Mutant p53 oncogene expression in keratoacanthoma and squamous cell carcinoma

Identifying SCC Lesions Capable of Spontaneous Regression by Using Immunohistochemistry: A Systematic Review and Meta-Analysis

INTRODUCTION

Keratoacanthoma (KA) and squamous cell carcinoma (SCC) are two cutaneous conditions with morphological resemblance, which can complicate the diagnosis in some cases. Using immunohistochemistry staining of biomarkers could be beneficial in resolving this obstacle.

OBJECTIVES

We investigated a variety of biomarkers assessed in different studies in order to find the most important and helpful biomarkers for differentiation between SCC and lesions capable of spontaneous regression.

METHODS

MEDLINE via PubMed and Google Scholar database were used to identify relevant literature up to 15 June 2022. The aim of our analyses was to determine the capability of biomarkers to distinguish between SCC and lesions capable of spontaneous regression using calculated individual and pooled odds ratios (OR) and 95% confidence intervals (CI) and I2 tests.

RESULTS

Six potential biomarkers were CD10 with pooled OR= 0.006 (95% CI: 0.001-0.057) and I2=0%; COX-2 with pooled OR=0.089 (95% CI: 0.029-0.269) and I2=17.1%; elastic fibers with pooled OR= 6.69 (95% CI: 2.928-15.281) and I2=0%; IMP-3 with pooled OR=0.145 (95% CI: 0.021-1.001) and I2=44.5%; P53 with pooled OR=0.371 (95% CI: 0.188-0.733) and I2=55.9%; AT1R with OR=0.026 (95% CI: 0.006-0.107).

CONCLUSIONS

We suggest the utilization of the following IHC biomarkers for discrimination between lesions with spontaneous regression such as KA and SCC: CD10, COX-2, and elastic fibers.

Aberrant p16, p53 and Ki-67 immunohistochemistry staining patterns can distinguish solitary keratoacanthoma from cutaneous squamous cell carcinoma

Keratoacanthoma (KA) is widely considered a benign, usually self-resolving, neoplasm distinct from cutaneous squamous cell carcinoma (cSCC), while some consider KA to be indistinguishable from cSCC. Published studies indicate utility for p16, p53, Ki-67 immunostaining and elastic van Gieson (EVG) in the assessment of KA and cSCC. We compared clinical features and staining patterns for p16, p53, Ki-67 and EVG in fully excised KA, cSCC with KA-like features (cSCC-KAL) and other cSCC (cSCC-OTHER). Significant differences between KA, cSCC-KAL and cSCC-OTHER were found for head and neck location (20%, 86%, 84%), and duration <5 months (95%, 63%, 36%). KA shows both a mosaic pattern for p16 (>25-90% of neoplasm area) and peripheral graded pattern for p53 (up to 50% moderate and strong nuclear staining) in 92% compared with 0% of cSCC-KAL and 0% of cSCC-OTHER. In contrast, a highly aberrant pattern (usually null) for one or both p16 and p53, was present in 0% of KA, 83.8% of cSCC-KAL and 90.9% of cSCC-OTHER. Abnormal distribution of Ki-67 beyond the peripheral 1-3 cells was uncommon in KA (4.2%) and common in cSCC-KAL (67.6%) and cSCC-OTHER (88.4%). Moderate to striking entrapment of elastic and collagen fibres was present in the majority of KA (84%), cSCC-KAL (81%) and cSCC-OTHER (65%). KA are clinically distinct neoplasms typically of short duration occurring preferentially outside the head and neck and generally lacking aberrations of p16, p53 and Ki-67, compared with cSCC that have high rates of aberrant or highly aberrant p16, p53 and Ki-67, but EVG lacked specificity.

Keratoacanthoma (KA): An update and review

Keratoacanthoma (KA) is a common but underreported tumor of the skin. Two striking features of KA are its clinical behavior with spontaneous regression after rapid growth and its nosological position on the border between benignity and malignancy. We review current knowledge on the clinical, histopathological, and dermoscopic features of KA to ensure a proper diagnosis and describe its variants, including different types of multiple KAs. We highlight current concepts of KA ethiopathogenesis with special emphasis on the genetic background of multiple familial KA, the role of Wnt signaling pathway, and induction of KA by BRAF inhibitors and procedures of esthetic dermatology. Finally, treatment strategies are presented with surgical excision as a first option, followed by other modalities, including intralesional chemotherapy, topical and systemic agents, lasers, cryotherapy, and photodynamic therapy.

Primary Invasive Squamous Cell Carcinoma of the Nipple

Squamous cell carcinoma is one of the most common cutaneous cancers; however, primary squamous cell carcinoma of the nipple is extremely rare. Among the few reported cases, the majority have occurred in older women with rare cases seen in younger women and male patients. Our patient presented with an exophytic mass of the right nipple while pregnant. A superficial biopsy was reviewed at an outside institution and then at our institution and diagnosed as squamous papilloma and then as hyperkeratosis of the nipple, respectively. The subsequent excisional biopsy revealed multiple nests of tumor cells extending into the dermis with associated chronic inflammatory infiltrate, and the lesion was diagnosed as a primary invasive squamous cell carcinoma of the nipple. Following that, a wide local excision of the excision site and sampling of the regional lymph nodes were negative for carcinoma. Due to the rarity of this diagnosis, it is not known whether prognosis and response to therapy differ from cutaneous squamous cell carcinoma at other sites. Therefore, risk stratification and therapy have been based on those for cutaneous squamous cell carcinoma.

