Clonal nature of seborrheic keratosis demonstrated by using the polymorphism of the human androgen receptor locus as a marker

Relationship between α-genus human papillomavirus and non-genital seborrheic keratosis: Report of new cases and updated review

BACKGROUND

Seborrheic keratoses (SK) are the most common acquired benign tumor that affects middle-aged or older adults with great cosmetic concern. Clinical and histopathological similarities of SK and common warts have been addressed by investigating the possible presence of human papillomavirus (HPV) DNA in SK. Previous studies suggested the association between α-genus HPV and SK located on genital skin, whereas the causal relationship between α-HPV and non-genital SK remains controversial.

AIM

This study aimed to clarify the pathogenic involvement of α-HPV in the development of non-genital SK.

METHODS

We analyzed α-HPV DNA prevalence and HPV genotypes using a PCR-based microarray on 51 skin samples presenting with histologically confirmed SK without any malignant changes. Correlation between the histological subtype of SK and their HPV DNA-positive reactivity was also evaluated.

RESULTS

Of 51 non-genital SK, two (3.9%) skin samples were positive for α-HPV DNA; high-risk HPV 31 and low-risk HPV 42 were found. Evaluation of HPV prevalence in different histological types of SK showed that both HPV-positive cases were acanthotic type; 14.3% of acanthotic SK lesions were positive, while all of the other types were negative for α-HPV.

CONCLUSIONS

This study demonstrates that α-HPV positivity is very rare in common non-genital SK. The rare α-HPV-positive SK lesions histologically belonged to the acanthotic type, implying a potential impact of HPV infection on epidermal hyperproliferation. Although a possible association cannot be excluded, our findings suggest that α-HPV is not a major causative factor for non-genital SK.

Clonal-pattern Seborrheic Keratosis: Risk of Recurrence and Progression to Carcinoma

Seborrheic keratosis is a benign epidermal tumor. Seborrheic keratosis with clonal pattern (CPSK) displays histologic features distinct from other subtypes of SK (non-CPSK). We sought to quantitatively assess the risk of recurrence and progression to squamous cell carcinoma (SCC), either in situ or invasive, of incompletely excised CPSKs. We studied all 244 cases from 238 patients of "seborrheic keratosis, clonal pattern" diagnosed in our institution over a 10-year period (2008-2018). Demographic, clinical, pathologic, and follow-up data were gleaned from electronic health records. Following glass slide review, CPSK lesions were divided into 2 groups: CPSK with cytologic atypia and CPSK without cytologic atypia. For comparison, 107 non-CPSKs were studied as controls. The minimum follow-up period was 2 years (median=4 y). All lesions were incompletely excised. Eighteen of 244 CPSKs (7.4%) recurred at or adjacent to the site of initial partial removal compared with 1.9% of non-CPSKs. Five of the 18 (28%) recurrent CPSKs recurred as CPSK, 11 (61%) as SCC in situ, and 3 (17%) as invasive SCC. The mean time to recurrence was 3.1 years. Two non-CPSKs recurred as non-CPSKs. Overall CPSKs were more likely to recur than non-CPSKs ( P =0.04). CPSKs with atypia were more likely to recur than CPSKs without atypia ( P =0.03). The upgrade rate to SCC at least in situ of all recurrent CPSK lesions with atypia was 78%. Our results suggest that pathologists should report the presence of clonal pattern when observed in seborrheic keratoses, indicate the presence of atypia, and provide lesional margin assessment.

Seborrheic Keratosis With Sebaceous Differentiation, a Series of 8 Cases and Critical Review of the Literature

ABSTRACT

Seborrheic keratosis with sebaceous differentiation (SKSD) can sometimes raise uncertainty, confuse with other even malignant entities, and lead to overestimation of this harmless variant. Retrospective analysis of the cases diagnosed as SKSD and a search of the pertaining literature were conducted. Eight cases of SKSD were found. Histologically, these lesions show a flat to plate-like outgrowth of basaloid cells with solitary or clustered sebocytes at the bottom of the rete ridges and variable sebaceous ducts with luminal cuticula. The lesions differed in the outgrowth subpattern: flat/macular, acanthotic, or reticulated. No association was found with Muir-Torre syndrome, and no malignant transformation was seen in these lesions. Literature search revealed confusingly designated lesions that simply represented SKSD. SKSD can show several growth patterns as classic SK. This entity is either underreported or even underrecognized. This entity is benign; however, according to the literature, exclusion of an associating Muir-Torre syndrome should be warranted. The published literature about this lesion is confusing and inconsistent. We suggest the avoidance of confusing terminology and particularly the terminus epithelioma for such lesions.

