Immunohistochemical Localization of Phosphorylated and Unphosphorylated Form of ß-catenin With Regard to Shadow Cell and Squamous Differentiation in Cutaneous Pilomatricoma.

Pilomatricoma usually contains a mutation in CTNNB1 that encodes ß-catenin (BC). It also shows nuclear accumulation of BC protein, which plays an important role in tumorigenesis of pilomatricoma. In vitro studies have indicated that mutant BC protein is unphosphorylated and shows nuclear accumulation, but this theory has not been confirmed in various tumors with CTNNB1 mutation. We examined immunohistochemical localization of phosphorylated BC (pBC) and unphosphorylated BC (npBC) with regard to the modes of cell death or differentiation in 25 cases of pilomatricoma. As for the component showing shadow cell differentiation, BC was detected in cytoplasm/nucleus and along cell membrane in basaloid cells, whereas only in the latter in transitional cells in all cases. Meanwhile, npBC was localized along cell membrane of transitional cells, but not in basaloid cells, nor in nucleus of any components. The components with squamous differentiation also revealed the staining patterns similar to those seen in shadow cell differentiation in some cases. pBC was found in some cell fragments in the amorphous debris containing apoptotic bodies among shadow cell nests. These results suggested that npBC plays an important role in cell adhesion during differentiation and that pBC expression is associated with apoptosis of basaloid cells in pilomatricoma. BC accumulated in the nucleus was not immunoreactive for npBC possibly due to post-translational modification or conformational changes that resulted in loss of or masked antigenicity when BC is assumed to be unphosphorylated.

Six cases of perforating pilomatricoma: Anetodermic changes with expression of matrix metalloproteinases.

Perforating pilomatricoma (PP) is a rare clinical variant of pilomatricoma presenting as a crusted or ulcerated nodule. Previous reports have suggested that the tumor cells perforate the epidermis through a process of transepithelial elimination. Here, we report six cases of PP and examine the mechanism of transepithelial elimination in PP. Histologically, the dermis above or around the tumor nest exhibited edema, dilated vascular spaces, sparse collagen bundles and absence of elastic fibers, suggesting anetodermic changes in all cases. Immunohistochemistry demonstrated many CD68-positive macrophages around the tumor nests. Matrix metallopeptidase (MMP)-9 and MMP-12 were expressed in the inflammatory cells and tumor cells, and were also present in the epidermis and fibroblasts in all cases. We speculate that in PP anetodermic change caused by MMP and elastases including MMP-9 and MMP-12 may precede elimination of the tumor.

Sarcomatoid pilomatrix carcinoma.

Pilomatrix (pilomatrical) carcinoma is a rare cutaneous adnexal tumor with matrical differentiation and recurrent and metastatic potential. Sarcomatoid pilomatrix carcinoma is a rare variant which shows a sarcomatoid component intermingling with the epithelial one. There are only 4 cases previously published. We present an additional case on the hand of a 78 year-old man which appeared as a 6 mm hyperkeratotic, focally ulcerated plaque. A shave biopsy demonstrated a dermal infiltrative neoplasm, composed of markedly atypical-appearing basaloid cells with focal necrotic/ghost cells, as well as an intimately associated population of atypical oval to spindle-shaped cells. Both the epithelial and the sarcomatoid components expressed cytokeratins (CKs) AE1/AE3, CK 5/6 and CAM 5.2, as well as beta-catenin and LEF-1. The tumor failed to express CK7, CK20, S100, thyroid transcription factor 1 (TTF1), CDX2, prostate-specific antigen (PSA) and CD34. The tumor was completely excised with Mohs surgery, and there has been no recurrence in the 8 months of follow-up to date.

Multiple pilomatrixomas in a survivor of WNT-activated medulloblastoma leading to the discovery of a germline APC mutation and the diagnosis of familial adenomatous polyposis.