Keratoacanthoma and Keratoacanthoma-Like Squamous Cell Carcinoma: Similar Morphology but Different Pathogenesis

Differential diagnosis between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is difficult due to their similarities. The mechanisms that drive their distinct biological behavior are poorly understood. To investigate whether the assessment of microvessel density (MVD) could be helpful in KA and SCC differential diagnosis and to gain insight into the pathogenesis of KA-like neoplasms, we compared the density of CD105- and CD34-stained vessels in KAs and SCCs and their relation to the expression of the p53 oncoprotein and proliferation marker Ki67. This is an observational retrospective cohort study. Forty lesions with clinical appearance of KAs (29 KAs and 11 SCCs) entered the study. A biopsy was taken from each lesion at presentation and the natural clinical course was monitored for at least 1 month. Growing or minimally regressing lesions were submitted to complete surgical excision. The diagnoses were established on combined clinical, histological, and follow-up evaluations. The MVD and p53 or Ki67 expression in neoplastic cells were assessed through morphometry. The MVD did not show discriminating power between KAs and SCCs. The Ki67 proliferation rate was significantly higher in SCCs. Although neoangiogenesis (CD105-MVD) in KAs was associated with cell proliferation, in SCCs it was not. There was significant correlation between p53 expression and neoplasia size in SCCs but not in KAs. From our results, we may conclude that KA and SCC have similarities, as CD105- and CD34-MVD. However, the low Ki67 proliferation index and the positive correlation between Ki-67 index and neovascularization in KA suggest a dependence in neovascularization to grow in KA, pointing to involvement of distinct pathogenesis.

Immunohistochemical evaluation of p53 and Ki67 expression in skin epithelial tumors

BACKGROUND AND AIMS

The cellular mechanisms responsible for initiating or limiting the tumors including skin types are of great importance. The p53 is a tumor-inhibiting gene which is believed to be defective in many malignant situations. Ki67 is a non-histonic protein which is mainly interfere with the proliferation and has many controlling effects during the cell cycle. Because of their importance in skin tumor cell growth, this study aimed at evaluating the p53 and Ki67 expression in skin epithelial tumors by immunohistochemical method.

MATERIALS AND METHODS

In a descriptive setting, 50 biopsy samples (30 basal cell carcinomas (BCCs), 10 squamous cell carcinomas (SCCs), 8 keratoacanthomas (KAs), and 2 trichoepitheliomas (TEs)) were immunohistochemically evaluated for p53 and Ki67 expression during a 14-month period. The incidence and expression rate of these two variables were separately reported in each group of samples.

RESULTS

The expression rate of p53 was 67.77% for the BCCs, 50.20% for the SCCs, and null for the KAs. For both TEs, it was 50%. The expression rate of Ki67 was 57.33% for the BCCs, 47.70% for the SCCs, 37.5% for the KAs, and 0.0% for TEs. The incidence of P53+ cells was 100% and 90% in the BCC and SCC samples, respectively. The both TEs were positive in this regard. The incidence of Ki67+ cells was 100% for the BCC, SCC, and KA samples. The both TEs were negative in this regard.

CONCLUSION

This study showed that the incidence rate of p53- and Ki67-positive cells is very high in skin malignant epithelial tumors. The expression rate of these two variables is comparable with reports in the literature. Further studies with large sample size are recommended to be carried out for KA and TE samples.

Phenol peels as a novel therapeutic approach for actinic keratosis and Bowen disease: prospective pilot trial with assessment of clinical, histologic, and immunohistochemical correlations

BACKGROUND

Although chemical peels may be used for precancerous lesions, no histologic or immunohistochemical studies have been performed to validate clinical impressions and/or outcome.

OBJECTIVE

Our purpose was to investigate the efficacy and prognostic relevance of phenol peels in Japanese patients with actinic keratosis and Bowen disease using clinical and histologic criteria.

METHODS

A total of 46 patients were treated with phenol peels, and followed up for at least 1 year after treatment. Biopsy specimens were taken before and after treatment. Cases of complete response were classified by the number of treatment sessions. We evaluated parameters for epidermal thickness, proliferation, dysplasia, and apoptosis, and clinical characteristics to correlate phenol peels with assessments of efficacy, patient-selection criteria, and risk for transformation to cutaneous squamous cell carcinoma.

RESULTS

There were 39 (84.8%) patients with a complete response after one to 8 treatment sessions. Statistically, differences in clinical improvement with peels and the number of treatment sessions correlated with histology, personal history of skin cancer, tumor thickness, and cyclin A expression.

LIMITATIONS

This study was a prospective pilot trial. Blinded, placebo-controlled, randomized studies would be ideal.