Usefulness of Dermoscopy to Provide Accurate Assessment of Skin Cancers

Seborrheic keratosis (SK) is the most common benign tumour of epidermal origin. In most cases, it is simple to recognize in the clinical examination. However, sometimes SK can be a problematic lesion. We present the cases of two patients with seborrheic keratosis in whom we diagnosed the skin cancer through dermoscopic and histopathological examinations. The article aims to draw attention to the need for dermoscopic examinations to be included for an accurate assessment of the nevi not only by dermatologists but also not-specialized doctors. We would like to underline that many skin cancers share the similar features of malignancy, and competence and capability to interpret the dermoscopic pictures correctly are important for early recognition of malignant lesion. Very often malignant skin cancers can be hidden among benign lesions like seborrheic keratosis or they can be imitators of benign lesions. Amongst all cases of imposing SK, basal cell carcinoma, squamous cell carcinoma, melanoma is the most important differential diagnosis, of which their dermoscopic features will be discussed in this article.

Comparative evaluation of topical diclofenac sodium versus topical ibuprofen in the treatment of seborrheic keratosis

In 2016, a case of seborrheic keratosis was successfully treated with diclofenac gel 3%. Diclofenac gel mechanism of action is most likely through induction of apoptosis. This study included 30 patients with multiple seborrheic keratosis. One lesion was treated with topical diclofenac sodium gel 1% and another lesion with topical ibuprofen gel applied twice daily for 8 weeks. Adobe photoshop CS6 was used to measure the surface area of the lesions before treatment and after 8 weeks. There was a highly statistically significant difference in the surface area of the lesions before and after treatment with topical diclofenac 1% gel (P = .001) but there was no statistically significant difference with topical ibuprofen gel (P = .057). There was a highly significant difference between the two treatment regimens as regard the percentage of change in surface area of the lesions, with higher change in the diclofenc 1% gel-treated group (P = .001). No patients complain from any side effect from either treatment.

A challenging case of pigmented Bowen's disease and differential diagnosis of pagetoid pigmented skin lesions

Differentiation of pagetoid cutaneous neoplasms can be very challenging on hematoxylin and eosin-stained sections.

We report a singular case of pigmented pagetoid Bowen’s disease showing transitional features between extramammary Paget’s disease and in situ squamous cell carcinoma.

Dermatologic Problems Commonly Seen by the Allergist/Immunologist

Allergists/immunologists see a variety of skin disorders, some of which have a known immunologic basis whereas others do not. We review the prevalence, etiology, clinical presentation, and effective and low-cost care of common dermatologic conditions seen in outpatient practices. Conditions discussed include pityriasis alba, seborrheic dermatitis, rosacea, acne, tinea infections, intertrigo, lichen planus, tinea versicolor, lichen simplex chronicus, scabies, pityriasis rosea, keratosis pilaris, and seborrheic keratosis. An understanding of frequently encountered cutaneous diseases and their therapies will help provide immediate access to treatment and improve the experience for both the affected patient and the clinician.

Genetic alterations in seborrheic keratoses

Seborrheic keratoses are common benign epidermal lesions that are associated with increased age and sun-exposure. Those lesions despite harboring multiple somatic alterations in contrast to malignant tumors appear to be genetically stable. In order to investigate and characterize the presence of recurrent mutations, we performed exome sequencing on DNA from one seborrheic keratosis lesion and corresponding blood cells from the same patients with follow up investigation of alterations identified by exome sequencing in 24 additional lesions from as many patients. In addition we investigated alterations in all lesions at specific genes loci that included FGFR3, PIK3CA, HRAS, BRAF, CDKN2A and TERT and DHPH3 promoters. The exome sequencing data indicated three mutations per Mb of the targeted sequence. The mutational pattern depicted typical UV signature with majority of alterations being C>T and CC>TT base changes at dipyrimidinic sites. The FGFR3 mutations were the most frequent, detected in 12 of 25 (48%) lesions, followed by the PIK3CA (32%), TERT promoter (24%) and DPH3 promoter mutations (24%). TERT promoter mutations associated with increased age and were present mainly in the lesions excised from head and neck. Three lesions also carried alterations in CDKN2A. FGFR3, TERT and DPH3 expression did not correlate with mutations in the respective genes and promoters; however, increased FGFR3 transcript levels were associated with increased FOXN1 levels, a suggested positive feedback loop that stalls malignant progression. Thus, in this study we report overall mutation rate through exome sequencing and show the most frequent mutations seborrheic keratosis.

