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC).

METHODS

This study included 40 subjects (8 patients with SCC, 12 patients with BCC, 10 patients with psoriasis, and 10 healthy controls). Biopsies from lesional skin of patients and normal skin of controls were examined immunohistochemically for endothelin-1 and its receptors A and B frequency and grade of expression.

RESULTS

Endothelin-1 and receptor A were detected in all patients with SCC and psoriasis, with a higher frequency and grade of expression than controls and BCC. The frequency of receptor B expression was significantly lower while higher staining grade was found in BCC (8.3%) rather than other studied groups.

CONCLUSION

A comparable higher frequency and grade of expression of endothelin-1 and its receptor A are documented in psoriasis and SCC than in BCC and controls denoting their involvement in keratinocyte proliferation in both diseases. Receptor A is the predominately expressed receptor in psoriasis and SCC.

[Immunohistochemical study of calretinin in normal hair follicles and tumors with follicular differentiation]

BACKGROUND

Selective immunostaining for calretinin labels the innermost layer of the outer root sheath of normal hair follicles, which is difficult to distinguish with hematoxylin-eosin staining.

OBJECTIVE

The aim of this study was to determine whether immunohistochemistry for calretinin allows identification of cutaneous adnexal tumors with follicular differentiation towards cells of the outer root sheath.

MATERIAL AND METHODS

We analyzed the staining pattern for calretinin by immunohistochemistry in 49 biopsies of cutaneous adnexal tumors with follicular differentiation.

RESULTS

Fifteen biopsies corresponded to trichilemmomas/inverted follicular keratosis and had staining for calretinin in the epithelium of the most superficial areas of the lesions and in squamous eddies. Ten were trichilemmal cysts, which displayed staining of the cyst wall. Three were basal cell carcinomas with variable staining according to the type of follicular differentiation in each variant. One was a panfolliculoma that had focal staining. Two were folliculosebaceous cystic hamartomas with staining of the excretory duct of the sebaceous glands. Two pilomatricomas and 3 proliferative trichilemmal tumors had positive staining in the cellular layers close to the lumen of the cystic structures. Nine trichoblastomas/trichoepitheliomas, 2 infundibular cysts, 1 dilated pore of Winer, and 2 acanthomas of the follicular sheath were negative for calretinin.

CONCLUSION

Immunohistochemistry for calretinin allows identification of cutaneous adnexal tumors of the hair follicle or a component of the follicle with differentiation towards cells of the outer root sheath.

Predominance of the basal type and HER-2/neu type in brain metastasis from breast cancer

Although breast cancer is the second most common cause of central nervous system (CNS) metastases with a notable increase of incidence, only few studies on brain-metastasizing breast cancer are available. In this immunohistochemical and fluorescence in situ hybridization (FISH) study, metastases to the CNS (n=85) and primary breast cancers, with known involvement of the CNS (n=44) including paired primary and metastasized tumours (n=23), were investigated retrospectively for the expression of oestrogen- (ER) and progesterone- (PR) hormone receptors, Her-2/neu, epidermal growth factor receptor (EGFR), Ki-67, and cytokeratins (CKs) 5/14. The majority of brain metastases were steroid hormone receptor negative (ER 66%, PR 82%) corresponding to the findings in primary tumours with known involvement of the CNS (68% ER-negative, 75% PR-negative). The frequency of HER-2/neu-overexpressing or -amplified cancers was increased in both groups (34 and 32%, respectively). EGFR expression was more frequent in metastases (41%) than in primary tumours (16%). The proportions of cases with a basal phenotype were 26 and 30%, respectively. In paired primary tumours and metastases to the CNS, constancy of Her-2/neu status was observed in 87% of cases with only one sample turning Her-2/neu-negative and two samples acquiring overexpression/amplification in brain metastases. In contrast, steroid hormone receptors exhibited more frequently a loss of expression (17%) than a gain (9%) with 74% revealing a constant phenotype. We conclude that brain-metastasizing breast cancer belongs predominantly to the basal type or Her-2/neu type. Primary and metastatic tumours differ from each other only in a minority of cases, leading rather to a loss of steroid hormone receptors and to a gain of EGFR and Her-2/neu.