CONCLUSION

We conclude that phenol peels are very effective for treating precancerous lesions of actinic keratosis and Bowen disease. In addition, our study clearly demonstrates that tumor thickness and cyclin A could be specific and useful markers as adjunctive diagnostic tools to predict the efficacy of phenol treatment of these lesions.

Diagnosis and Follow-Up of Keratoacanthoma-Like Lesions: Clinical-Histologic Study of 43 Cases

Background:

Keratoacanthoma (KA) is easily confused with squamous cell carcinoma (SCC) on a clinical or a histopathologic basis. However, KA undergoes spontaneous regression, whereas SCC does not.

Objective:

Our objective was to study the histopathologic features associated with clinical regression in KA-like lesions to support the therapeutic option.

Methods:

Forty-three biopsies of KA-like lesions were taken at patient admission. One month later, surgical excision was performed in 18 growing lesions. Regressing lesions were left untreated. Classic histopathologic features and diagnosis were blindly recorded in both biopsies and surgical specimens.

Results:

On a clinical and a histologic basis, 32 lesions were assessed as KA and 11 as SCC. Features that indicated malignancy were observed in both groups, but the probability of SCC was 31 times higher in tumors with five or more of such features. Several of the histologically atypical lesions were found to regress.

Conclusion:

SCCs and KAs have more pathologic similarities than differences, especially in the proliferative phase. The combination of the most useful features did not allow the nosologic diagnosis in difficult cases but helped. Differential diagnosis was easier to determine after the 1-month follow up. Complete surgical excision should be indicated in nonregressing and growing lesions.

Oral contraceptives and skin cancer: is there a link?

The skin expresses estrogen, progesterone, and androgen receptors. In the presence of steroid hormones, such as those contained in oral contraceptives, the skin likely responds to hormonal signals that control the cell cycle, apoptosis, DNA replication, and other cellular functions. Some estrogen-responsive pathways have the potential to promote tumor development, including the augmentation of epidermal growth factor signaling, the expression of proto-oncogenes, and inhibition of apoptosis. The question of whether oral contraceptives increase the risk for the development of skin cancer, particularly melanoma, is still an area of concern. This paper reviews the available evidence, the bulk of which suggests that while the skin responds to estrogens, progestins, and androgens, these responses do not significantly increase the risk of developing skin cancer when estrogen exposure is not excessive.

Immunophenotypic analysis of the p53 gene in non-melanoma skin cancer and correlation with apoptosis and cell proliferation

BACKGROUND

Sunlight precipitates a series of genetic events that lead to the development of skin cancers such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The p53 tumour suppressor gene, which plays a pivotal role in cell division and apoptosis, is frequently found mutated in sunlight-induced skin tumours.

OBJECTIVE

To investigate the immunoreactivity of the p53 gene in non-melanoma skin cancers and to correlate its expression with apoptotic and cell proliferation markers.

METHODS

We analysed 35 non-melanoma tumours including 19 BCCs and 16 SCCs from sun-exposed skin areas. p53 protein expression was studied immunohistochemically using the DO7 monoclonal antibody against wild-type and mutant p53 forms. The percentage of p53-immunopositive nuclei was measured by image analysis. Cell proliferation and apoptosis were also assessed by image analysis following Ki-67 immunostaining and application of the TUNEL method on paraffin sections, respectively.

RESULTS

The percentage of p53-expressing cells varied from 3.5 to 90 in BCCs (median value 54.4%) and from 3.7 to 94 in SCCs (median value 40.3%). The mean value of Ki-67-positive cells was comparable in both groups of tumours with a mean value of 40.6% in BCCs and 34.6% in SCCs. Conversely, the TUNEL assay showed sporadic staining of apoptotic cells within the tumours with a mean value of 1.12% in BCCs and 1.8% in SCCs. p53 protein expression was correlated positively with cell proliferation (r = 0.75, P = 0.000001) and negatively with apoptosis (r = -0.23, P = 0.05).

CONCLUSION

p53 immunoreactivity was high in the majority of the skin carcinomas examined and correlated positively with cell proliferation and negatively with apoptosis. The p53 protein overexpression appears to be related to an inactivated protein resulting from mutations of the p53 gene or other unclear molecular mechanisms.

Biological behavior of keratoacanthoma and squamous cell carcinoma: telomerase activity and COX-2 as potential markers

Distinguishing keratoacanthoma from squamous cell carcinoma is a persistent issue in pathology practice. Solitary keratoacanthoma is a self-limiting lesion as opposed to rather aggressive clinical behavior of squamous cell carcinoma. Several markers were studied to understand their biology and to separate these two lesions on a firm basis, but without much success. In this study, we plan to utilize recent markers such as telomerase activity and cyclooxygenase-2 (COX-2) along with more established marker p53 in understanding the biologic differences between keratoacanthoma and squamous cell carcinoma. We studied 17 well to moderately differentiated squamous cell carcinoma and 24 early proliferative phase keratoacanthoma by immunohistochemistry for the expression of p53 protein, COX-2 and telomerase activity. Higher telomerase activity was found in 11/17 squamous cell carcinoma (65%) compared to 4/24 (17%) of keratoacanthoma. Similarly, stronger expression of p53 and COX-2 was detected in 12 (71%) and 11 (65%) cases of squamous cell carcinoma compared to 2 (8%) and 2 (8%) cases of keratoacanthoma respectively. A highly significant 'P' value was obtained for telomerase activity (0.001), p53 (0.000), and COX-2 (0.001). Telomerase activity, COX-2, and p53 expression provide evidence that keratoacanthoma and squamous cell carcinoma are indeed distinct entities and also help in discriminating these two lesions, which closely resemble each other on conventional morphology. Although these markers present new insights into the biologic variation of keratoacanthoma and squamous cell carcinoma, they are of limited value for routine application in histological distinction of these two lesions. The differential expression of markers also explains the sustained proliferation observed in squamous cell carcinoma, compared to a shorter lifespan and involution in keratoacanthoma.