Sustained Akt Activity Is Required to Maintain Cell Viability in Seborrheic Keratosis, a Benign Epithelial Tumor

Seborrheic keratoses (SKs) are common benign skin tumors that share many morphological features with their malignant counterpart, squamous cell carcinoma. SKs frequently have acquired oncogenic mutations in the receptor tyrosine kinase/phosphatidylinositol 3-kinase/Akt signaling cascade. We developed a reliable culture system to study SKs in vitro and screened these cells using a library of selective kinase inhibitors to evaluate effects on cell survival. These benign tumors are sensitive to inhibition by ATP-competitive Akt inhibitors, including A-443654 and GSK690693. RNA interference-mediated Akt suppression mimicked the effects of enzyme inhibition in cultured cells. Akt inhibition suppressed phosphorylation of downstream targets of Akt kinase that are critical for cell survival, including MDM2 and FOXO3a, and induced apoptosis. Cell death was also dependent on p53, mutations in which, although common in cutaneous squamous cell carcinoma, have not been identified in SKs. Intact explants of SKs were also sensitive to Akt inhibition. In addition to the obvious therapeutic implications of these findings, identifying the signaling characteristics that differentiate benign and malignant tumors may inform our understanding of the malignant state.

Melanoacanthoma of external ear: report of two cases

Melanoacanthoma is a rare lesion. Melanoacanthoma of external ear is still rarer. We present two cases of melanoacanthoma of external ear in adults which presented as pigmented growths and clinically were suspected as malignant lesions. Histopathology was diagnostic as it demonstrated the characteristic elevated lesion with abundant melanin pigment. No recurrence of the lesion was reported after four years of initial diagnosis. These cases have been presented because of their uncommon location, highlighting the differential diagnoses.

Microarray analysis reveals increased expression of ΔNp63α in seborrhoeic keratosis

BACKGROUND

Seborrhoeic keratoses (SKs) are very common benign epidermal lesions without malignant potential. Ultraviolet radiation, old age and viruses are well-known risk factors for disease development. However, the pathomechanisms of SK are not fully understood.

OBJECTIVES

To detect and characterize the genes that are involved in the pathogenesis of SK.

METHODS

We performed a gene expression study using paired lesional and nonlesional skin samples from patients with SK.

RESULTS

We identified and validated 19 differentially expressed genes in SK. Of these 19 genes, we focused on p63 transcription factor, which plays a pivotal role in epidermal development by regulating its transcriptional programme. We found by immunofluorescence that the expression of ΔNp63α, the most abundantly expressed p63 isoform, was significantly increased in SK as compared with normal skin. Moreover, siRNA-mediated knockdown of ΔNp63 led to the downregulation of 11 genes, including a member of the tensin family TNS4. Chromatin immunoprecipitation assay revealed that TNS4 was a target gene of p63.

CONCLUSIONS

We identified upregulated genes in SK using genome-wide cDNA microarray and elucidated the functional contribution of p63 to the disease transcriptome by gene-silencing assay. Taken together, these data may provide a novel insight into the molecular basis of these benign skin lesions.

Multiple oncogenic mutations and clonal relationship in spatially distinct benign human epidermal tumors

Malignant tumors result from the accumulation of genetic alterations in oncogenes and tumor suppressor genes. Much less is known about the genetic changes in benign tumors. Seborrheic keratoses (SK) are very frequent benign human epidermal tumors without malignant potential. We performed a comprehensive mutational screen of genes in the FGFR3-RAS-MAPK and phosphoinositide 3-kinase (PI3K)-AKT pathways from 175 SK, including multiple lesions from each patient. SK commonly harbored multiple bona fide oncogenic mutations in FGFR3, PIK3CA, KRAS, HRAS, EGFR, and AKT1 oncogenes but not in tumor suppressor genes TSC1 and PTEN. Despite the occurrence of oncogenic mutations and the evidence for downstream ERK/MAPK and PI3K pathway signaling, we did not find induction of senescence or a DNA damage response. Array comparative genomic hybridization (aCGH) analysis revealed that SK are genetically stable. The pattern of oncogenic mutations and X chromosome inactivation departs significantly from randomness and indicates that spatially independent lesions from a given patient share a clonal relationship. Our findings show that multiple oncogenic mutations in the major signaling pathways involved in cancer are not sufficient to drive malignant tumor progression. Furthermore, our data provide clues on the origin and spread of oncogenic mutations in tissues, suggesting that apparently independent (multicentric) adult benign tumors may have a clonal origin.

