Skin tumors with matrical differentiation: lessons from hair keratins, beta-catenin and PHLDA-1 expression

Atypical Melanocytic Matricoma: A Case Report with Molecular Studies

ABSTRACT

Melanocytic matricoma is a rare benign pilar tumor characterized by matrical differentiation and interspersed dendritic melanocytes. It may show cellular atypia and brisk mitotic activity. Histological characterization of some lesions may be difficult. In addition, because the reported cases are few and have limited follow-up, there is insufficient experience to define outcome-based criteria for malignancy. Some cases of melanocytic matricoma with more prominent atypia have been reported as malignant, but their clinical behavior is uncertain. We present a melanocytic matricoma with interspersed benign dendritic melanocytes, but moderate basaloid atypia, focally brisk mitotic activity, and atypical mitoses. Despite the apparently good delimitation of this tumor, higher magnification revealed a slightly irregular border. However, overt malignant features such as necrosis, frank asymmetry, deep infiltration, and ulceration were not present. This tumor showed a complex aberrant genomic profile with multiple whole chromosomes or chromosomal arms, losses, and duplications. The tumor mutational burden was high. A loss-of-function alteration in CDKN2A and a loss-of-function mutation in TP53 were also present. This unexpected molecular profile contrasts with the relatively bland histology of the tumor and is in line with the difficulties in microscopic differential diagnosis between melanocytic matricoma and an indolent malignant pilomatrical tumor. We suggest that molecular studies and longer follow-up periods may help to further understand and more precisely categorize borderline pilomatrical tumors with melanocytic hyperplasia.

Genetics of adnexal tumors: An update

Cutaneous adnexal tumors form a vast heterogeneous group that include frequent entities that are mostly benign, as well as rare tumors that are occasionally malignant. In contrast to cutaneous tumors arising from the interfollicular epidermis that develop as a result of accumulation of UV-induced DNA damage (basal cell carcinoma, squamous cell carcinoma), the oncogenesis of adnexal tumors is related to a broad spectrum of genetic mechanisms (e.g., point mutation, fusion genes, viral integration, etc.). In this setting, specific and recurrent genetic alterations have been progressively reported, and these allow better classification of these entities. For certain of them, immunohistochemical tools are now available, enabling precise integrated histological and molecular diagnosis since certain entities are linked to well-defined alterations. In this context, we aim in this review to summarize the main molecular tools currently available for the classification of adnexal tumors.

Onychomatricoma: a clinicopathological, immunohistochemical, and molecular study of 10 cases highlighting recurrent RB1 deletion and the potential diagnostic value of LEF-1

AIMS

Onychomatricoma (OM), an uncommon benign fibroepithelial neoplasm of the nail unit, is sometimes diagnostically challenging for clinicians and pathologists. OM consistently expresses CD34, but no specific immunohistohemical markers or recurrent genetic alterations have been identified to date. Recent studies have suggested that Wnt signalling is a key molecular characteristic of OM.

METHODS AND RESULTS

Ten cases were analysed: four classical OM including two with pleomorphic cells; two superficial acral fibromyxoma-like variants of OM; three micropapilliferum variants of OM including one with pleomorphic cells; and one proliferating variant of OM. Immunohistochemically, the spindle cells were positive with CD34 (n = 10) and CD99 (n = 1), with focal reactivity for CD10 (n = 5). The epithelial component of the tumours expressed immunopositivity for LEF-1. Using array comparative genomic hybridization (aCGH), we demonstrated that all OM, including its variants that were tested (n = 8), harboured a few copy number alterations with losses of whole or part of chromosome 13 including the RB1 gene (n = 8) and chromosome 16 (n = 6).

CONCLUSION

We report a recurrent loss of RB1 (13q) as a possible driver molecular event in OM indicating a relationship between OM and other lesions of the spectrum of the so-called '13q/RB1' family of tumours. We did not identify a role for the Wnt/beta-catenin signalling pathway, as has been proposed in a recent study. LEF-1 could be a potential sensitive and specific marker of OM and should be used in the differential diagnosis between OM, superficial acral fibromyxoma, and the CD34-positive fibrosing family of tumours.