Rippled-Pattern Sebaceoma: A Report of a Lesion on the Back With a Review of the Literature

A 68-year-old Japanese man presented with a nodule that had been present for 5 to 6 years on the right side of the back. Physical examination revealed a dome-shaped, 12 x 13-mm, dark red nodule. It was excised with a 2 to 3-mm margin. The patient remained free of disease during 77 months of follow-up. Microscopic examination revealed a bulb-like tumor in the dermis, contiguous with the overlying epidermis. It was composed of small, monomorphous, cigar-shaped basaloid cells in linear, parallel rows, resembling the palisading of nuclei of Verocay bodies, and presenting a rippled-pattern. There were scattered cells showing sebaceous differentiation with vacuolated cytoplasm and scalloped nuclei. There were tiny, duct-like spaces. The tumor revealed characteristics of rippled-pattern sebaceoma. The present case is the first reported rippled-pattern sebaceous neoplasm on the back. Many spindle cell tumors, such as basal cell carcinoma, pleomorphic adenoma, dermatofibrosarcoma protuberans, myofibroblastoma, and leiomyoblastoma, in addition to trichoblastoma and sebaceoma, can have a rippled-pattern.

Expression profile of Eph receptors and ephrin ligands in human skin and downregulation of EphA1 in nonmelanoma skin cancer

Eph receptors and ephrin ligands represent the largest family of receptor tyrosine kinases. Beyond their well-defined meaning in developmental processes, these molecules also have important functions in adult human tissues and cancer. However, the Eph/ephrin expression profile in human skin is only marginally studied. We therefore investigated the mRNA expression of 21 Eph receptors and ephrin ligands in adult human skin in comparison to 13 other adult human tissues using quantitative real-time RT-PCR. In addition, immunohistochemistry was established for some members (EphA1, EphA2 and EphA7) to confirm the results of the RT-PCR and to identify the expressing cells in the skin. We found all investigated family members expressed in human skin, but at highly varying levels. EphA1, EphB3 and ephrin-A3 turned out to be most prominently expressed in skin compared to other adult human tissues. EphA1 was exclusively expressed in the epidermis. We therefore investigated the expression of EphA1 in nonmelanoma skin cancers derived from the epidermis (56 basal cell carcinomas and 32 squamous cell carcinomas). As demonstrated by immunohistochemistry, both skin cancers displayed a significant downregulation of EphA1 compared to the normal epidermis. In squamous cell carcinoma, the EphA1 downregulation was associated with increased tumor thickness, although this was not significant. Our results indicate that Eph receptors and ephrin ligands are widely expressed in the adult human skin, particularly in the epidermis, and may play an important role in skin homeostasis. EphA1 seems to be a marker of the differentiated normal epidermis and its downregulation in nonmelanoma skin cancer may contribute to carcinogenesis of these very frequent human tumors. EphA1 represents a new potential prognostic marker and therapeutic target in nonmelanoma skin cancer.

Cystic panfolliculoma

Panfolliculoma is a rare follicular neoplasm with differentiation toward both upper (infundibulum and isthmus) and lower (stem, hair matrix, and bulb) segments of a hair follicle. We present an unusual case of cystic panfolliculoma. A 33-year-old Hispanic woman presented with an 8-month history of a 3.0-cm cystic scalp mass. The lesion was excised, and the histologic sections showed a cystic follicular neoplasm that contained corneocytes in basket-woven and laminated array, trichohyalin granules of the inner root sheath, germinative cells, papillae, matrical cells, and "shadow" cells. Cytokeratin 903 and cytokeratin 5/6 immunostains uniformly highlight the tumor cells. Ber-EP4 strongly labels the germinative cells but not the follicular papillae. CD34 labels the surrounding fibrotic stroma and focally the epithelial component.

Desmoplastic trichilemmoma: a rare tumor of the eyelid

PURPOSE

To report an upper eyelid mass which proved to be a desmoplastic trichilemmoma.

METHODS

A 60-year-old man had a slowly enlarging upper eyelid mass. The tumor was excised. The pathologic evaluation of the tumor was centered on the differential diagnosis.