Because children diagnosed with WNT-activated medulloblastoma have a 10-year overall survival rate of 95%, active long-term follow-up is critically important in reducing mortality from other causes. Here, we describe an 11-year-old adopted female who developed multiple pilomatrixomas 3 years after diagnosis of WNT-activated medulloblastoma, an unusual finding that prompted deeper clinical investigation. A heterozygous germline APC gene mutation was discovered, consistent with familial adenomatous polyposis. Screening endoscopy revealed numerous precancerous polyps that were excised. This case highlights the importance of long-term follow-up of pediatric cancer survivors, including attention to unexpected symptoms, which might unveil an underlying cancer predisposition syndrome.

Basal Cell Carcinoma With Matrical Differentiation: Clinicopathologic, Immunohistochemical, and Molecular Biological Study of 22 Cases.

Basal cell carcinoma (BCC) with matrical differentiation is a fairly rare neoplasm, with about 30 cases documented mainly as isolated case reports. We studied a series of this neoplasm, including cases with an atypical matrical component, a hitherto unreported feature. Lesions coded as BCC with matrical differentiation were reviewed; 22 cases were included. Immunohistochemical studies were performed using antibodies against BerEp4, ß-catenin, and epithelial membrane antigen (EMA). Molecular genetic studies using Ion AmpliSeq Cancer Hotspot Panel v2 by massively parallel sequencing on Ion Torrent PGM were performed in 2 cases with an atypical matrical component (1 was previously subjected to microdissection to sample the matrical and BCC areas separately). There were 13 male and 9 female patients, ranging in age from 41 to 89 years. Microscopically, all lesions manifested at least 2 components, a BCC area (follicular germinative differentiation) and areas with matrical differentiation. A BCC component dominated in 14 cases, whereas a matrical component dominated in 4 cases. Matrical differentiation was recognized as matrical/supramatrical cells (n=21), shadow cells (n=21), bright red trichohyaline granules (n=18), and blue-gray corneocytes (n=18). In 2 cases, matrical areas manifested cytologic atypia, and a third case exhibited an infiltrative growth pattern, with the tumor metastasizing to a lymph node. BerEP4 labeled the follicular germinative cells, whereas it was markedly reduced or negative in matrical areas. The reverse pattern was seen with ß-catenin. EMA was negative in BCC areas but stained a proportion of matrical/supramatrical cells. Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components. It is concluded that matrical differentiation in BCC in most cases occurs as multiple foci. Rare neoplasms manifest atypia in the matrical areas. Immunohistochemical analysis for BerEP4, EMA, and ß-catenin can be helpful in limited biopsy specimens. From a molecular biological prospective, BCC and matrical components appear to share some of the gene mutations but have differences in others, but this observation must be validated in a large series.

IL-8, IL-8RA (CXCR1) and IL-8RB (CXCR2) expression in pilomatricoma.

Pilomatricoma is a rare benign tumor of the hair follicle matrix cells, which associates during its evolution a foreign body-like inflammatory process. We have investigated three such tumors, two of them displaying a rather poor stroma, while the third was distinctive due to its stroma and large numbers of inflammatory cells infiltrating the tumor. The analysis of IL-8 (interleukin-8), CXCR1 (IL-8RA - IL-8 receptor alpha) and CXCR2 (IL-8RB - IL-8 receptor beta) expression showed that these molecules are present not only in many different types of inflammatory and endothelial cells, but also in several tumor basaloid, transitional and even few ghost cells. Taking into consideration the roles played by IL-8 and its two receptors, CXCR1 and CXCR2, this pattern of expression offers some insights on the potential roles of these molecules in tumor survival, cell proliferation and angiogenesis. Furthermore, given the expression of IL-1 (interleukin-1) and TNF (tumor necrosis factor) receptors by the tumor cells, IL-8 production by such cells might be under the control of these pro-inflammatory cytokines.

Expression of epidermal stem cell markers in skin and adnexal malignancies.

