The use of immunohistochemistry in the differential diagnosis of common epithelial tumours of the skin

Follicular (Infundibular-Tricholemmal) Squamous Cell Carcinoma: A New WHO Entity. Clinicopathological Features in 103 Cases, Including Follow-Up and Implications for Patient Management

AIMS

Cutaneous follicular (infundibular-tricholemmal) squamous cell carcinoma (FSCC) is a new World Health Organization entity. We present the largest series of published cases, summarizing clinical data, diagnostic criteria, differential diagnosis, and implications for patient management.

METHODS

Cases were identified from 2004 to 2011. Inclusion criteria included discrete attachment(s) of the tumor to the overlying epidermis via follicular infundibula, tricholemmal keratinization, and cellular pleomorphism. Keratoacanthoma and lesions with adjacent bowenoid epidermal dysplasia were excluded.

RESULTS

One hundred three cases of FSCC identified. 48.5% demonstrated completely circumscript borders (in situ for practical purposes), 12.6% uncertain for invasion (overwhelmingly pushing borders), and only 38.8% as clearly invasive. Follicular mucin in acantholytic spaces within tumor epithelium was a distinctive finding in 57.2% of cases. Clinical data indicated predominance in elderly (median 78.5 years) men (70.4%), with preferential head and neck location (81.6%). Many were clinically suspected as squamous cell carcinoma (48.5%). However, a significant minority were clinically diagnosed as basal cell carcinoma (40.8%). This may reflect that FSCC commonly presented as a papule or nodule (51.3%). By contrast, keratoacanthoma was less frequently suggested (17.2%) and still fewer lesions were suspected to be actinic keratosis/Bowen's disease (13.6%). Follow-up in 82 cases (median 26.5 months, range 3-144) identified 5 (6.1%) local recurrences. There was no instance of metastasis in the subgroup of lesions with completely circumscript borders. Three of 45 (6.7%) patients, with follow-up, considered to have tumors with invasive pushing, and/or infiltrative borders developed lymph node metastases.

CONCLUSIONS

FSCC is identified as a common skin cancer, incorporating historical entities, such as infundibular carcinoma and tricholemmal carcinoma, with readily identifiable histologic features. Correct diagnosis has implications for patient management; a significant subgroup of lesions show completely circumscript borders that are considered in situ for practical purposes.

Immunohistochemical Analysis of Single-Stranded DNA Binding Protein 2 in Non-Melanoma Skin Cancers

Single-stranded DNA binding protein 2 (SSBP2) is a tumor suppressor candidate. In this study, the expression level and clinicopathological significance of SSBP2 in squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) were evaluated. We also identified biological pathways associated with a set of genes potentially related to SSBP2. Immunohistochemistry (IHC) was performed on 70 SCC and 146 BCC cases to assess SSBP2 expression semi-quantitatively. In addition, the associations between SSBP2 expression and clinicopathological characteristics were analyzed. Gene ontology (GO) enrichment analysis was performed using publicly available data and web-based bioinformatics tools. Compared with BCC, SCC had a significantly low SSBP2 expression (p < 0.001). In total, 12 (17.1%) of the 70 SCC cases and 30 (20.5%) of the 146 BCC cases showed low SSBP2 expression. Among SCC cases, ulceration (p = 0.005) and a deep level of invasion (p = 0.012) showed an association with low SSBP2 expression. Local recurrence was slightly more common in the SCC subgroup with low SSBP2 expression, although the difference was not significant (p = 0.058). Using GO enrichment analysis, we identified several biological functions performed by a set of 36 genes in SCC. SSBP2 evaluation using IHC can be helpful in the differential diagnosis of SCC and BCC. SSBP2 expression was associated with tumor invasiveness in SCC.