RESULTS

The clinical appearance of this lesion is nonspecific and can simulate a verruca, follicular keratosis, or basal cell carcinoma. Central desmoplasia, outer root sheath differentiation of the tumor cells, and CD34 positivity are the main characteristics that allow differentiation from basal cell carcinoma.

CONCLUSIONS

Proper recognition of a benign neoplasm that may be misdiagnosed as basal cell cancer can prevent aggressive surgical treatment.

Terahertz pulsed imaging and spectroscopy for biomedical and pharmaceutical applications

Terahertz (THz) radiation lies between the infrared and microwave regions of the electromagnetic spectrum. Advances in THz technology have opened up many opportunities in this scientifically and technologically important spectroscopic region. The THz frequency range excites large amplitude vibrational modes of molecules as well as probing the weak interactions between them. Here we describe two techniques that utilize THz radiation, terahertz pulsed imaging (TPI) and terahertz pulsed spectroscopy (TPS). Both have a variety of possible applications in biomedical imaging and pharmaceutical science. TPI, a non-invasive imaging technique, has been used to image epithelial cancer ex vivo and recently in vivo. The diseased tissue showed a change in absorption compared to normal tissue, which was confirmed by histology. To understand the origins of the differences seen between diseased and normal tissue we have developed a TPS system. TPS has also been used to study solids of interest in the pharmaceutical industry. One particularly interesting example is ranitidine hydrochloride, which is used in treatment of stomach ulcers. Crystalline ranitidine has two polymorphic forms known as form 1 and form 2. These polymorphs have the same chemical formula but different crystalline structure that give rise to different physiochemical properties of the material. Using TPS it is possible to rapidly distinguish between the two polymorphic forms.

Immunohistochemical evaluation of PCNA and Ki-67 in ameloblastoma

Thirty-two ameloblastoma tissues were immunohistochemically studied using monoclonal anti-proliferating cell nuclear antigen (PCNA) and anti-Ki-67 antibodies. Positive cells were evaluated and analyzed in relation to the WHO classification, cytological pattern of the outer layer cell, clinical appearance, tumor location, radiographic appearance and patient's age. In regard to the cytological pattern of the outer layer cells, the basal cell type had significantly higher PCNA and Ki-67 (P<0.05) labeling indices than the cuboidal cell type. The solid type had significantly higher PCNA and Ki-67 (P<0.05) labeling indices than the cystic and the mixed type. The labeling index of the younger patient was found to be the lowest, the middle age was in the middle and the older patient was the highest. These results indicated that the proliferating activities of ameloblastomas are quite variable, and the evaluations of Ki-67 and PCNA seem to be good indicators to assess the proliferating activity of each type of ameloblastomas.

A rippled-pattern trichoblastoma: an immunohistochemical study

BACKGROUND

Since the first description by Hashimoto et al., there have been only a few case reports of rippled-pattern tricogenic tumor. In addition, there are no reports on detailed immunohistochemical analyses of this rare neoplasm. We describe here an additional case of rippled-pattern trichogenic tumor with a special reference to its immunohistochemical features.

METHODS

A nodule arising on the occipital area of a 62-year-old Japanese woman was histologically and immunohistochemically investigated.

RESULTS

Histopathologically, the lesion contained various-sized lobular nests, which consisted of oval to elliptical shaped basaloid cells without any atypia and were embedded in the collagenous stroma. Some elongated basaloid cells were arranged in a palisading fashion forming parallel rows of epithelial ribbons in a rippled-pattern. Cytokeratin (CK) immunohistochemistry showed constant expressions of CK1/5/ 10/14, CK5/8, CK14 and CK7, and focal expressions of CK17 and CK19 in the basaloid cells, suggesting a keratin phenotypical similarity to the cells in small nodular type trichoblastoma.

CONCLUSIONS

The present tumor is a variant of trichoblastoma, and considered to be in close association with the outer root sheath and/ or follicular germinative cells.

Rippled-pattern sebaceous trichoblastoma

BACKGROUND

There is a large spectrum trichoblastoma; of which, several histologic variants have been described including a rippled-pattern variant. Three cases of rippled-pattern trichoblastoma are described which also exhibited definitive foci of sebaceous differentiation.