BACKGROUND: Epidermal stem cells are multipotent cells that maintain the skin epidermis. Potential markers for stem cells have been identified in mammalian skin from mouse experiments; however, it is unclear if stem cells also contribute to tumour formation in human skin. OBJECTIVES: To investigate the expression of potential stem cell markers, such as leucine-rich repeat-containing G protein-coupled receptor (Lgr) 5, Lgr6, leucine-rich repeats and immunoglobulin-like domain protein 1 (Lrig1) and cytokeratin 15 (CK15) in basal cell carcinomas and tumours of the skin appendages. METHODS: We tested 45 human basal cell carcinomas (BCCs), including superficial, nodular, adenoid, infiltrating and sclerosing types, and 38 human tumours of skin appendages, including 13 sebaceous adenomas and carcinomas, 20 eccrine sweat gland tumours and five pilomatricomas, for the expression of hair follicle stem cell markers such as Lgr5, Lrig1, CK15, ß-catenin and SRY (sex determining region Y)-box 9 (SOX9), and compared these findings with those of healthy age-matched human epidermis. RESULTS: We detected the expression of stem cell markers in all tumours tested. Regarding Lgr5, Lrig1, CK15 and SOX9, expression seemed to be lower in more aggressive tumour types, such as in the most advanced parts of infiltrating BCC, in sebaceous carcinoma and late-stage porocarcinoma, compared with less aggressive superficial or nodular BCC or early-stage porocarcinoma and sebaceous gland tumours. In aggressive, sclerosing BCC, Lrig1 and Lgr5 were downregulated but CK15, SOX9 and nuclear ß-catenin were upregulated. CONCLUSIONS: Expression of potential stem cell markers of the epidermis and hair follicles was observed in skin tumours of appendages and BCCs. However, during tumour progression, many of these markers seemed to be downregulated.

Ghost cells in pilomatrixoma, craniopharyngioma, and calcifying cystic odontogenic tumor: histological, immunohistochemical, and ultrastructural study.

BACKGROUND: Pilomatrixoma, craniopharyngioma, and calcifying cystic odontogenic tumor are the main entities presenting ghost cells as an important histological feature, in spite their quite different clinical presentation; it seems that they share a common pathway in the formation of these cells. The aim of this study is to examine and compare the characteristics of ghost and other cells that form these lesions. METHODS: Forty-three cases including 21 pilomatrixomas, 14 craniopharyngiomas, and eight calcifying cystic odontogenic tumors were evaluated by immunohistochemistry for cytokeratins, CD138, ß-catenin, D2-40, Glut-1, FAS, CD10 and also by scanning electron microscopy. RESULTS: The CKs, CD138, ß-catenin, Glut-1, FAS, and CD10 were more often expressed by transitional cells of craniopharyngioma and calcifying cystic odontogenic tumor, compared with pilomatrixoma. Basaloid cells of pilomatrixoma showed strong positivity for CD138 and CD10. Differences on expression pattern were identified in transitional and basal cells, as ghost cells were negative for most antibodies used, except by low expression for cytokeratins. By scanning electron microscopy, the morphology of ghost cells were similar in their fibrillar cytoplasm, but their pattern varied from sheets in pilomatrixoma to small clusters in craniopharyngioma and calcifying cystic odontogenic tumor. CONCLUSIONS: Mechanisms involved in formation of ghost cells are unknown, but probably they follow different pathways as protein expression in the basal/transitional cells was not uniform in the three tumors studied.

YAP immunoreactivity is directly related to pilomatrixoma size and proliferation rate.

Organ size regulation is a highly coordinated process involving complex mechanisms. Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif, also known as WWTR1 (TAZ) have recently been linked to organ size determination and cell proliferation. Pilomatrixoma (PM) is a benign tumor of the adnexal appendages with a certain degree of differentiation toward the matrix of the hair follicle. PM presents as a dermal nodule that usually ranges from 0.5 to 2 cm, rarely exceeding 3 cm. We recently observed a case of unusual "giant" (6.5 cm) PM. Our hypothesis was that YAP and TAZ could be related to PM growth. We analyzed YAP and TAZ immunohistochemical expression in the giant and in ten usual size PMs in relation with tumor size and proliferation rate. YAP nuclear expression was remarkably higher in the giant PM in comparison with usual size PMs and statistically correlated, in a direct manner, with size and proliferation rate of PMs. Contrariwise, TAZ nuclear expression seemed stochastic. Our findings suggest that YAP could play a role in PM growth.