The potential role of abnormal E-cadherin and alpha-, beta- and gamma-catenin immunoreactivity in the determination of the biological behaviour of keratoacanthoma

BACKGROUND

Failure of E-cadherin and its associated proteins alpha-, beta- and gamma-catenin is believed to lead to disruption of cell-cell adhesion and to contribute to neoplasia.

OBJECTIVES

To determine the pattern of E-cadherin and alpha-, beta- and gamma-catenin immunostaining in keratoacanthoma (KA) and to evaluate its potential value in routine histopathology in differentiating KA with benign from that with malignant biological behaviour.

METHODS

We examined the expression of E-cadherin and alpha-, beta- and gamma-catenin in KA and correlated the histopathological features with the immunohistochemical findings. Next, we compared the immunohistochemical findings of KA with those found in malignant (squamous cell carcinoma, SCC) and benign (warts) lesions. In addition to the established histopathological criteria we used the Ki-67 index, a well-known marker of cell proliferation. Immunoperoxidase staining of E-cadherin and alpha-, beta- and gamma-catenin, and Ki-67 determination, were performed in paraffin-embedded sections of 12 KAs taken from archival material. On reviewing the histology, seven of the 12 KAs were characterized as 'classical' KA, and the rest as 'borderline' KA or KA resembling SCC. Additionally, 28 well, nine moderately and five poorly differentiated SCCs and 20 warts were examined.

RESULTS

Most 'classical' KAs (79-86%) showed normal membranous immunostaining and a low Ki-67 index. The remaining 'classical' KAs showed abnormal expression, in a staining pattern resembling that of well-differentiated SCC. All 'borderline' KAs showed a high Ki-67 index (> 40%) and abnormal expression of the adhesion molecules studied, identical to that of poorly differentiated SCC. Expression of E-cadherin and alpha-, beta- and gamma-catenin was found to be more frequently abnormal in 'borderline' KA compared with that in 'classical' KA (P < 0.05). Among E-cadherin and alpha-, beta- and gamma-catenin expression and Ki-67 index, only the expression of beta-catenin was more frequently found to be abnormal in total SCC than in total KA (P < 0.05). Expression of E-cadherin and alpha-, beta- and gamma-catenin was more frequently found to be abnormal in well-differentiated SCC than in 'classical' KA (P < 0.05). In total, as well as in 'classical' or 'borderline' KA, an agreement between expression of E-cadherin and of catenins was seen.

CONCLUSIONS

These findings suggest that E-cadherin and catenins may be very helpful in distinguishing between 'classical' and 'borderline' KA, as the expression of these adhesion molecules in 'classical' KA is identical to that found in normal epidermis, overlapping with well-differentiated SCC in some cases. In 'borderline' KA, expression of adhesion molecules is identical to that in poorly differentiated SCC.

Overexpression of transforming growth factor-beta3 immunohistochemical staining in extramammary Paget's disease, but downregulated expression in Bowen's disease

BACKGROUND

The role of transforming growth factor-beta (TGF-beta) in carcinogenesis is complex, with some reports indicating a tumor inhibition role and others indicating a tumor promotion role. In particular, TGF-beta3 is thought to play a key role in controlling epithelial homeostasis. Immunopositive p53 has been demonstrated in a variety of human malignant tumors and its role in oncogenesis and tumor progression is thought to be important. Extramammary Paget's disease (EPD) and Bowen's disease are skin cancers of unknown histogenesis.

OBJECTIVE

To clarify the role of TGF-beta3 and p53 in EPD and Bowen's disease and to better understand the origin of these disorders.

METHODS

Specimens were obtained from 12 patients with EPD and 12 patients with Bowen's disease seen at our clinic between 1993 and 2000. TGF-beta3 and p53 immunohistochemical staining was performed.

RESULTS

In three of the 12 EPD patients and five of the 12 Bowen's disease patients, positive p53 staining was detected. In contrast, TGF-beta3 overexpression was detected in all EPD patients, whereas downregulated TGF-beta3 expression was detected in all Bowen's disease patients.

CONCLUSIONS

The present data suggest different roles for TGF-beta3 in abnormal epidermal cells in EPD and Bowen's disease. Thus, TGF-beta3 expression may be modulated differently via a p53-dependent or -independent pathway in the pathogenesis of EPD and Bowen's disease. Moreover, high TGF-beta expression appears to be a useful indicator of tumor activity in EPD.

Spontaneous regression of merkel cell carcinoma: a comparative study of TUNEL index and tumor-infiltrating lymphocytes between spontaneous regression and non-regression group

Some Merkel cell carcinomas (MCC) have been reported to regress spontaneously. To clarify the mechanisms of spontaneous regression (SR) of MCC, we analyzed the TUNEL index, the labeling index of proliferating cell nuclear antigen (PCNA), the labeling index of bcl-2 protein, and the expression of p53 of the tumor cells. We also evaluated the number of infiltrating lymphocytes surrounding the tumor in the tissue specimens. Among seven patients with MCC (SR: n=4; non-regression (NR): n=3), the TUNEL index in the SR group was significantly higher than that in NR group (5.2 and 2.0%, respectively). In addition, the number of lymphocytes around the tumor nests was also significantly increased in the SR group compared to NR group (1576 and 663 cells/mm(2), respectively). Most of the infiltrating lymphocytes were UCHL-1 positive T-cells. There were no significant differences of the PCNA labeling index, the bcl-2 protein labeling index, and the expression p53 between SR and NR group. These results indicate that apoptosis and local T-cell mediated immune response might be involved in spontaneous regression of MCC.

Relationship of p53 mutations to epidermal cell proliferation and apoptosis in human UV-induced skin carcinogenesis

Human skin is continually subjected to UV-irradiation with the p53 gene playing a pivotal role in repair of UV-induced DNA damage and apoptosis. Consequently, p53 alterations are early events in human UV-induced skin carcinogenesis. We studied 13 squamous cell carcinomas (SCC), 16 actinic keratoses (AK), 13 samples adjacent to an AK (chronically sun-damaged), and 14 normal-appearing skin samples for p53 mutation, p53 immunostaining (IHC), apoptosis (in situ TUNEL and morphology), and proliferation (PCNA). The frequency of p53 mutation increased from 14% in normal skin, to 38.5% in sun-damaged skin, 63% in AK, and 54% in SCC. p53 IHC increased similarly. Apoptosis (TUNEL) increased from 0.06 +/- 0.02%, to 0.1 +/- 0.2, 0.3 +/- 0.3, and 0.4 +/- 0.3 in normal skin, sun-damaged skin, AK, and SCC, respectively. Apoptosis was strongly correlated with proliferation (i.e., TUNEL and PCNA, r = 0.7, P < 0.0001), and proliferation was significantly increased in the progression from normal skin to SCC. Bax was significantly increased in SCC compared to AK. These data imply that apoptosis in samples with a high frequency of p53 mutation may not necessarily be p53-dependent. We suggest that there is a mechanism for apoptosis in response to increased cellular proliferation that is p53-independent.

Overexpression of p2lWaf1/Cip1 immunohistochemical staining in Bowen's disease, but not in disseminated superficial porokeratosis

Disseminated superficial porokeratosis (DSP) consists of multiple small lesions of porokeratosis. Although the pathogenesis of DSP remains unclear, localized cloning of abnormal epidermis has been hypothesized. Malignant cutaneous neoplasms, especially Bowen's disease, have been frequently reported in DSP. Immunopositive p53 has been demonstrated in a variety of human malignant tumours, and its role in oncogenesis and tumour progression is thought to be important. p21Waf1/Cip1 is thought to mediate the signal of p53 induced by DNA damaging agents to arrest the cell cycle. To clarify the role of p53 and p21Waf1/Cip1 in Bowen's disease and DSP, we analysed 12 cases of Bowen's disease and eight cases of DSP by immunohistochemistry. In five of the 12 Bowen's disease patients and two of the eight DSP patients, positive p53 staining was detected. In contrast, whereas p21Waf1/Cip1 overexpression was detected in all Bowen's disease patients, it was not seen in DSP. The present data suggest that p53 immunostaining provides relevant information concerning the pathogenesis of Bowen's disease and DSP. Furthermore, high p21Waf1/Cip1 expression appears to be a useful indicator of tumour activity in Bowen's disease.

p53 gene mutations in squamous cell carcinoma occurring in scars: comparison with p53 protein immunoreactivity

We determined the relationship between p53 expression and p53 gene mutations in squamous cell carcinoma occurring in scars and unrelated to UV light irradiation. We analyzed biopsy specimens obtained from three patients with squamous cell carcinoma. A monoclonal antibody against p53 (DO-7) was used for the immunohistochemical analysis. p53 gene mutations were detected by the polymerase chain reaction and single-strand conformation polymorphism analysis and direct DNA sequencing. p53 overexpression was observed in atypical squamous cells of one case. Those of two other cases, however, showed negative immunoreactivity to p53. Exon 6 of the p53 gene in all three cases and exon 7 in one case showed electrophoretic mobility shifts in polymerase chain reaction and single-strand conformation polymorphism analysis. DNA sequencing analysis showed a missense mutation and a silent mutation in exon 6 of the case with p53 overexpression, a three-base deletion in exon 6 of one case with no p53 overexpression, and a three-base deletion in exon 6 and a missense mutation in exon 7 of another such case. Although immunohistochemical overexpression of p53 has been thought to result from p53 gene mutations, our results suggest that negative immunoreactivity to p53 also can result from p53 gene mutations, for example, short gene deletions.