Malignant Melanocytic Matricoma: A Rare Skin Tumor That Can Clinically Mimic Melanoma

Malignant melanocytic matricoma (MMM) is an extremely rare skin malignant neoplasm composed of epithelial cells with matrical differentiation and dendritic melanocytes. We found only 11 cases reported in the literature to date according to the databases consulted (PubMed/Medline, Scopus, and Web of Science). Here, we report a case of MMM in an 86-year-old woman. A histological examination showed a dermal tumor with a deep infiltrative pattern, without an epidermal connection. On immunohistochemical staining, tumor cells were positive for cytokeratin AE1/AE3, p63, and beta-catenin (nuclear and cytoplasmic staining) and negative for HMB45, Melan-A, S-100 protein, and androgen receptor. Melanic antibodies highlighted scattered dendritic melanocytes in tumor sheets. The findings did not support the diagnosis of melanoma, poorly differentiated sebaceous carcinoma, and basal cell carcinoma, but supported the diagnosis of MMM.

Melanocytic Panfolliculoma: A Case Report of a Rare Benign Follicular Tumor

ABSTRACT

Panfolliculomas (PF) are rare, benign, follicular tumors that differentiate toward multiple components of the hair follicle, and several variants have been described. We present a case of a rare pigmented PF presenting on actinically damaged skin in an 83-year-old man, which was clinically concerning for malignancy. This tumor arose near an area of atypical squamous proliferation and has evidence of infundibular, outer root sheath, and matrical differentiation and foci of heavy melanin pigmentation and increased melanocytes. We propose the novel designation of "melanocytic PF," akin to melanocytic matricoma but with panfollicular differentiation.

Pilomatrical Acanthoma: An Extremely Rare Intraepidermal Variant of Pilomatricoma

ABSTRACT

Pilomatrical differentiation can be observed in a variety of benign and malignant tumors, with the most common prototype being pilomatricoma. Pilomatricoma often presents in the deep dermis or subcutis, and the sole involvement of epidermis is extremely rare. In our current case series, specimens from 5 patients were included with an average age of 68 years. All lesions presented as solitary verrucous or keratotic papules on the extremities, with 1 lesion having a prominent horn. All lesions have a variable mixture of basaloid matrical cells and shadow cells, and all lesions express β-catenin (strong nuclear and cytoplasmic), lymphoid enhancer-binding factor 1 within the matrical component, and pleckstrin homology-like domain family A member 1. The histomorphology and immunoprofile of all lesions are of pilomatrical differentiation, confined to the level of the epidermis. Based on these findings and analogous to the terminology used for other benign intraepidermal proliferations (hidroacanthoma simplex and epidermolytic acanthoma), we propose the term "pilomatrical acanthoma" for these rare lesions.

Giant Pilomatrical Tumor With Broad Epidermal Components: An Example of Histological Diversity and a Potential Diagnostic Pitfall of Tumors With Pilomatrical Differentiation

ABSTRACT

The diagnosis of pilomatricoma, the most common matrical tumor, is generally straightforward; however, it exhibits diverse histology associated with various morphological stages and several clinical variants, and matrical differentiation can occur in various neoplastic diseases. A 56-year-old man was admitted to our hospital to resect an 11.0-cm skin tumor on his right shoulder. Because of its large size and surface irregularities, including multiple erosions and ulcers, cutaneous malignancies were clinically suspected. Histologically, the tumor formed numerous nodules with marked matrical differentiation in the superficial to deep dermis. Although the tumor was macroscopically asymmetrical and irregular, each nodule was microscopically round-shaped and consisted of basaloid cells without marked atypia, atypical mitoses, or lymphovascular invasion. Immunohistochemically, the tumor cells were positive for beta-catenin, LEF-1, and PHLDA-1, consistent with their pilomatrical differentiation. We diagnosed the case as a giant pilomatrical tumor with uncertain malignant potential, considering its "contradictory" features, namely, the worrisome histoarchitecture, such as the asymmetrical silhouette, but bland-looking cytological appearance. Unlike typical pilomatrical tumors, this tumor contained numerous epidermal components with features similar to those of the dermal components, resulting in a unique macroscopic and histological appearance. Our case broadens the known histological diversity of pilomatrical tumors.

The expression patterns and prognostic significance of pleckstrin homology-like domain family A (PHLDA) in lung cancer and malignant mesothelioma

Background

Pleckstrin homology domain family A (PHLDA) genes play important roles in cancer cellular processes, including inhibiting Akt activation, repressing growth factor signaling, inhibiting the negative feedback of EGFR/ErbB2 signaling cells, and inducing apoptosis. However, the prognostic significance of PHLDA in non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MM) remains unclear. The present study investigates the associations between PHLDA expression patterns and their prognostic value in lung adenocarcinoma (LUAD) and MM.

Methods

We analyzed PHLDA family members at the genomic level in silico to explore their mRNA expression pattern and predictive significance in LUAD and MM. We then created a PHLDA–drug interaction network and a protein-protein interaction (PPI) network using different databases. Finally, we immunohistochemically assessed the protein expression of each PHLDA family member on tissue microarrays (TMAs) in both LUAD and MM cohorts with long-term follow-up.

Results

While PHLDA1 mRNA expression in both LUAD and MM was lower than that of normal tissue, PHLDA2 mRNA was significantly overexpressed in LUAD, and PHLDA3 mRNA was overexpressed in MM. In NSCLC, both low PHLDA1 mRNA expression and high PHLDA3 mRNA expression correlated with worse overall survival (OS) (P<0.01), whereas high PHLDA2 mRNA expression was associated with better OS (P<0.01). In MM, patients presenting high PHLDA1 and PHLDA2 mRNA expression had poor OS (P=0.01 and P<0.01, respectively). In addition, the PHLDA-drug interaction network indicated that several common drugs could potentially modulate PHLDA expression, and the PPI network suggested that PHLDA1 interacts with Notch family members, whereas PHLDA3 interacts with TP53. Our results also showed that the expression of PHLDA2 and PHLDA3 was significantly higher in LUAD and MM than that of PHLDA1 (P<0.05) and was associated with the risk of death. While patients with PHLDA2 >85.09 cells/mm² had a low risk of death (P=0.01) and a median survival time of 48 months, those with PHLDA3 <70.38 cells/mm² had a high risk of death (P=0.03) and a median survival time of 34 months.

Conclusions

We shed light on the role of the PHLDA family as promising predictive biomarkers and potential therapeutic targets in LUAD and MM.

Bowen disease with matrical differentiation: Report of an exceptional histopathologic presentation

Matrical differentiation is the distinctive feature of pilomatricoma and other purely matrical adnexal neoplasms; additionally, foci of matrical differentiation have been also described in hybrid cysts of Gardner syndrome, as well as in a wide variety of benign and malignant cutaneous tumors, including basal cell carcinoma. We report an exceptional case of Bowen disease exhibiting multiple foci of matrical differentiation, as confirmed by means of immunohistochemical studies. Several types of divergent, non-squamous differentiation have been exceptionally reported in cutaneous squamous cell carcinoma in situ (cSCCIS), including sebaceous, mucinous/glandular, poroid, tricholemmal, and neuroendocrine differentiation; matrical differentiation may be added to this list. Our findings further emphasize the undifferentiated nature of neoplastic cells in cSCCIS.

Chaperone mediated detection of small molecule target binding in cells

The ability to quantitatively measure a small molecule’s interactions with its protein target(s) is crucial for both mechanistic studies of signaling pathways and in drug discovery. However, current methods to achieve this have specific requirements that can limit their application or interpretation. Here we describe a complementary target-engagement method, HIPStA (Heat Shock Protein Inhibition Protein Stability Assay), a high-throughput method to assess small molecule binding to endogenous, unmodified target protein(s) in cells. The methodology relies on the change in protein turnover when chaperones, such as HSP90, are inhibited and the stabilization effect that drug-target binding has on this change. We use HIPStA to measure drug binding to three different classes of drug targets (receptor tyrosine kinases, nuclear hormone receptors, and cytoplasmic protein kinases), via quantitative fluorescence imaging. We further demonstrate its utility by pairing the method with quantitative mass spectrometry to identify previously unknown targets of a receptor tyrosine kinase inhibitor.

Quantitative profiling of small molecule-protein binding in cells can aid basic biochemical research and drug discovery. Here, the authors develop the Heat Shock Protein Inhibition Protein Stability Assay (HIPStA) as a high-throughput method to assess cellular target engagement and identify new drug targets.

Salivary ghost cell carcinoma: case report and proposal of a new entity

Various topographically heterogeneous, histologically related groups of basaloid tumours are characterized by ghost cell differentiation with associated CTNNB1 mutations and nuclear β-catenin expression. We describe the unique case of a malignant tumour with ghost cell differentiation in the floor of the mouth, in which clinical, radiological, histological, immunohistological and molecular data altogether strongly indicate classification as a new type of salivary gland carcinoma.

Integrative analysis of the lncRNA-associated ceRNA network reveals lncRNAs as potential prognostic biomarkers in human muscle-invasive bladder cancer

Background

Long noncoding RNAs (lncRNAs) play important roles in competing endogenous RNA (ceRNA) networks involved in the development and progression of various cancers, including muscle-invasive bladder cancer (MIBC).

Purpose

This study aims to construct the lncRNA-associated ceRNA network and identify lncRNA signatures correlated with the clinical features of MIBC tissue samples from The Cancer Genome Atlas (TGCA) database.

Methods

The differential expression profiles of MIBC associated lncRNAs, miRNAs and mRNAs were obtained from TCGA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to determine the principal functions of significantly dysregulated mRNAs. The dysregulated lncRNA-associated ceRNA network of MIBC was constructed based on the bioinformatics data, and the correlations between lncRNA expression and clinical features were analyzed using a weighted gene coexpression network analysis (WGCNA). Six cancer specific lncRNAs from the ceRNA network were randomly selected to detect their expression in 32 paired MIBC tissue samples and 5 bladder cancer cell lines using quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The ceRNA network was constructed with 30 lncRNAs, 13 miRNAs and 32 mRNAs. Seventeen lncRNAs in the ceRNA network correlated with certain clinical features, and only 1 lncRNA (MIR137HG) correlated with the overall survival (OS) of patients with MIBC (log-rank test P<0.05). GO and KEGG analyses revealed roles for the potential mRNA targets of MIR137HG in epithelial cell differentiation and the peroxisome proliferator-activated receptor (PPAR) and tumor necrosis factor (TNF) signaling pathways. The expression data from TCGA were highly consistent with the verification results of the MIBC tissue samples and bladder cancer cell lines.

Conclusion

These findings improve our understanding of the regulatory mechanism of the lncRNA-miRNA-mRNA ceRNA network and reveal potential lncRNAs as prognostic biomarkers of MIBC.

CDX2 and LEF-1 expression in pilomatrical tumors and their utility in the diagnosis of pilomatrical carcinoma

BACKGROUND

The Wnt signaling pathway has been implicated in the pathogenesis of pilomatrical tumors. Lymphoid enhancer-binding factor 1 (LEF-1) is a downstream component of this pathway, and Caudal-related homeobox transcription factor 2 (CDX2) has been postulated to regulate it, but little is known about expression of these transcription factors in pilomatrical tumors.

METHODS

Immunohistochemistry for CDX2, β-catenin, LEF-1, CK19, CK5, Special AT-rich sequence- binding protein 2 (SATB2), cadherin 17 and androgen receptor was performed on pilomatricomas (PMs) (N = 12), pilomatrical carcinomas (PMCAs) (N = 12) and non-pilomatrical cutaneous tumors (N = 18).

RESULTS

PMs and PMCAs were positive for CDX2 (9/12 PMs, sensitivity = 75%, specificity = 100%; 11/12 PMCAs, sensitivity = 92%, specificity = 100%; P < 0.01), β-catenin (12/12 PMs, sensitivity = 100%, specificity = 94%; 10/12 PMCAs, sensitivity = 83%, specificity = 94%; P < 0.01) and LEF-1 (12/12 PMs, sensitivity = 100%, specificity = 56%; 12/12 PMCAs, sensitivity = 100%, specificity = 56%; P < 0.01). CDX2 expression was commonly focal, within a discrete subpopulation of squamoid cells. The LEF-1 expression pattern was different and discernable between pilomatrical tumors (strong, diffuse) and non-pilomatrical tumors (weak, patchy).

CONCLUSION

This study reaffirms the importance of the Wnt signaling pathway in the tumorigenesis of pilomatrical tumors, and this introduces CDX2 as a possible regulator and marker of pilomatrical tumorigenesis. LEF-1 and CDX2 performed at least as well as β-catenin, if not better when taking into account expression pattern, as a diagnostic marker for PMCA, and should be considered in the workup of ambiguous primitive-appearing cutaneous tumors.

HOXC13 promotes proliferation of esophageal squamous cell carcinoma via repressing transcription of CASP3

Esophageal squamous cell carcinoma (ESCC), the dominant subtype of esophageal cancer, is one of the most common digestive tumors worldwide. In this study, we confirmed that HOXC13, a member of the homeobox HOXC gene family, was significantly upregulated in ESCC and its overexpression was associated with poorer clinical characteristics and worse prognosis. Moreover, knockdown of HOXC13 inhibited proliferation and induced apoptosis of ESCC through upregulating CASP3. ChIP analysis revealed that HOXC13 repressed transcription of CASP3 through directly targeting the promotor region of CASP3. We also found that miR‐503 downregulated HOXC13, by directly targeting its 3′UTR, and inhibited proliferation of ESCC. In conclusion, our study demonstrates that HOXC13, which is directly targeted by miR‐503, promotes proliferation and inhibits apoptosis of ESCC through repressing transcription of CASP3.

Melanocytic Matricoma With Consumption of the Epidermis: An Atypical Histologic Attribute or a Malignant Variant?

Melanocytic matricoma is a recently described cutaneous adnexal tumor composed of matrical and supramatrical cells admixed with pigmented dendritic melanocytes, thought to recapitulate the anagen bulb of the hair follicle. We report a case of a 75-year-old white man, which demonstrates consumption of the epidermis that is defined as thinning of the epidermis with attenuation of the basal and suprabasal layers and loss of the normal rete architecture in areas of direct contact with neoplastic cells. It has been associated with aggressive histologic features in melanoma and likely represents an early phase of ulceration due to attenuation. Epidermal consumption has not been previously reported in nonmelanocytic tumors and it is uncertain whether this atypical histologic feature represents a sign of malignant behavior in this rare tumor.

Malignant Melanocytic Matricoma: A Report of 2 Cases and Review of the Literature

BACKGROUND

To describe 2 cases of melanocytic matricoma with malignant histological features and systematically review previously reported cases of malignant melanocytic matricoma.

METHODS

Two cases of malignant melanocytic matricoma were identified from the practice of the authors. Additional 3 cases were identified in the literature. The clinical and pathological features of these 5 cases are described.

RESULTS

Malignant melanocytic matricoma occurs predominantly in sun-damaged skin of elderly individuals. The tumor is composed of atypical epithelial cells with brisk mitotic activity showing evidence of matrical keratinization and widespread positivity with beta-catenin. There is an admixed cytologically bland dendritic melanocytic component. To date, local recurrence has occurred in one case, but no cases of disseminated disease or death have been reported.

CONCLUSIONS

Recognition of this rare tumor and separation from a range of diagnostic mimics is important to ensure adequate treatment by local excision and to allow further cases to be identified to better define the biological potential of this lesion.

Nasal Basal Cell Carcinoma with Matrical Differentiation: Risk of Metastasis and Impact on Management

Basal cell carcinoma (BCC) is the most common type of skin cancer. Microscopically, BCC can be classified into indolent-growth and aggressive-growth subtypes. Additionally, uncommon variants have been described in the literature including adamantinoid, granular, clear cell, and BCC with matrical differentiation (BCCMD). If left untreated, BCC can invade locally causing significant tissue destruction while metastatic BCC is extremely rare. There have only been rare cases of BCCMD previously reported in the literature with none exhibiting metastasis. In this report, a 76 year old male patient presented to our center with a recurrent nasal lesion. He had been diagnosed with BCC at another institution about 8 years prior. He underwent a completion rhinectomy procedure, and on microscopic examination the tumor was diagnosed as BCCMD. In view of the uncommon pathology, a PET scan was ordered, which showed a left submandibular hypermetabolic lymph node with central areas of necrosis. A fine needle aspirate from the node confirmed metastasis, and the patient underwent subsequent neck dissection. In conclusion, we have presented a very rare case of a nasal BCCMD with regional metastasis. To the best of our knowledge, this constitutes the first reported case in the English literature. This might raise the possibility of a probable metastatic potential for this lesion and subsequently a more aggressive behavior. However, it is to be noted that this is a single case report and the affirmation of any metastatic potential would still need to be confirmed through additional future reports.

Широкое многообразие кератинов человека

А review presents systematic data about the diversity of human keratins. The results of numerous studies concerning the structure and functions of keratins, their distribution in various cells and tissues were summarized. The role of these proteins in the development of human hereditary diseases, as well as modern approaches in use keratins in immunohistochemistry and perspectives of their further studies are discussed.

Matrical Carcinoma With Melanocytic Proliferation and Prominent Squamoid Whorls

Matrical carcinoma (pilomatrix carcinoma) is a rare follicular low-grade malignancy with matrical differentiation. A pigmented variant with admixed dendritic melanocytes is exceedingly rare with only 7 cases reported in the literature. The diagnosis of malignancy can be difficult to establish. The authors report a case of a 79-year-old woman with a matrical carcinoma who presented with an ulcerated nodule on the posterior right leg, measuring 2.2 cm in greatest dimension. The excisional biopsy showed irregularly shaped dermal and subcutaneous nodules ranging in size from 0.1 to 0.5 cm. The nodules were composed of aggregates of large atypical basaloid cells, with multiple, sometimes atypical, mitoses, admixed with ghost cells, and central necrosis en masse. In addition, the neoplasm was characterized by focal marked melanocytic proliferation and multiple whorls of pink eosinophilic material reminiscent of keratin pearls (squamoid whorls). The basaloid cells were positive for beta-catenin both in the nuclei and the cytoplasm and negative for BerEp4. S100, Melan-A, and HMB45 highlighted the melanocytic dendritic cells. Pan-cytokeratin was negative in the ghost cells and focally positive in the squamoid whorls. Squamoid whorls seem to be a significant feature of matrical carcinoma.

[Basal cell carcinoma with matrical differentiation]

Basal cell carcinoma with matrical differentiation is a very rare variant of basal cell carcinoma. To our knowledge, less than 30 cases have been reported. This tumor is composed of basaloid lobules showing a differentiation toward the pilar matrix cells. Recently, it has been demonstrated that beta-catenin would interfer with physiopathogenesis of matrical tumors, in particular pilomatricomas, but also basal cell carcinomas with matrical differentiation. This is a new case, with immunohistochemical and molecular analysis of beta-catenin, in order to explain its histogenesis.

TGF-β1-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 β-catenin gene inducing nuclear expression of β-catenin protein. The present study analysed the role of transforming growth factor-β1 (TGF-β1) 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-β1 and nuclear FHL2 expression in the outer root sheath layer separated from nuclear β-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-β1 and nuclear FHL2 in tumour cells, which mostly lacked nuclear β-catenin expression. Tumoural proliferation (ki67) was associated with nuclear β-catenin staining but not with expression of nuclear FHL2. In early pilomatricomas, TGF-β1 expression was observed in few peripheral tumour cells showing absent or faint nuclear FHL2 co-staining. TGF-β1 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-β1 expression; in case of enhanced TGF-β1 expression associated with keratin 10 staining. TGF-β1-treatment of cultured human keratinocytes induced nuclear and cytoplasmatic FHL2 staining as well as keratin 14 staining. Accordingly, siRNA-mediated FHL2 knockdown of TGF-β1-stimulated keratinocytes reduced keratin 14 staining. In conclusion, tumoural TGF-β1 secretion seems to induce nuclear translocation of co-factor FHL2 mediating progressive keratin expression in pilomatricoma.