A positive FGFR3/FOXN1 feedback loop underlies benign skin keratosis versus squamous cell carcinoma formation in humans

Seborrheic keratoses (SKs) are common, benign epithelial tumors of the skin that do not, or very rarely, progress into malignancy, for reasons that are not understood. We investigated this by gene expression profiling of human SKs and cutaneous squamous cell carcinomas (SCCs) and found that several genes previously connected with keratinocyte tumor development were similarly modulated in SKs and SCCs, whereas the expression of others differed by only a few fold. In contrast, the tyrosine kinase receptor FGF receptor-3 (FGFR3) and the transcription factor forkhead box N1 (FOXN1) were highly expressed in SKs, and close to undetectable in SCCs. We also showed that increased FGFR3 activity was sufficient to induce FOXN1 expression, counteract the inhibitory effect of EGFR signaling on FOXN1 expression and differentiation, and induce differentiation in a FOXN1-dependent manner. Knockdown of FOXN1 expression in primary human keratinocytes cooperated with oncogenic RAS in the induction of SCC-like tumors, whereas increased FOXN1 expression triggered the SCC cells to shift to a benign SK-like tumor phenotype, which included increased FGFR3 expression. Thus,we have uncovered a positive regulatory loop between FGFR3 and FOXN1 that underlies a benign versus malignant skin tumor phenotype.

Are all seborrheic keratoses benign? Review of the typical lesion and its variants

BACKGROUND

Seborrheic keratosis (SK) is one of the more common benign epidermal neoplasms seen in adult and middle-aged patients.

OBJECTIVE

As little is written in the literature about the variants of SK, this article aims to categorize and discuss the different subtypes and their important associations.

METHODS

An in-depth literature search using OVID Medline and PubMed was conducted to classify the various subtypes of SK. Clinical variants were photographed and used to help document the subtypes. The pathology is described for each.

RESULTS

Six subtypes of SK were identified: dermatosis papulosa nigra, stucco keratosis, inverted follicular keratosis, large cell acanthoma, lichenoid keratosis, and flat seborrheic keratosis. Although the etiology and pathogenesis of SKs are still largely debatable, several underlying mechanisms and contributing factors have been identified. All subtypes represent benign lesions, and treatment is usually done for cosmetic reasons. Several of the subtypes may act as cutaneous markers for internal malignancy and should be monitored closely for any atypical changes.

CONCLUSION

Although all subtypes of SK are benign, their association with other malignant lesions and ability to serve as cutaneous markers of internal malignancy emphasize the importance of correctly identifying all variants.

Overexpression of p27KIP1 in seborrheic keratosis

BACKGROUND

The pathogenesis of seborrheic keratosis (SK) is not well understood. SKs are slow growing, but the details of cell cycle control in these lesions are not known. We hypothesized that cyclin-dependent kinase inhibitors would be strongly expressed in SKs and that the proliferation rate would be low.

OBJECTIVES

To quantify the expression of Ki67, p16(INK4a), p21(WAF1), and p27(KIP1 )in SK.

METHODS

We assessed acanthotic SKs (n=10) and irritated SKs (n=10) for Ki67, p16(INK4a), p21(WAF1), and p27(KIP1 )expression using immunohistochemistry.

RESULTS

For nonirritated acanthotic pattern SKs, the Ki67 index was 3.4% (range 0.6-6.5%), confirming a low proliferation rate. The p16(INK4A) index was 6.0% (range 0-16%), and the p21(WAF1) index was 4.8% (range 0-25%). p27(KIP1) was strongly and diffusely expressed in all SKs, with a labeling index of 78% (range 75-85%). The labeling indices were similar in irritated SK lesions with a slightly increased proliferation rate and corresponding decrease in p27(KIP1) expression.