TGF-ß1-dependent induction and nuclear translocation of FHL2 promotes keratin expression in pilomatricoma.

Pilomatricoma is a tumour derived from hair matrix cells, which shows progressive keratin expression. Tumorigenesis is frequently associated with activating mutations in ß-catenin gene inducing nuclear expression of ß-catenin protein. The present study analysed the role of transforming growth factor-ß1 (TGF-ß1) and four-and-a-half LIM domain protein 2 (FHL2) in pilomatricoma in synopsis with their expression patterns in human anagen hair. Human anagen hair showed TGF-ß1 and nuclear FHL2 expression in the outer root sheath layer separated from nuclear ß-catenin staining, which was observed in cells of matrix and inner root sheath layers. Correspondingly, 41 out of 50 pilomatricomas showed co-labelling of TGF-ß1 and nuclear FHL2 in tumour cells, which mostly lacked nuclear ß-catenin expression. Tumoural proliferation (ki67) was associated with nuclear ß-catenin staining but not with expression of nuclear FHL2. In early pilomatricomas, TGF-ß1 expression was observed in few peripheral tumour cells showing absent or faint nuclear FHL2 co-staining. TGF-ß1 expression extended in growing tumours going along with strong nuclear FHL2 co-labelling as well as progressive keratin 14 and keratin 1 expression. In vitro, cultured human keratinocytes showed weak to marked autocrine TGF-ß1 expression; in case of enhanced TGF-ß1 expression associated with keratin 10 staining. TGF-ß1-treatment of cultured human keratinocytes induced nuclear and cytoplasmatic FHL2 staining as well as keratin 14 staining. Accordingly, siRNA-mediated FHL2 knockdown of TGF-ß1-stimulated keratinocytes reduced keratin 14 staining. In conclusion, tumoural TGF-ß1 secretion seems to induce nuclear translocation of co-factor FHL2 mediating progressive keratin expression in pilomatricoma.

Multiple eruptive pilomatricomas in a 9-year-old boy with glioblastoma.

A 9-year-old male presented to our dermatology clinic with a recent history of developing numerous cutaneous pilomatricomas, and was subsequently discovered to have sustained a recurrence of his glioblastoma multiforme. Immunohistochemical staining of a representative pilomatricoma and his original brain tumor revealed upregulation and nuclear localization of beta-catenin, a sign associated with poor prognosis in glioblastoma. We hypothesize that the development of multiple pilomatricomas may have been a hallmark of this patient's tumor recurrence and provide support for a recent report of an association between multiple pilomatricomas and gliomatosis cerebri.

Pilomatrix carcinoma of the clitoris.

Pilomatrix carcinoma, a malignant counterpart of pilomatrixoma, is a rare skin neoplasm composed of basaloid and shadow cells that characterize differentiation toward the hair matrix. The authors present a case of pilomatrix carcinoma of the clitoris, a very unusual location not previously reported. Diagnostic criteria and differential diagnoses are discussed. Pilomatrix carcinoma should be differentiated from benign pilomatrixoma and other carcinomas with shadow cells, including basal cell carcinoma with matrical differentiation and metastases of visceral carcinomas with shadow cells.

Differentiation and apoptosis in pilomatrixoma.

We carried out a histopathologic study of pilomatrixoma, a benign skin tumor, and also examined apoptosis and hair differentiation with the aim to understand the presence of amorphous debris and cyst formation in the tumor. Among 16 cases of pilomatrixoma examined, 11 were at the early regressive stage and 5 were at the late regressive stage according to the classification by Kaddu et al. In the former cases, tumor nests were basically composed of basophilic, transitional, and shadow cells. Cyst formation was evident in all cases and squamoid epithelium was observed in 4 cases at the early regressive stage. Amorphous debris was found in all cases including those at the late regressive stage. Immunohistochemical analysis revealed positive reaction products for ß-catenin and Lef-1 in basophilic and transitional cells, although their distribution differed. Immunoreactivity for ß-catenin was observed in the lower transitional cells, whereas immunoreactivity for Lef-1 was also evident in the upper transitional cells. Positive reactions for hair keratins were found in the cytoplasm of transitional and shadow cells, but not in the amorphous debris. Examination by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method revealed positive reactions in transitional and some shadow cells. These results suggest that in pilomatrixoma, production of hair keratin and induction of apoptosis may occur at the same time, and that unlike the normal hair follicle irregular expression of ß-catenin and Lef-1 results in the appearance of amorphous debris and cyst formation.