METHODS

Three cases were retrieved from the archives of the Dermatopathology Laboratory at the University of California Irvine (Orange, CA, USA). All specimens were stained with hematoxylin and eosin (H&E). In addition, sections were submitted for immunohistochemical studies with epithelial membrane antigen (EMA).

RESULTS

All three biopsies were composed of well-circumscribed multiple variously sized tumor lobules present in the upper to deep dermis comprised of with rounded or slightly elongated basaloid cells with scant eosinophilic cytoplasm. The lobules were separated by a slightly hyalinized stroma. The unique finding present in all three specimens was a peculiar arrangement of the basaloid cells in linear rows parallel to one another. This gave the tumors a rippled pattern similar to the palisading of nuclei of Verocay bodies seen in schwannomas. In addition all three biopsies showed definite sebaceous differentiation.

CONCLUSIONS

Three additional cases of rippled-pattern trichoblastoma are presented. All three were located on the scalp and showed additional features of foci of sebaceous differentiation. No associations with Muir-Torre Syndrome were found in these patients. Because this appears to be a distinct variant within the large spectrum of trichoblastoma, the term rippled-pattern sebaceous trichoblastoma is suggested.

Immunohistochemical analysis of cytokeratin expression in various trichogenic tumors

The immunophenotypes, especially expression of cytokeratins, in 13 cases of trichogenic tumors were examined to investigate their histogenesis. Four cases of multiple trichoepithelioma, five cases of classical solitary trichoepithelioma, one case of desmoplastic trichoepithelioma, one case of trichogenic trichoblastoma, one case of trichoblastic fibroma, and one case of giant solitary trichoepithelioma were retrieved. The immunoreactivities of the epithelial nests and the keratinous cysts in these tumors were similar to those of the outer root sheath and the infundibulum of normal hair follicles, respectively. From the comparative studies of the immunophenotypes with those of normal hair follicles, we speculated that all trichogenic tumors differentiate mainly toward the outermost layer of the outer root sheath between the lower part of the permanent portion and the upper part of the transient portion and some parts of them differentiate toward various other parts of the follicles. Although differentiation toward the other follicular structures can vary from case to case, there is no particular staining pattern specific for each kind of trichogenic tumor and no significant differences in immunoreactivity among them. Our observations support a recent notion that all neoplasms of follicular germinative cells should be grouped as a single entity.

An immunohistochemical study of basal cell carcinoma and trichoepithelioma

The histologic distinction between tricheopithelioma and basal cell carcinoma may be difficult in small biopsies. Immunohistochemical stains have been used to help make this distinction; however, published studies have generally been limited to a few antibodies. To this end we performed a comprehensive immunohistochemical analysis of 20 basal cell carcinomas and 10 tricheopitheliomas from our files, in search of a consistent pattern of reactivity to distinguish the neoplasms in biopsies. The antibodies used were: low molecular weight keratin (Cam 5.2), Cytokeratin 7, (CK7), Cytokeratin 20, (CK20), Carcino-embryonic antigen (CEA), CD30 (Ki-1), bcl-2, Ham 56, HPCA-I (CD34), and Ulex Europaeus type I. In our study, bcl-2 stained all but one basal cell carcinoma in a diffuse pattern, whereas all tricheopitheliomas showed staining of the outermost epithelial layer. No other stain proved to be an independent marker for either neoplasm and no consistent immunohistochemical profile for either neoplasm emerged. Thus, we conclude that bcl-2 may be of some value in distinguishing basal cell carcinoma from tricheopithelioma, limited by the quantitative nature of the difference in staining. Histologic criteria applied to H&E-stained sections remain the cornerstone of histologic diagnosis.

Malignant basal cell tumor in a Djungarian hamster

A malignant basal cell tumor was found in the skin of the abdomen of a female Djungarian hamster of unknown age and weighing 40 g. Histologically, the tumor mass was composed of cells resembling the basal cells of the epidermis, and these cells exhibited solid type proliferation. In the tumor tissue and necrotic foci, horn cysts were observed. Immunohistochemically, cytokeratin was present in the tumor cells and horncysts. By electron microscopic examination, the tumor cells had scanty cell organelles and a few desmozomes. This paper describes a rare malignant basal cell tumor in a Djungarian hamster.

The use of immunostaining for bcl-2 and CD34 and the lectin peanut agglutinin in differentiating between basal cell carcinomas and trichoepitheliomas

Fifteen unequivocal basal cell carcinomas (BCC) and ten unequivocal trichoepitheliomas (TE) were studied using the lectin peanut agglutinin (PNA), and the monoclonal antibodies Q bend 10 and bcl-2 oncoprotein directed against the antigens CD34 and bcl-2, respectively, to see whether these markers could be used to differentiate between the two tumors. Ten percent of TE demonstrated a continuous band-like peritumorous staining with PNA and 80% demonstrated a discontinuous band-like peritumorous staining with PNA, with the comparable figures for BCC being 40% and 20%, respectively. In addition, 40% of BCC showed focal areas of pemphigus-like staining in contrast with only 10% of TE. Using the antibody directed against bcl-2, TE demonstrated weak staining mainly confined to the basal layer of tumor cells in 20% of cases and staining of the cells throughout the tumor in 30% of cases. Similarly, BCC also showed staining of the basal layer of tumor cells in 7% of specimens and staining of cells throughout the tumor mass in 40% of specimens studied. Finally, with the antibody Q bend 10 directed against CD34, staining of the immediate peritumoral spindle-shaped cells was observed in 20% of TE compared with 7% of BCC. Despite reports in the literature, we found that none of these three markers can be reliably used to differentiate between TE and BCC.

Stromelysin-3: a potent marker for histopathologic differentiation between desmoplastic trichoepithelioma and morphealike basal cell carcinoma

Histopathological differentiation between desmoplastic trichoepithelioma (DTE) and morphealike basal cell carcinoma (BCC) is a difficult problem because of their similar morphological features. The matrix metalloproteinase stromelysin-3 (ST-3), which is expressed as a specific fibroblastic factor especially surrounding carcinoma cells, was studied in these both conditions of wholly different clinical outcome. Using formalin-fixed paraffin-embedded tissues, we found positive immunoreactivity for ST-3 in fibroblastic cells surrounding morphealike BCC cells in 34 (68%) of 50 cases, whereas the epithelial tumor cells themselves were negative. In none of the 12 cases of DTE did we observe expression of ST-3 in fibroblasts. We conclude that the antibody against ST-3 protein is an immunohistochemical marker to distinguish morphealike BCC from DTE.

Molecular pathology in basal cell cancer with p53 as a genetic marker

Human basal cell cancer (BCC) has unique growth characteristics with virtual inability to metastasize. We investigated clonality and genetic progression using p53 mutations as marker. Sampling was done through microdissection of frozen immunohistochemically stained 16 microm slices of tumors. From 11 BCC tumors 78 samples were analysed. Direct DNA sequencing of exons 5-8 was performed, haplotypes were determined after cloning of p53 exons and loss of heterozygosity (LOH) ascertained by microsatellite analysis. All tumors had p53 mutations and in a majority both p53 alleles were affected, commonly through missense mutations. Microdissection of small parts (50-100 cells) of individual tumors showed BCC to be composed of a dominant cell clone and prone to genetic progression with appearance of subclones with a second and even third p53 mutation. Samples from normal immunohistochemically negative epidermis always showed wild type sequence, except for a case of previously unknown germline p53 mutation. Our analysis also included p53 immunoreactive patches i.e. morphologically normal epidermis with a compact pattern of p53 immunoreactivity. Mutations within those were never the same as in the adjacent BCC. This detailed study of only one gene thus uncovered a remarkable heterogeneity within a tumor category famous for its benign clinical behavior.