CONCLUSIONS

We conclude that in SKs, strong expression of the cyclin-dependent kinase inhibitor p27(KIP1) appears to be a major mechanism controlling keratinocyte proliferation.

Oncogenic PIK3CA mutations occur in epidermal nevi and seborrheic keratoses with a characteristic mutation pattern

Activating mutations of the p110 alpha subunit of PI3K (PIK3CA) oncogene have been identified in a broad spectrum of malignant tumors. However, their role in benign or preneoplastic conditions is unknown. Activating FGF receptor 3 (FGFR3) mutations are common in benign skin lesions, either as embryonic mutations in epidermal nevi (EN) or as somatic mutations in seborrheic keratoses (SK). FGFR3 mutations are also common in low-grade malignant bladder tumors, where they often occur in association with PIK3CA mutations. Therefore, we examined exons 9 and 20 of PIK3CA and FGFR3 hotspot mutations in EN (n = 33) and SK (n = 62), two proliferative skin lesions lacking malignant potential. Nine of 33 (27%) EN harbored PIK3CA mutations; all cases showed the E545G substitution, which is uncommon in cancers. In EN, R248C was the only FGFR3 mutation identified. By contrast, 10 of 62 (16%) SK revealed the typical cancer-associated PIK3CA mutations E542K, E545K, and H1047R. The same lesions displayed a wide range of FGFR3 mutations. Corresponding unaffected tissue was available for four EN and two mutant SK: all control samples displayed a WT sequence, confirming the somatic nature of the mutations found in lesional tissue. Forty of 95 (42%) lesions showed at least one mutation in either gene. PIK3CA and FGFR3 mutations displayed an independent distribution; 5/95 lesions harbored mutations in both genes. Our findings suggest that, in addition to their role in cancer, oncogenic PIK3CA mutations contribute to the pathogenesis of skin tumors lacking malignant potential. The remarkable genotype-phenotype correlation as observed in this study points to a distinct etiopathogenesis of the mutations in keratinocytes occuring either during fetal development or in adult life.

Nodular Hyperplasia of the Bartholin Gland: A Clinicopathological Study of Two Cases, Including Detection of Clonality by HUMARA

The authors report two examples of nodular hyperplasia of the Bartholin gland. Each occurred in the vulva, close to the introitus of women aged 33 and 49 years, who presented with slightly painful lesions that were clinically thought to be cysts. Grossly, both masses exhibited a multilobular architecture, were elastic, were gray in color, and measured 4 cm and 3.2 cm in greatest dimension. On microscopic examination, the lesions looked similar and exhibited an increased number of secretory acini, with maintenance of the normal duct-acinar relationship--features compatible with nodular hyperplasia. Rare dilated ducts were observed, and intraluminal inspissated secretions were occasionally seen. In one case, there were a focal mild inflammatory infiltrate, squamous metaplasia of larger ducts, and rare ruptured ducts with extravasated stromal mucin. Clonality analysis performed in one case revealed a monoclonal pattern, suggesting that the lesion may be a neoplastic process rather than simple reactive hyperplasia.

Squamous Eddies in Irritated Seborrheic Keratosis

Seborrheic keratosis is related to the intraepidermal hair follicle in its morphogenesis. Squamous eddies in irritated seborrheic keratosis (ISK) are known to develop by focal maturation of basaloid cells, but the significance of squamous eddies is not understood. The purpose of this study was to elucidate the nature of squamous eddies in ISK. Serial sections of paraffin blocks of 20 cases of ISK were examined. We tracked each squamous eddy through the serial sections to observe the different shapes and positions of the same squamous eddy. In 4 cases, squamous eddies revealed hair shafts at their centers in different sections. In 14 cases, squamous eddies contained acrotrichial canals. In 13 cases, squamous eddies were connected to keratotic invaginations we thought to be follicular infundibula. Eighteen of the 20 cases of ISK showed at least 1 of the morphological features of intraepidermal hair follicle structures. We have found that the squamous eddies of ISK are anatomically related to acrotrichia.