Melanocytic matricoma with melanocytic atypia: report of a unique case and review of the literature.

Melanocytic matricoma is a rare cutaneous neoplasm of presumed anagen hair follicle origin with approximately 10 reported cases in the literature. Melanocytic matricomas are clinically and histopathologically distinct cutaneous nodular proliferations of matrical and supramatrical cells admixed with dendritic melanocytes, which typically occur in the sun-exposed areas of elderly patients. We report a new case with additional histopathologic features not previously described. An 82-year-old white man presented with an exophytic papule of the ear clinically suspicious for basal cell carcinoma. Histopathologic examination demonstrated a polypoid neoplasm consisting of an admixture of matrical and shadow cells with numerous interspersed dendritic and epithelioid melanocytes arranged singly and in large expansile nests. An unusual feature in this case included prominent melanocytic proliferation with associated nuclear atypia and increased mitotic activity. Although atypical and malignant melanocytic colonization has been reported in basal cell carcinomas and squamoproliferative lesions, to our knowledge, it has not been previously described in melanocytic matricomas. The biologic significance of atypical melanocytic proliferations within melanocytic matricomas is uncertain and requires further study of additional cases and long-term follow-up.

Comparative immunohistochemical analyses on the modes of cell death/keratinization in epidermal cyst, trichilemmal cyst, and pilomatricoma.

Keratinization is a kind of cell death called terminal differentiation and includes various patterns such as epidermal keratinization (EK), trichilemmal keratinization (TK), and shadow cell differentiation (SCD), whereas these have not been comparatively investigated from a standpoint of cell death. In the present study, surgically extirpated specimens of epidermal cyst, trichilemmal cyst, and pilomatricoma (10 cases in each) were subjected to immunohistochemistry for single-strand DNA (ssDNA), gamma-H2AX, cleaved caspase-3, cleaved lamin A, caspase-14, and CD138 to compare the modes of cell death and keratinization pattern. Transitional cells in pilomatricoma were immunoreactive, although not in whole part, for ssDNA and gamma-H2AX, and negative for cleaved caspase-3 and cleaved lamin A. Epidermal and trichilemmal cyst were negative for these 4 markers, except for ssDNA or cleaved lamin A in a small number of parakeratotic cells in a few cases. The keratinizing component showed caspase-14(+)/CD138(-) in epidermal cyst, caspase-14(-)/CD138(+) in trichilemmal cyst, and caspase-14(-)/CD138(-) in pilomatricoma. These results indicate that EK, TK, and SCD have a common property of apoptosis-like programmed cell death without caspase-3 activation or nuclear fragmentation. Meanwhile, they show different characteristics one another as follows: (A), DNA double-strand breaks occur in the transitional cells of SCD but not in EK/TK; and (B), EK, TK, and SCD can be distinguished by expression pattern of caspase-14 and CD138 in the keratinizing component.

Melanocytic matricoma. Report of a further case with clinicopathological and immunohistochemical findings, differential diagnosis and review of the literature.

Melanocytic matricoma is a rare recently described lesion. It usually presents as a pigmented, dark-papular, crusted lesion on sun-damaged skin of adult patients. Histopathologically, these lesions are characterized by well-circumscribed nodules composed of matrical and supramatrical cells with clustered shadow cells, and admixed pigmented dendritic melanocytes. It differs from matricomas and pilomatricomas by its lack of calcification, cyst formation, granulomas, and connections to the epidermis and other adnexal structures. The clinical differential diagnosis includes hemangioma, pigmented basal cell carcinoma, and melanoma. Melanocytic matricoma presumably is the representation of an epithelial-melanocytic interaction in the anagen phase of the hair cycle. An extensive search of the medical literature revealed 11 reports of benign melanocytic matricomas and 5 malignant counterparts. We report an additional case of melanocytic matricoma with discussion of clinicopathologic features and differential diagnosis.