p53 expression in skin carcinogenesis and its relationship to cell proliferation and tumour growth

The immunoreactivity of p53 protein was studied in relation to tumour development, histopathological characteristics, cell proliferation, and basement membrane organisation following the induction of skin carcinogenesis in tumour-sensitive and -resistant mouse strains by ultraviolet (UV) irradiation or 7,12-dimethylbenz(a)anthracene (DMBA). In non-neoplastic skin exposed to UV irradiation or DMBA, p53 immunoreactivity was observed in nearly 50% of the basal layer cells. These cells were morphologically and histochemically indistinguishable from the p53-negative cells, occurring similarly in the tumour-producing and the tumour-negative mouse strains and regardless of subsequent tumour formation. In induced epidermal hyperplasia and in benign tumours, p53-positive and proliferating cells constituted 40-50% of all cells in the basal layer, while superficial cells were p53 negative. In dysplastic epidermis, p53-positive cells and proliferating cells were seen in all cell layers. In the case of squamous cell carcinomas, p53-positive proliferating cells in differentiated neoplasms were localised close to the basement membrane and, more frequently, in border areas showing invasion and basement membrane destruction. In horn cysts, centrally located cells were non-proliferating and p53 negative. In moderately differentiated neoplasms, proliferating cells were located closer to the basement membrane, while p53-positive cells were distributed diffusely in the neoplasm. In poorly differentiated neoplasms, p53-positive cells were more common than proliferating cells and were arranged in a diffuse pattern. The results showed that the number and location of p53-positive cells depended upon histology, with a close relationship to tumour type and degree of malignancy, but not on the mode of induction, nor on the animal strain or the relationship to subsequent tumour formation.

Squamous cell cancer: a practical approach

Cutaneous squamous cell carcinoma (SCC) is the second most common form of skin cancer and is treated frequently by dermatologists. For many years, the level of knowledge regarding treatment of SCC has taken a backseat to the treatment of basal cell carcinoma and malignant melanoma. As dermatologists become more surgically proficient and assume a leading role in the surgical care for cutaneous carcinoma, a thorough knowledge of the appropriate management of SCC is of paramount importance. In particular, it is essential to recognize that, unlike basal cell carcinoma, certain SCC have a significant metastatic potential and require more comprehensive care. This review targets the etiology, pathogenesis, clinical presentation, histopathology, and treatment of SCC. Particular attention is focused on providing appropriate care for SCC and recognizing and arranging appropriate management for high risk SCC.

p53 tumor suppressor gene protein expression in premalignant and malignant skin lesions of kidney transplant recipients

BACKGROUND

Kidney transplant recipients have an increased incidence of skin cancer, the cause of which is likely multifactorial. Inactivation of the tumor suppressor gene p53 protein may be important. Chemoprophylaxis of skin cancer with retinoids is beneficial in these patients.

OBJECTIVE

Our purpose was to investigate the immunohistochemical expression of p53 protein in premalignant and malignant cutaneous lesions in kidney transplant recipients and the effect of low-dose etretinate on p53 expression.

METHODS

Paraffin sections were stained with the monoclonal antibody DO-7.

RESULTS

Immunoreactivity of p53 was observed in 59% of basal cell carcinomas and more than 60% of squamous cell carcinomas, Bowen's disease, dysplastic lesions, and viral warts. No demonstrable effect of etretinate on p53 expression could be determined.

CONCLUSION

The high prevalence of p53 immunoreactivity in premalignant and malignant skin lesions of kidney transplant recipients supports a role for p53 protein in skin cancer. This could be caused by mutation of the p53 gene, inactivation, or failure of degradation of p53 protein.

Vulvar basal cell carcinoma

BACKGROUND

Vulvar basal cell carcinoma is a rare neoplasm that often displays aggressive biologic behavior. Recurrence after simple excision is common, and metastases have been reported. Early diagnosis is essential and rests upon histopathologic examination of biopsy specimens, since the clinical appearance of these neoplasms may be deceptively innocent.

CASE

A 65-year-old woman was seen with a nonhealing skin lesion on the right vulva. Physical examination revealed a 0.3 X 0.3 cm crusted papule on the right labium majus. A saucerization biopsy was performed. Histopathologic examination of the biopsy specimen revealed basal cell carcinoma. The patient underwent Mohs micrographic excision of the tumor, the total extent of which measured 0.9 X 1.8 cm.

CONCLUSION

Vulvar basal cell carcinoma is a rare but important consideration in the differential diagnosis of cutaneous vulvar lesions. Accurate diagnosis depends upon a high index of suspicion, biopsy, and histopathologic examination. Mohs micrographic excision is the treatment of choice.

An immunohistochemical study of p53 protein expression in classical Kaposi's sarcoma

The present study was performed to determine the frequency of p53 protein immunoreactivity in classical Kaposi's sarcoma (KS) as a whole and in relation to the histological subtypes which are considered to correspond to the developmental stages of the tumor. The accumulation of p53 protein was studied immunohistochemically using monoclonal antibody BP53-12 on formalin-fixed paraffin-embedded sections of 36 KS lesions, of which 14 were classified histologically as early type and 22 as spindle-cell or mixed type. No positive immunoreactivity was detected in any of the 14 early-type lesions. Among the 22 spindle-cell and mixed variants, positive staining was detected in 5-10% of the tumor cells in one lesion, 1-5% of the cells in six lesions, and in < 1% of the cells in two lesions. These very small percentages of positively stained cells in less than half of the cases of the spindle-cell and mixed variants do not support a significant role for p53 in tumor progression and evolution in KS.

Loss of heterozygosity analysis of keratoacanthoma reveals multiple differences from cutaneous squamous cell carcinoma

Keratoacanthomas (KAs) resemble squamous cell carcinomas (SCCs) except that, unlike SCCs, after a period of rapid growth over a few months they involute completely. The basis of their regressing natural history is not known. We have examined keratoacanthomas and another benign cutaneous tumour, the basal cell papilloma (BCP), for loss of heterozygosity (LOH) at a number of loci that are frequently lost in SCCs and other skin tumours. The frequency of LOH for both KAs and BCPs was low, with only isolated losses identified at 9p, 9q and 10q in KAs [fractional allelic loss (FAL) was 1.3%], and at 9p and 17p in BCPs (FAL was 0.4%). This contrasts with previous work showing a FAL of 32% in SCC and 46% in actinic keratoses. The results show a clear difference between KA and SCC and do not support the hypothesis that KAs are SCCs that regress as a result of external (host) influences but rather suggest that KAs and SCCs are different de novo. LOH around the locus implicated in the multiple self-healing epitheliomata of Ferguson-Smith (9q22-q31) was shown in only 1 of 11 KAs.

Spontaneous regression of human melanoma/nonmelanoma skin cancer: association with infiltrating CD4+ T cells

Spontaneous regression occurs in some human malignant melanomas and basal cell carcinomas (BCCs). We have compared the cellular infiltrate in regressing and nonregressing tumors in order to analyze the mechanism by which regression occurs. Regressing primary melanomas and BCCs were infiltrated with a larger number of CD4+, but not CD8+, T lymphocytes than were seen in nonregressing tumors. The number of interleukin 2 receptor-positive (early activation marker) but not transferrin receptor-positive (intermediate activation marker) T cells was increased, indicating that the infiltrating T cells were activated. Large numbers of Langerhans cells, macrophages, and other class II major histocompatibility complex (MHC)-expressing cells were present but were not increased in the regressing tumors. There were no detectable B lymphocytes, and the regressing tumor cells displayed levels of HLA-DR expression similar to those of the nonregressing tumors. Comparison of squamous cell carcinoma (SCCs) with keratoacanthomas (KAs), which are likely to be a spontaneously regressing form of SCC, also showed increased infiltration of activated CD4+, but not CD8+, T cells within the KA. A murine ultraviolet (UV)-induced squamous tumor that spontaneously regresses when transplanted into immunocompetent syngeneic mice was also infiltrated with increased numbers of activated CD4+, but not CD8+, T cells prior to and during rejection. These results indicate that spontaneous regression of human skin tumors is likely to be immunologically mediated, and that CD4+ T lymphocytes seem to mediate this regression.

Cell cycle regulators in the keratinocyte (cyclin-cdk)

It has recently become clear that cyclin-dependent kinase (cdk) complex regulates the cell cycle by phosphorylating Rb protein, a tumor suppressor protein. It is likely that this complex is a target of various growth factors and anti-growth factors (UV, TGF-beta etc.) in keratinocyte (KC). It has also been suggested that abnormalities in the cell cycle regulating mechanism such as increased activity of cyclin-cdk due to mutation of p53, a tumor suppressor gene, and overexpression of cyclin D may be concerned with carcinogenesis of KC. Thus, recent studies indicate that the cyclin-cdk complex is a common target of proliferation and carcinogenesis in KC.

Differential diagnosis of keratoacanthomas and squamous cell carcinomas: diagnostic value of DNA image cytometry and p53 expression

DNA-cytometry and immunohistochemistry with the anti-p53 antibody DO-1 was performed in 24 keratoacanthomas (KA) and 21 squamous cell carcinomas (SCC) (13 well-differentiated, 8 moderately differentiated) to establish the possible value of these methods for the differential diagnosis of both epithelial tumors. Aneuploidy was detected in 1 (4%) KA and 12 (57%) SCC (p < 0.05). In the latter tumors, histologic grade was associated with an abnormal DNA-content. Six (46%) well and 6 (75%) moderately differentiated SCC were shown to be aneuploid. Over-expression of p53 protein was found in 16 (76%) SCC and 14 (66%) KA (p > 0.05; not significant). However, quantification of p53 expression by evaluating both the intensity of immunostaining and the number of cells with over-expression by means of an immunoreactivity score (IRS) showed significant differences (p < 0.05). There was no correlation of p53 over-expression and aneuploidy in the tumors examined. The analysis of ploidy and immunostaining with anti-p53 antibodies may give useful additional information regarding the differential diagnosis of SCC and KA, if only aneuploidy or a high IRS are considered.