Clonal nature of sclerosing polycystic adenosis of salivary glands demonstrated by using the polymorphism of the human androgen receptor (HUMARA) locus as a marker

Sclerosing polycystic adenosis (SPA) is a recently described, rare lesion of the salivary glands that bears a resemblance to epithelial proliferative lesions of the breast. The true nature of the lesion is unknown, but up to now it has been generally believed to represent a pseudoneoplastic sclerosing and inflammatory process. However, local recurrence developed in about one-third of the cases. Superimposed dysplastic changes ranging from low-grade dysplasia to carcinoma in situ were described in SPA. Although no metastases-related and/or disease-related patient deaths were documented, these clinical and histopathologic features raise the possibility that SPA might represent a neoplastic lesion. Polymorphism of the human androgen receptor locus is most frequently used to assess whether the pattern of X-chromosome inactivation is random or nonrandom, the latter strongly indicating clonality. In this study, the assay was applied to tissue from 12 examples of SPA. Three cases (males) were noninformative and 3 cases (females) could not be analyzed owing to poor quality of DNA, but all the remaining 6 lesions satisfied the criteria for monoclonality. We therefore conclude that the findings in the present study are further supporting evidence that SPA is a neoplasm, and not just a reactive process.

High frequency of FGFR3 mutations in adenoid seborrheic keratoses

FGFR3 germline mutations cause autosomal dominant skeletal disorders including achondroplasia, thanatophoric dysplasia, severe achondroplasia with developmental delay and acanthosis nigricans, and Crouzon syndrome. Somatic mutations of FGFR3 have been identified in bladder cancer, multiple myeloma, and other neoplasms. FGFR3 mutations have also been detected in 40% of seborrheic keratoses (SKs) of the hyperkeratotic and acanthotic subtype, which are very common benign skin tumors. Using a multiplex SNaPshot assay that covers 11 activating FGFR3 mutations, we investigated a series of 27 SKs of the adenoid subtype. Mutations were detected in 23 of 27 (85%) adenoid SKs. R248C mutations were the most frequent mutation type. In two SKs, the A393E mutation was found, which has not been described in acanthotic and hyperkeratotic SKs so far. Three adenoid SKs displayed two simultaneous FGFR3 mutations. Adenoid SKs seem to be characterized by a higher frequency of FGFR3 mutations than hyperkeratotic and acanthotic SKs. The mechanism for the high rate of somatic FGFR3 mutations in these benign skin tumors remains elusive, but UV light exposure may play a potential role, especially in the R248C mutations.

Unusual Hyperplasia of Anogenital Mammary-Like Glands

Anogenital mammary-like glands, although known to exist (as ectopic breast tissue) as early as 1872, have only recently been thoroughly studied and suggested to be the possible origin for various neoplastic (benign and malignant) and reactive conditions that show a striking homology with lesions in the breast. Reported herein is an unusual benign lesion involving anogenital mammary-like glands in the perineal area of a 41-year-old woman. The lesion is unique in that it does not fully fit into any of the previously recognized conditions affecting anogenital mammary-like glands nor has it an apparent well-defined mammary counterpart. Microscopically, at first glance the lesion appeared as a cluster of extended anogenital mammary-like glands of variable complexity and a lobular architecture, which probably resulted from a compact proliferation of closely situated ducts with small, round lumens (when cut transversally). When cut longitudinally, some of these tiny ducts appeared to bud from larger ductal structures, resembling so-called satellitosis in the breast and this gave a fibroadenomatous appearance to the areas. In addition, there were adenosis-like areas. This lesion extends the spectrum of changes seen in anogenital mammary-like glands.

Adenosis tumor of anogenital mammary-like glands: a case report and demonstration of clonality by HUMARA assay

In mammary pathology, adenosis tumor is defined as a clinically recognizable lesion that histologically primarily consists of adenosis, but also exhibits various combinations of diverse epithelial changes seen in other benign breast diseases. A lesion that occurred in the anogenital area of a 46-year-old woman and apparently arose in anogenital mammary-like glands is described and which, in our opinion, is best classified as adenosis tumor. A biopsy revealed a well-demarcated, unencapsulated lesion surrounded by compressed fibrous tissue forming a pseudocapsule. Several histological patterns within the same tumor mass were recognizable: sclerosing adenosis-like changes, variably sized microcysts and cysts, some with rare short papillary projections having hyalinized cores, rare tubular structures exhibiting epithelial features reminiscent of simple ductal hyperplasia, areas with oxyphilic (apocrine) metaplasia, and clear cell epithelial changes resembling mucinous metaplasia. Decapitation secretion was notable in many lumens. Rare lumens were filled with foamy macrophages. There were also focal clear cell changes of myoepithelial cells. The stroma was paucicellular and sclerotic in some foci and composed of myofibroblasts and myxoid in others. Calponin, actins, and p63 stained myoepithelial cells. The cells in the oxyphilic (apocrine) metaplasia areas stained for mitochondrial antigen and Bcl-2. Antibodies to progesterone and estrogen receptor stained approximately 50 and 20% of the epithelial cell population, respectively. Human androgen receptor gene analysis yielded a monoclonal pattern. As our case exhibited a number of patterns identical to those seen in diverse benign breast diseases, its classification as adenosis tumor seems justifiable. This cutaneous perianal lesion is indistinguishable microscopically from its mammary analogue and was clinically detectable.