Merkel cells are absent in basal cell carcinomas but frequently found in trichoblastomas. An immunohistochemical study

The possibility of a neuroendocrine differentiation in basal cell carcinomas (BCCs) has been a matter of debate for many years. In the present immunohistochemical study, applying the cytokeratins 8, 18 and 20 as the most established markers for Merkel cells (MCs), we did not find elevated numbers of MCs in any of 205 BCCs. This speaks against a neuroendocrine line of differentiation in BCCs. In contrast, we found various amounts of MCs in 15 of 36 trichoblastomas, which are the main benign differential diagnosis of BCC. In 4 trichoblastomas abundant MCs were spread over the whole epithelial tumor area. Additionally, the trichoblastomas' overlying epidermis exhibited significantly much higher numbers of MCs than the uninvolved adjacent skin or the epidermis overlying the BCCs. These findings might be an additional aid in the distinction between trichoblastomas and BCCs. Furthermore, concerning the recent discussion about the role of MC in growth and development of follicular germ, our observations are another sign of regulative influences of the MC, also in follicular germ under pathological conditions. Trichoblastomas with high numbers of MCs could be characterized as showing advanced differentiation toward the neuroendocrine component of the hair follicle, i.e., the MCs.

Epithelial markers and differentiation in adnexal neoplasms of the skin: an immunohistochemical study including individual cytokeratins

Applying immunohistochemical procedures for the detection of eight different cytokeratin (CK) polypeptides and other differentiation markers, we compared the staining patterns of normal cutaneous structures with those of benign adnexal tumors (n = 65). Syringomas exhibited a marker pattern highly reminiscent of that seen in normal dermal eccrine ducts (EMA in peripheral cells, CK 10 in intermediate cells, and CK 6, CK 19, and CEA in luminal cells). Nodular hidradenomas exhibited complex patterns suggesting relationship between tumor cells, including clear cells, and normal secretory coil cells (CK 7, CK 8, CK 19, and EMA); however, dermal-duct and epidermoid differentiation were also detectable. In both cylindromas and spiradenomas, zonal staining patterns were apparent: modified myoepithelial cells were positive for smooth-muscle-type actin, while the luminal cells mainly expressed ductal markers (CK 6 and CK 19) and, less prominently, secretory-coil markers including CK 7. Eccrine poromas exhibited a widespread reaction for CK 5/6 and EMA, analogous to peripheral dermal duct cells, but focal maturation toward inner-ductal and secretory-coil cells was also demonstrable. The staining pattern observed in trichoepitheliomas resembled that of the outer but not the inner root sheath. In conclusion, the detailed marker profiles obtained in the present study have broadened our understanding of the differentiation and nature of these highly singular tumor types.

A nevoid plaque with histological changes of trichoepithelioma and cylindroma in Brooke-Spiegler syndrome. An immunohistochemical study with cytokeratins

Brooke-Spiegler syndrome is characterized by the development of multiple trichoepitheliomas and cylindromas. In addition, multiple spiradenomas have been observed in this autosomal-dominant inherited disease. We report a 53-year-old woman with multiple cylindromas on the head and neck and multiple trichoepitheliomas on the face. Additionally, she had had since birth a plaque on the right side of her neck containing two nodules with features of both cylindroma and trichoepithelioma. Immunohistochemical investigations revealed in the basaloid cells of trichoepithelioma an expression of CK 5/6, CK 14, CK 17, CK 19 and vimentin. The cells of the cylindroma lacked vimentin but expressed additionally CK 7, CK 8 and CK 18. The occurrence of cylindroma and trichoepithelioma in a single nevoid plaque from a patient with Brooke-Spiegler syndrome implies an alteration in the stem cells of the folliculosebaceous-apocrine unit and could be characteristic of the disorder.

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.

Use of CD34 in assessing the relationship between stroma and tumor in desmoplastic keratinocytic neoplasms

It has been hypothesized that the ability for neoplastic growth of epithelial-derived neoplasms depends upon the stroma. There are currently some studies which show that the stroma surrounding basal cell carcinomas (BCC) is derived from the tumor. In contrast, other studies provide evidence that the stroma is a host-derived response to the tumor. In order to further examine the nature of stroma enveloping cutaneous epithelial neoplasms, we examined a series of tumors which contain abundant stroma, including morpheic type BCC (MBCC), desmoplastic trichoepitheliomas (DTE), and microcystic adnexal carcinomas (MAC). The spindle-shaped cells surrounding the epithelial islands of the two malignant tumors, MBCCs and MACs, were negative in 70% and 100% of cases, respectively, for CD34. In contrast, the spindle-shaped cells surrounding the islands of the benign DTEs were positive for CD34 in 80% of cases. The results suggest that whereas stromal cells surrounding DTEs resemble the CD34-positive perifollicular cells, the spindle-shaped stromal cells surrounding MBCC and MAC are CD34 negative, and may be derived from sources other than the normal mesenchymal tissue surrounding cutaneous appendages.

Relative amounts of keratin 17 are higher than those of keratin 16 in hair-follicle-derived tumors in comparison with nonfollicular epithelial skin tumors

Specimens of trichilemmal cyst, malignant trichilemmoma, keratoacanthoma, and epidermal cyst were examined to characterize keratin peptides in hair-follicle-derived tumors. Keratins were extracted from the specimens and analyzed by two-dimensional gel electrophoresis and densitometry; the results were then compared with those for normal epidermis, the outer root sheath of hair follicles, psoriatic epidermis, and various nonfollicular cutaneous epithelial tumors. The specific nonfollicular tumors examined were squamous cell carcinoma, Bowen disease, actinic keratosis, eccrine porocarcinoma, and sebaceous carcinoma. Immunohistochemistry also was performed with a few anti-keratin monoclonal antibodies. As a general rule, K6 and K16 were expressed in hyperproliferative conditions, such as epidermal tumors, and K17 was coexpressed in the same lesions. The ratio of K16 to K17 in many epithelial skin tumors has been unclear until now. K17 content exceeded K16 content in most follicular tumors, whereas in almost all the nonfollicular tumors and the psoriatic epidermis, K17 levels were less than or about equal to K16 levels. There was a significant difference in the ratio of K16 to K17 between follicular and nonfollicular skin tumors. These results indicate that alterations in the content of these keratins may be associated with follicular differentiation.

An immunohistochemical study of sebaceous carcinoma with anti-keratin monoclonal antibodies: comparison with other skin cancers

Formalin-fixed and paraffin-embedded tissue specimens of six cases of extraocular sebaceous carcinoma were studied immunohistochemically with eight anti-keratin monoclonal antibodies, 34 beta B4, 35 beta H11, Ks13.1, Ks19.1, PKK1, LP34, KL1 and AE1. The staining patterns of sebaceous carcinoma were compared with those of normal sebaceous glands and other skin cancers which should be distinguished from sebaceous carcinoma histopathologically. The other skin cancers compared were eccrine porocarcinoma, malignant clear cell hidradenoma, extramammary Paget's disease with underlying adenocarcinoma, malignant trichilemmoma, and squamous cell carcinoma. Most cases of sebaceous carcinoma were stained with 35 beta H11, Ks19.1, LP34, KL1 and AE1, while normal sebaceous glands were positive only with 35 beta H11, LP34, KL1 and AE1. By immunostaining, sebaceous carcinoma was distinguishable from extramammary Paget's disease with underlying adenocarcinoma, squamous cell carcinoma, malignant trichilemmoma, and eccrine porocarcinoma, but was not clearly distinguishable from malignant clear cell hidradenoma. These findings demonstrate that sebaceous carcinoma shows positive reactions with antibodies to simple epithelial keratin, probably as a result of neoplastic transformation, and that immunohistochemical examination using anti-keratin monoclonal antibodies is useful in distinguishing sebaceous carcinoma from several other skin cancers.

bcl-2 expression reliably distinguishes trichoepitheliomas from basal cell carcinomas

Trichoepitheliomas (TE) are benign follicular neoplasms which are frequently confused with basal cell carcinomas (BCC). It is important to distinguish these entities precisely, as the treatments and prognoses are different. To this end, we stained a series of formalin-fixed, paraffin-embedded specimens of unequivocal TE and BCC with antibodies directed against bcl-2, an oncogene associated with programmed cell death, and known to be overexpressed in some malignant tumours. The TE showed staining of tumour cells limited to the outermost layer of the proliferation. The BCC tumour cells demonstrated diffuse staining throughout the tumour nodules. This difference in staining pattern was then applied to more equivocal cases, and seemed clearly to separate the entities. The observed findings may prove to be of diagnostic help in distinguishing borderline cases, and also offer some possible explanations for the biological differences between these neoplasms.