Evidence that regression in keratoacanthoma is immunologically mediated: a comparison with squamous cell carcinoma

Recent research observations suggest that the keratoacanthoma (KA) is a form of resolving squamous cell carcinoma (SCC). The mechanism by which this resolution takes place has not been fully explored, although it may have an immunological basis. To investigate this, we compared 15 clinically and histologically diagnosed KAs and 15 SCCs with regard to cellular infiltrate and keratin expression. We found that KAs have significantly higher numbers of CD3+ and CD4+ cells invading their epidermal component than SCCs. The T lymphocytes infiltrating KAs were more immunologically active, as greater numbers expressed the interleukin-2 receptor (IL-2R) than those in SCCs. It is of interest that CD36 was expressed by a significantly greater proportion of tumour cells within KAs than SCCs. This was also the case for the intercellular adhesion molecule ICAM-1, and the differentiation marker keratin 10. Overall, these findings suggest that KA regression is immunologically mediated, with activated (IL-2R+) CD4+ T lymphocytes and adhesion molecules playing a pivotal role in the immune response.

TP53 tumor suppressor gene and skin carcinogenesis

The tumor suppressor gene TP53 encodes for a nuclear phosphoprotein involved in the control of cell proliferation, particularly in stressed cells. TP53 gene mutations are the most frequent genetic event found in human cancers. Most mutations locate in the highly conserved domains of the gene. Their localizations vary according to the tissue and tumor type, but define some hot spot regions that may have a certain degree of tissue specificity. In certain cases, the type of nucleotide substitutions observed can help to find the carcinogenic agent. In recent years, TP53 gene mutations have been frequently observed in human skin tumors. In epithelial carcinomas, they involve mainly exons 5, 7, and 8. Interestingly, many are C to T transitions at dipyrimidine sites; particularly, one can find CC to TT double-base changes that are known to be specific to ultraviolet radiation. These data confirm at the molecular level the role of ultraviolet radiation as an important etiologic factor in the genesis of these lesions. The high incidence of TP53 mutations suggest that they play a role in keratinocyte transformation. Nevertheless, this event has not yet been defined as an early or late event. In melanomas, most studies have shown the detection of the p53 protein by immunohistochemistry, suggestive of the presence of a mutation in the gene prolonging the protein half-life. Anti-p53 reactivity is frequent in these tumors and seems to correlate with tumor aggressiveness. Confirmation and characterization of TP53 gene mutation at the DNA level would help to precisely define the role of this gene in the development of these tumors.

p53 Protein expression in squamous cell carcinomas from sun-exposed and non-sun-exposed sites

BACKGROUND

In sun-exposed nonmelanoma skin cancers, observation of specific p53 gene mutations implicate the role of UV radiation-induced mutations in the pathogenesis of these tumors. Immunohistochemical p53 protein overexpression and p53 gene mutation have been frequently considered related events.

OBJECTIVE

We investigated the differences in p53 immunostaining in squamous cell carcinomas (SCCs) with varying degrees of differentiation, from both chronically sun-exposed and sun-protected sites of the skin.

METHODS

Twenty-six SCCs (15 UV-related and 11 UV-unrelated) and five specimens of Bowen's disease (in situ SCC) from sun-exposed skin were examined by means of BP53-12-1 monoclonal antibody immunohistochemistry.

RESULTS

p53 Immunoreactivity was observed in 66.7% of sun-exposed, 54.5% of non-sun-exposed invasive SCCs (Fisher's exact test, p = 0.689), and 80% of Bowen's disease specimens. In 50% of all samples, p53 positivity was more prominent in the proliferating periphery of the tumor with gradual loss of positivity as the cells differentiated.

CONCLUSION

The reliability of p53 immunohistochemistry needs further molecular genetic studies.

Diagnostic associations of p53 immunostaining in fine needle aspiration cytology of the breast

Duplicate cytospin preparations were made from 46 symptomatic breast fine needle aspirates. One of each pair was assigned to benign or malignant categories by one experienced observer as part of the "triple approach" patient assessment. The other was immunostained with DO7, a monoclonal antibody to recombinant p53 protein, and rated by another observer as positive or negative for nuclear staining, unaware of the cytodiagnosis. Positive controls included carcinomas known to have mutant p53, while negative controls were of the reagent substitution type. Of the 26 aspirates with a benign cytodiagnosis (verified by the triple approach), 23 were p53 protein-negative and three positive. Of the 20 with a malignant cytodiagnosis (histologically confirmed), six were p53 protein-negative and 14 positive (exact P < 0.0001). As a diagnostic test this would give 70% sensitivity and 88% specificity.

Keratoacanthoma

The keratoacanthoma is a common cutaneous neoplasm that most often occurs on sun-exposed sites in light-skinned persons of middle age or older. It is considered the prototype of cutaneous pseudo-malignancies because it is a rapidly growing tumor with a histologic pattern resembling squamous cell carcinoma. It may be best viewed as an aborted malignancy that only rarely progresses into an invasive squamous cell carcinoma. It is most likely derived from hair follicle cells. The common type of keratoacanthoma and its many variants are discussed with emphasis on clinical and histologic features, biologic behavior, and response to therapy.