Genetic mosaicism in basal cell carcinoma

Human basal cell cancer (BCC) shows unique growth characteristics, including a virtual inability to metastasize, absence of a precursor stage and lack of tumour progression. The clonal nature of BCC has long been a subject for debate because of the tumour growth pattern. Despite a morphologically multifocal appearance, genetic analysis and three-dimensional reconstructions of tumours have favoured a unicellular origin. We have utilized the X-chromosome inactivation assay in order to examine clonality in 13 cases of BCC. Four parts of each individual tumour plus isolated samples of stroma were analysed following laser-assisted microdissection. In 12/13 tumours, the epithelial component of the tumour showed a monoclonal pattern suggesting a unicellular origin. Surprisingly, one tumour showed evidence of being composed of at least two non-related monoclonal clones. This finding was supported by the analysis of the ptch and p53 gene. Clonality analysis of tumour stroma showed both mono- and polyclonal patterns. A prerequisite for this assay is that the extent of skewing is determined and compensated for in each case. Owing to the mosaic pattern of normal human epidermis, accurate coefficients are difficult to obtain; we, therefore, performed all analyses both with and without considering skewing. This study concludes that BCC are monoclonal neoplastic growths of epithelial cells, embedded in a connective tissue stroma at least in part of polyclonal origin. The study results show that what appears to be one tumour may occasionally constitute two or more independent tumours intermingled or adjacent to each other, possibly reflecting a local predisposition to malignant transformation.

Hemosiderotic fibrohistiocytic lipomatous lesion: clinical correlation with venous stasis

Hemosiderotic fibrohistiocytic lipomatous lesion (HFLL) is a recently proposed lipomatous entity. HFLL was originally suggested to be a benign reactive lesion arising due to an antecedent trauma. We report two patients with HFLL who also suffered from chronic vein insufficiency due to varicose involving deep veins of the low limbs. Both patients were middle-aged women with solitary, poorly circumscribed subcutaneous lesions on the lower extremities. Histopathological examination revealed typical features of HFLL. We think that the consistent clinical features such as advanced age, female sex predilection, and specific location along with distinctive histopathological features allow the suggestion that impaired blood circulation, to wit, venous stasis is involved in the pathogenesis of HFLL. We hypothesize that the proliferation of spindled fibroblastic and myofibroblastic cells and capillaries, erythrocyte extravasation, and hemosiderin deposition with lipomatous tissue of HFLL may simply represent an exaggerated tissue response to venous stasis in which elevated venous and capillary pressures, oxygen saturation, and edema stimulate the proliferation of the above mentioned elements and lead to erythrocyte extravasation. A similar histopathological pattern is seen in acroangiodermatitis of Mali and vascular transformation of lymph node sinuses, and these conditions are also associated with impaired blood circulation.

Activating mutations of the tyrosine kinase receptor FGFR3 are associated with benign skin tumors in mice and humans

Specific germline activating point mutations in the gene encoding the tyrosine kinase receptor FGFR3 (fibroblast growth factor receptor 3) result in autosomal dominant human skeletal dysplasias. The identification in multiple myeloma and in two epithelial cancers-bladder and cervical carcinomas-of somatic FGFR3 mutations identical to the germinal activating mutations found in skeletal dysplasias, together with functional studies, have suggested an oncogenic role for this receptor. Although acanthosis nigricans, a benign skin tumor, has been found in some syndromes associated with germinal activating mutations of FGFR3, the role of activated FGFR3 in the epidermis has never been investigated. Here, we targeted an activated receptor mutant (S249C FGFR3) to the basal cells of the epidermis of transgenic mice. Mice expressing the transgene developed benign epidermal tumors with no sign of malignancy. These skin lesions had features in common with acanthosis nigricans and other benign human skin tumors, including seborrheic keratosis, one of the most common benign epidermal tumors in humans. We therefore screened a series of 62 cases of seborrheic keratosis for FGFR3 mutations. A large proportion of these tumors (39%) harbored somatic activating FGFR3 mutations, identical to those associated with skeletal dysplasia syndromes and bladder and cervical neoplasms. Our findings directly implicate FGFR3 activation as a major cause of benign epidermal tumors in humans.

Proteomic analysis of melanoma-derived exosomes by two-dimensional polyacrylamide gel electrophoresis and mass spectrometry

Exosomes are 40-100 nm vesicles released by numerous cell types and are thought to have a variety of roles depending on their origin. Exosomes derived from antigen presenting cells have been shown to be capable of initiating immune responses in vivo and eradicating established tumours in murine models. Tumour-derived exosomes can be utilised as a source of tumour antigen for cross-priming to T-cells and are thus of interest for use in anti-tumour immunotherapy. Further exploration into the protein composition of exosomes may increase our understanding of their potential roles in vivo and this study has examined the proteome of exosomes purified from cell supernatants of the melanoma cell lines MeWo and SK-MEL-28. The vesicular nature and size (30-100 nm) of the purified exosomes was confirmed by electron microscopy and sucrose density gradient centrifugation. Western blotting demonstrated the absence of calnexin and cytochrome c, verifying the purity of the exosome preparations, as well as enrichment of MHC class I and the tumour-associated antigens Mart-1 and Mel-CAM. The two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) protein profiles of exosomes from the two cell lines were highly comparable and strikingly different from the profiles of the total cell lysates. Mass spectrometric sequencing identified proteins present in 49 protein spots in the exosome lysates. Several of these have been identified previously in exosomes but some are novel, including p120 catenin, radixin, and immunoglobulin superfamily member 8 (PGRL). Proteins present in whole-cell lysates that were significantly reduced or excluded from exosomes were also identified and included several mitochondrial and lysosomal proteins, again confirming the proposed endosomal origin of exosomes. This study presents a starting point for future more in-depth protein studies of tumour-derived exosomes which will aid the understanding of their biogenesis and targeting for use in anti-tumour immunotherapy protocols.

X chromosome inactivation-mediated cellular mosaicism for the study of the monoclonal origin and recurrence of mouse tumors: a review

X chromosome inactivation-mediated cellular mosaicism was applied to study the clonal nature of experimental and human tumors and to judge whether apparently recurrent tumors which appear after therapeutic treatment are truly due to recurrence or due to new induction of a second tumor. Results show that the majority of experimental and human tumors, including benign tumors, are monoclonal and that the majority of apparently recurrent tumors are due to true recurrence. A series of experimental studies on this topic are reviewed.

Hyperplasia versus adenoma in endocrine tissues: are they different?

The traditional view holds that hyperplasia of endocrine glands is secondary to oversecretion of a trophic hormone. However, in most cases, the mechanism underlying this growth is the spontaneous proliferation of benign neoplasias. Pathologists still depend on subtle morphological criteria to delineate and further classify these tumours. Owing to their variable architecture, a bewildering nomenclature has emerged for these tumours, exemplified by the many names applied to the goitrous thyroid gland: hyperplasia, adenomatous goitre, adenomatoid nodules, benign nodular thyroid disease, adenoma, etc. This article reviews the evidence suggesting that: (1) the varied types of benign neogeneration of endocrine tissue, the spectrum of which ranges from 'simple hyperplasia' to 'true adenoma', involve the same process; (2) even clonality of a growing lesion cannot distinguish hyperplasia from neoplasia; and (3) the basic processes in both cases are not different from those that cause benign tumours in other organs.

Ageing and photoageing of keratinocytes and melanocytes

An overview of keratinocyte and melanocyte function is provided. The processes of cutaneous ageing and photoageing are defined, and age-associated modulations in gene expression are described. The changes in keratinocytes and melanocytes that occur with skin ageing and photoageing and the characteristics of chronologically aged vs. photoaged skin are delineated. Mutations that are found in malignant and premalignant tumors of epidermal origin are described.