CD47 Expression in Non-Melanoma Skin Cancers and Its Clinicopathological Implications

CD47 is a cell surface molecule and regulates diverse cellular responses. CD47 is highly expressed in cancer cells and has potential as a therapeutic target and prognostic factor in cancer patients. The expression patterns of CD47 in basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and its precursor lesions, and its clinicopathological significance were investigated. CD47 expression was evaluated by immunohistochemistry in 152 cases of BCC and 71 cases of SCC. For comparison of CD47 expression, actinic keratosis (AK), squamous cell carcinoma in situ (SCCIS), keratoacanthoma (KA), and normal skin (NS) tissue were used. CD47 expression in BCC was significantly lower than that of SCC (p < 0.001). CD47 expression levels in SCC and KA were significantly higher than those of NS and AK (p < 0.05). High CD47 expression was significantly associated with the presence of ulceration (p = 0.005) and a deeper level of invasion (p = 0.011) in BCC. In addition, high CD47 expression was significantly associated with the presence of ulceration (p = 0.019) and larger tumor size (p = 0.004) in SCC. CD47 expression was associated with tumorigenesis and tumor progression in non-melanoma skin cancers.

Utility of Ber-EP4 and MOC-31 in Basaloid Skin Tumor Detection

Ber-EP4 has been the traditional immunostain used for the detection of basaloid skin tumors. Recently, MOC-31 has shown be superior to Ber-EP4 in the detection of basosquamous basal cell carcinoma (BCC) and many centers are now using both Ber-EP4 and MOC-31 antibodies together to detect these lesions. The objective of this study was to compare the utility of using both Ber-EP4 and MOC-31 immunostains in the detection of basaloid skin tumors and to better characterize the previously unknown staining properties of MOC-31 in cutaneous lesions. To do this, 76 basaloid skin tumors stained with both Ber-EP4 and MOC-31 were obtained. Diagnoses included basosquamous BCC, Merkel cell carcinoma, adenoid cystic carcinoma, microcystic adnexal carcinoma, sebaceous carcinoma, trichoepithelioma, trichoblastoma, sebaceous adenoma, sebaceoma, and follicular induction overlying dermatofibroma. The distribution and intensity of Ber-EP4 and MOC-31 staining in these lesions was scored. These scores were analyzed using a truth table, χ test, and Pearson correlation tests. The overall mean and SD of the scores were also obtained. Overall, we found Ber-EP4 and MOC-31 to be statistically equivalent immunostains for the diagnosis of basaloid skin tumors. We recommend the use of only one of these antibodies and favor MOC-31 for the detection of basaloid skin tumors. We also describe MOC-31 staining properties in different cutaneous lesions.

CD34 and BerEP4 Are Helpful to Distinguish Basaloid Tricholemmoma From Basal Cell Carcinoma

Tricholemmoma, a benign follicular neoplasm with outer root sheath differentiation, typically comprises clear or pale cells, and when multiple is pathognomic of Cowden's syndrome. The tumor is probably underrecognized and in basaloid examples can be difficult to distinguish from basal cell carcinoma (BCC). We studied 55 tricholemmomas (including 15 basaloid cases) and compared immunohistochemical profile with nodular BCC from our archives. Basaloid and non-basaloid tricholemmomas had similar staining characteristics. BerEP4 was focally positive (range 10%-20%) in only 3/39 (7.7%) tricholemmomas compared with widespread positivity in BCC (90.8%, 139 of 151 cases with ≥50% tumor area stained). CD34 was expressed, usually focally (median 20%, range 10%-90%), in 52/53 (98.1%) tricholemmomas and was negative in all 21 BCCs stained. EMA staining lacked sensitivity or specificity in differentiating tricholemmoma from BCC. Five or more Merkel cells were found in 7/17 (40.1%) tricholemmomas and 1/23 (4.3%) nodular BCCs studied. In summary, immunohistochemistry is helpful in distinction between tricholemmoma, including difficult basaloid examples (BerEP4 negative or focal, CD34 positive) compared with BCC (BerEP4 widespread in most cases, CD34 negative). The presence of 5 or more Merkel cells is a relatively specific but not a particularly sensitive discriminator.

Clinical and pathological study on mixed tumors of the skin

Mixed tumor of the skin (MTS) is a rare benign tumor of the sweat glands with a reported frequency of 0.01% to 0.098%. The objective of the study is to investigate clinicopathological and immunohistochemical features of mixed tumor of the skin.This was a retrospective study of 21 patients diagnosed with MTS at the Institute of Dermatology and Venereology of Sichuan Provincial People's Hospital from 1980 to 2016. Pathological sections of all cases were reread and the diagnosis was verified.There were 14 males (67%) and 7 females (33%). MTS affected the face. The lesions were skin-colored or lightly red, with no subjective symptoms in most cases. Histopathologically, the tumors consisted of epithelial and interstitial components. The epithelium was mainly composed of cubic or polygonal cells, which can be seen within the tubule-like structures with bilayer epithelium. The inner cells mainly expressed cytokeratin and other epithelial markers. The outer cells expressed epithelial and mesenchymal markers. The outer cells expressed S-100, P63, and glial fibrillary acidic protein. The tumors showed interstitial mucus-like and fibrosis changes, and some parts had cartilage-like changes.Pathological diagnosis is particularly important because the clinical symptoms of MTS lack specificity.

Differential diagnostic significance of epithelial and stromal CD10 expression in tumors of trichogenic origin

BACKGROUND AND OBJECTIVES

The histological differential diagnosis between benign trichogenic skin tumors and basal cell carcinoma may be challenging. We therefore set out to investigate whether expression of CD10, a cell surface protein with neutral endopeptidase activity, might be a suitable marker for the histological differential diagnosis of trichogenic skin tumors.

PATIENTS AND METHODS

We immunohistochemically analyzed 119 cases of benign trichogenic skin tumors and basal cell carcinoma. These included 28 nodular and 15 sclerosing basal cell carcinomas, 21 Pinkus tumors, 20 trichoblastomas, nine trichofolliculomas, eleven trichoepitheliomas, five desmoplastic trichoepitheliomas, and ten seborrheic keratoses.

RESULTS

The majority of nodular basal cell carcinomas expressed CD10 in tumor cells at the peripheral (22/28 [75 %]). On the other hand, trichoblastomas revealed peripheral CD10 expression in only 10 % (2/20) of cases, whereas 50 % showed central expression (10/20). Peripheral epithelial expression of CD10 was also found in Pinkus tumors (9/21 [42.9 %]) and trichoepithelioma (4/11 [36.4 %]). Desmoplastic trichoepithelioma showed no tumoral CD10 expression at all (0/5 [0 %]), while the majority of sclerosing basal cell carcinomas was positive for CD10 (13/15 [86.7 %]).

CONCLUSIONS

Our findings suggest that epithelial expression of CD10 - and not peritumoral stromal CD10 expression, as has been postulated - may well be of differential diagnostic significance. The pattern of distribution of CD10-positive neoplastic cells in particular can be useful in the diagnosis of trichogenic tumors.

PTEN Mediates Activation of Core Clock Protein BMAL1 and Accumulation of Epidermal Stem Cells

Tissue integrity requires constant maintenance of a quiescent, yet responsive, population of stem cells. In the skin, hair follicle stem cells (HFSCs) that reside within the bulge maintain tissue homeostasis in response to activating cues that occur with each new hair cycle or upon injury. We found that PTEN, a major regulator of the PI3K-AKT pathway, controlled HFSC number and size in the bulge and maintained genomically stable pluripotent cells. This regulatory function is central for HFSC quiescence, where PTEN-deficiency phenotype is in part regulated by BMAL1. Furthermore, PTEN ablation led to downregulation of BMI-1, a critical regulator of adult stem cell self-renewal, and elevated senescence, suggesting the presence of a protective system that prevents transformation. We found that short- and long-term PTEN depletion followed by activated BMAL1, a core clock protein, contributed to accumulation of HFSC.

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PTEN downregulation leads to the enrichment of stem cells in the niche

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PTEN activates core clock protein BMAL1

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BMAL1 plays a role in PTEN-associated stem cell accumulation via AKT

Histomorphological and Immunohistochemical Reappraisal of Cutaneous Adnexal Tumours: A Hospital Based Study

Background. Diagnosing adnexal tumours of the skin is a challenge due to their wide variety, infrequent occurrence in practice, and confusing morphological picture. Aims and Objectives. The present study aims to observe the spectrum of adnexal tumours at our institute and to evaluate them based on histomorphological, histochemical, and immunohistochemical methods either alone or in combination for proper identification and classification. Materials and Methods. A partly retrospective and partly prospective study was conducted on adnexal skin tumours over a period of 6 years. Relevant clinical profile was recorded. Histopathological examination was carried out and special stains were applied as and when required. Immunohistochemistry was performed where diagnosis with routine stains was not possible. Results. A total of 150 skin tumour biopsies were received. There were 87 keratotic tumours, 39 adnexal tumours, and 24 melanocytic tumours. Amongst the adnexal tumours, 51.3% eccrine, 30.8% follicular, and 17.9% sebaceous tumours were seen. In five cases, histological diagnosis was troublesome where immunohistochemistry helped in making final diagnosis. Limitations. The sample size is small. Conclusion. Histomorphology is confirmatory in majority of the adnexal tumours but few rare lesions that mimic internal malignancy require a panel of immunomarkers to rule out other possible differentials.

Basal cell carcinomas showing histological features generally associated with cutaneous adnexal neoplasms

Basal cell carcinoma (BCC) is the commonest malignant neoplasm in humans. Although a histopathological diagnosis of BCC is straightforward in the vast majority of cases, unusual histological variants can present a diagnostic challenge. A small proportion of BCCs show features which are generally associated with cutaneous adnexal neoplasms. Such changes may involve either the epithelium or the stroma and can mislead the pathologist particularly in small biopsies. Despite the growing evidence which speculate that BCC is a primitive follicular tumor, it is unusual to encounter tumors which actually show definitive signs of adnexal differentiation. This review aims to address this somewhat overlooked aspect of a very common tumor and offers practical guidance to distinguish them from adnexal neoplasms which they might mimic.

Desmoplastic trichilemmoma of the facial region mimicking invasive carcinoma

Trichilemmoma is a hamartomatous proliferation arising from cells of hair follicle. Its desmoplastic variant simulates an invasive carcinoma. In this tumor, the cell of origin seems to be located in the superficial level of the hair follicle just below the basement membrane at the sebaceous gland level. We present a similar case which presented with an asymptomatic nodular lesion in the region above the upper lip on left side. Fine needle aspiration cytology raised the cytological possibility of a malignancy for which the lesion was excised. On histopathology the lesion was diagnosed as desmoplastic trichilemmoma. The case highlights the difficulty encountered in differentiating a benign adnexal tumor from malignant lesion based on cytology alone. Moreover, the extensive desmoplasia on histopathology raises the suspicion of invasive malignancy which requires to be carefully excluded. The superficial features of trichilemmoma and lack of cellular atypia is a useful diagnostic clue in such a situation. Positivity of CD34 can also be used to differentiate from basal cell carcinomas. The case reported here had a solitary lesion, but follow up is required for development of more lesions or multiple hamartomas in other organs as a part of Cowden's disease.

Primary cutaneous myxoid spindle cell squamous cell carcinoma: a clinicopathologic study and review of the literature

Mucocutaneous squamous cell carcinoma (SCC) may rarely exhibit intracellular mucin production. Extracellular mucin production is an even rarer finding in SCC that is not well documented in the literature. Here, we report six cases of primary cutaneous and mucocutaneous SCC with prominent extracellular stromal mucin deposition and an epithelial spindle cell component. We propose the term 'yxoid spindle cell SCC' (MSC SCC) to describe the histologic characteristics of these six cases. We also propose a set of histologic and immunohistochemical findings for distinguishing MSC SCC from primary cutaneous and metastatic spindle cell neoplasms including other sarcomatoid carcinomas, myxoid sarcomas and the spindle cell variant of atypical fibroxanthoma (AFX). The criteria can also help discern MSC SCC from spindle cell melanomas, which may rarely show a prominent myxoid stroma. Given the small numbers of cases reported to date, the presence of prominent myxoid stroma in primary cutaneous spindle cell SCC has unknown prognostic significance at this time.