Basal cell carcinoma and pilomatrixoma mirror human follicular embryogenesis as reflected by their differential expression patterns of SOX9 and ß-catenin.

BACKGROUND: The current classification schemes of adnexal tumours are predominantly based on morphological and immunophenotypical similarities to adult skin structures, whereas a link between the embryology of the skin and the histogenesis of adnexal tumours has been largely neglected. OBJECTIVE: To describe the expression patterns of two proteins with proven relevance for hair follicle homeostasis (SOX9 and ß-catenin) during human cutaneous embryogenesis and to compare the findings with their expression in basal cell carcinoma (BCC) and pilomatrixoma. METHODS: Immunohistochemical evaluation with monoclonal antibodies against SOX9 and ß-catenin was carried out in embryonic and adult human scalp skin, and BCC and pilomatrixoma samples. RESULTS: We found that the expression patterns of SOX9 and ß-catenin during human hair follicle embryogenesis mirror the patterns in BCC and pilomatrixoma in spatial distribution within the various follicular subcompartments. Beginning with the hair peg stage, nucleocytoplasmic immunoreactivity of ß-catenin is exclusively confined to the emerging matrix (comparable to pilomatrixoma), whereas SOX9 is restricted to the primordial outer root sheath (comparable to BCC). CONCLUSIONS: An appropriate immunophenotyping validated within the conceptual framework of cutaneous developmental biology allows a logical classification of adnexal neoplasms. Expanding this approach further has the potential to revise the current classification schemes so that not only BCC and pilomatrixoma but all adnexal tumours can be categorized logically.

Apocrine mixed tumor of the skin with a prominent pilomatricomal component.

Pilomatrical differentiation within an apocrine mixed tumor (AMT) when present is only focal and has not been reported to be extensive. We herein report an AMT with prominent pilomatrical differentiation. A 47-year-old male presented with a 0.7 cm lesion on the right eyebrow. Histologic sections revealed, underneath a neurofibroma, a well-circumscribed tumor composed of nodules of branching epithelial elements and occasional keratinous cysts within a myxoid and lipomatous stroma. The ductal structures appeared to be composed of two layers of basophilic cuboidal cells and exhibited decapitation secretion. In approximately 50% of the tumor, eosinophilic ghost/shadow cells associated with a foreign body giant cell reaction formed a nodule resembling a pilomatricoma. Focally, columns of matrical cells were seen giving rise to shadow cells. Cytokeratin (CK) 5/6 and CK14 labeled the epithelial component. CK7, CK19 and Ber-EP4 labeled the ductal structures. Carcinoembryonic antigen and epithelial membrane antigen highlighted the luminal surface. S100 stained the stromal cells within the myxoid matrix, adipocytes and spindle cells within the overlying neurofibroma. CK10 highlighted the corneocytes within the keratinous cysts. CK17 labeled the epithelial lining of the keratinous cyst. The presence of follicular and apocrine differentiation within our tumor reinforces the common embryologic derivation of these elements.

Pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge.

Pilomatricoma is believed to differentiate towards the hair matrix and hair cortex. To elucidate the origin of differentiation in pilomatricoma, we studied the expression of epithelial keratin (K) and filaggrin (filament aggregating protein) in pilomatricoma. An immunohistochemical study has been made of 53 cases of pilomatricoma using 10 monospecific anti-keratin antibodies and anti-filaggrin antibody. Basophilic cells, transitional cells and shadow cells did not react with epithelial keratins and filaggrin antibodies as well as hair matrix and hair cortex. Instead, infundibular-type epithelium was positive for K1, K10 and filaggrin. Epithelium showing trichilemmal keratinization was positive for K14 and K16. The hair bulge-like structure was positive for K19. The differentiation of pilomatricoma is diversified, and is heterogeneous in epithelial keratin and filaggrin expression. Our results for keratin and filaggrin expression suggested that pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge.