Evidence that regression in keratoacanthoma is immunologically mediated: a comparison with 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.

A clinical and biological review of keratoacanthoma

Keratoacanthoma (KA) is a common skin tumour that remains controversial regarding classification, epidemiology, diagnosis, prognosis and management. Classically, a KA manifests as a rapidly growing, well-differentiated, squamoid lesion with a predilection for sun-exposed sites in elderly people and a tendency to spontaneously regress. Historically, KAs have been considered a variant of cutaneous squamous cell carcinoma (cSCC) and are often reported as KA-type cSCC. However, the penchant for regression has led many to categorize KAs as biologically benign tumours with distinct pathophysiological mechanisms from malignant cSCC. The clinical and histopathological similarities between KA and cSCC, particularly the well-differentiated variant of cSCC, have made definitive differentiation difficult or impossible in many cases. The ambiguity between entities has led to the general recommendation for surgical excision of KAs to ensure a potentially malignant cSCC is not left untreated. This current standard creates unnecessary surgical morbidity and financial strain for patients, especially the at-risk elderly population. There have been no reports of death from a definitive KA to date, while cSCC has an approximate mortality rate of 1·5%. Reliably distinguishing cSCC from KA would shift management strategies for KAs towards less-invasive treatment modalities, prevent unnecessary surgical morbidity, and likely reduce associated healthcare costs. Herein, we review the pathophysiology and clinical characteristics of KA, and conclude on the balance of current evidence that KA is a benign lesion and distinct from cSCC.

β-Catenin and CD44 Expression in Keratoacanthoma and Squamous Cell Carcinoma of the Skin

CD44 and β-catenin are adhesion molecules expressed on a wide variety of cells. Failure of this expression is believed to lead to disruption of cell-cell adhesion and to neoplasia. The aim of this study was to investigate the staining intensity of CD44 and β-catenin in keratoacanthomas and squamous cell carcinomas of the skin. The proliferation index, PCNA staining, was also evaluated in these cases. The abnormal expression of β-catenin significantly predominated in squamous cell carcinomas (n = 20, 76.9%) compared with keratoacanthomas (P = 0.002, χ2 = 7.8). Most keratoacanthomas (n = 11, 61.1%) more frequently showed strong staining intensity with CD44 compared with squamous cell carcinoma (P = 0.001, χ2 = 13.7). The proliferation index was higher in squamous cell carcinoma (P = 0.000, χ2 = 12.8). These findings suggest that CD44 and β-catenin expression may have an important role in the development of malignancy and in the determination of biological features of keratoacanthoma and squamous cell carcinoma of the skin.

The occurrence of non-melanoma malignant skin lesions and non-cutaneous squamous-cell carcinoma among metastatic melanoma patients: an observational cohort study in Denmark

BACKGROUND

Inhibitors of mutant BRAF are emerging as standard of care in patients with metastatic melanoma who carry relevant oncogenic mutations. However, BRAF inhibitors are found to induce cutaneous squamous cell carcinoma (cuSCC). Population-based background rates of cuSCC and non-cutaneous squamous cell carcinoma (non-cuSCC) in the metastatic melanoma population may contextualize safety signals from randomized clinical trials or the clinics. However, these background rates are lacking.

METHODS

We conducted a historical cohort study to evaluate the background rates of new-onset non-melanoma skin lesions and non-cuSCC among 2,814 metastatic malignant melanoma patients diagnosed in 1997-2010, identified through the Danish Cancer Registry and the National Pathology Registry. Patients were excluded if they had a history of cancer before the metastatic melanoma diagnosis, other than skin cancers. We determined the incidence of non-melanoma malignant skin lesions and non-cuSCC that occurred post metastatic melanoma diagnosis, censoring patients at death, emigration, or December 31, 2011 (end of study period), whichever came first.

RESULTS

The median age at metastatic melanoma diagnosis was 64 years. Over 40% of patients died within one year of metastatic diagnosis and ~70% died within 5 years. The percentages of patients with prior history or prevalent disease at metastatic melanoma diagnosis included: 8.6% with cuSCC or basal cell carcinoma (BCC), 3.9% with actinic keratosis (AK), and 0.7% with Bowen's disease. No patients had past or current non-cuSCC per study exclusion criterion. The incidence of non-melanoma skin lesions during the 6 months post-metastatic melanoma diagnosis was as follows: BCC, 1.8% (42.5 per 1000 person-years [PY]); AK, 0.8% (18.6 per 1000 PY); cuSCC, 0.1% (1.7 per 1000 PY); Bowen's disease, 0.04% (0.8 per 1000 PY); and keratoacanthoma (KA), 0%. Non-cuSCC was observed in 3 patients (0.1%; 2.5 per 1000 PY) at 3 sites: bronchi, heart and lung.

CONCLUSION

CuSCC and non-cuSCC were rare events among metastatic melanoma patients.

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.

Possible Spontaneous Regression of a Metastatic Lesion of Keratoacanthoma-Like Squamous Cell Carcinoma in a Regional Lymph Node

We report herein a case of keratoacanthoma-like squamous cell carcinoma in an 82-year-old male that showed regional lymph node metastasis followed by self-regression of the metastatic lesion. This case is consistent with the previously reported observation that tumors compatible with the clinical features of keratoacanthoma may have malignant biological potential, however, it also demonstrates that even metastatic lesions may exhibit self-regression similar to that observed for primary lesions. Despite the view that keratoacanthoma-like squamous cell carcinoma may represent a variant of squamous cell carcinoma, occasionally it undergoes a unique clinical course.

[Complete regression of melanocytic nevi: correlation between clinical, dermoscopic, and histopathologic findings in 13 patients]

BACKGROUND

The complete regression of melanocytic tumors, confirmed by histology, has rarely been reported in the literature. It is very difficult to determine the malignant or benign nature of a regressed tumor, and on occasions, the only indication of malignancy is the subsequent development of metastasis.

MATERIAL AND METHODS

We performed a descriptive study of melanocytic nevi that had undergone complete, histologically confirmed regression prior to excision in the dermatology department of our hospital over a period of 3 years. We included only lesions in which dermoscopy performed prior to regression showed features that suggested benignity. We assessed various clinical, dermoscopic, histologic, and immunohistochemical features.

RESULTS

The mean time to complete regression was 6.4 months. The main dermoscopic patterns observed were reticular and mixed reticular/globular. Unlike what is generally seen in melanomas, the main histologic finding was the presence of fine or lamellar fibrosis. In all cases, there was a predominance of CD8+ T cells.

CONCLUSIONS

The clinical, dermoscopic, and histologic features of the melanocytic nevi studied suggest the existence of a highly characteristic form of tumor regression characterized by very rapid regression and the involvement of a cytotoxic mechanism.

The nuclear factor kappa B p50 subunit and cortactin as markers to distinguish between keratoacanthoma and well-differentiated squamous cell carcinoma

BACKGROUND

Distinguishing keratoacanthoma (KA) from well-differentiated squamous cell carcinoma (SCC) is sometimes difficult. Recent evidence indicates that the nuclear factor kappa B p50 subunit (p50) and cortactin might be useful to distinguish between these two conditions.

AIM

To verify whether p50 and cortactin are useful differentiation markers to distinguish between subungual KA and well-differentiated SCC.

METHODS

Immunohistochemistry using p50, cortactin and Ki-67 was performed on 20 patients with KA and 20 patients with facial well-differentiated SC. Ki-67 staining was also evaluated and scored.

RESULTS

Both p50 and cortactin had higher levels of expression in KA than in SCC. Both were localized to the basal-cell layer of KA, whereas they were scattered without polarity throughout the SCC lesions. Although the Ki-67 index was not significantly different between KA and SCC, the staining pattern also showed loss of polarity in SCC.

CONCLUSION

p50 and cortactin might be useful makers to distinguish between KA and well-differentiated SCC.

Sorafenib-induced premalignant and malignant skin lesions

PURPOSE

To review characteristics of patients who develop premalignant and malignant skin lesions while on sorafenib therapy and discuss implications for subsequent treatment of their primary malignancies.

BACKGROUND

Sorafenib is a newly developed multitargeted protein kinase inhibitor reported to induce a variety of adverse cutaneous effects, rarely including actinic keratoses, keratocanthomas, and squamous cell carcinomas (SCCs).

METHODS

Published reports of individuals who have developed cutaneous lesions demonstrating atypia of the epidermis are reviewed. In addition, a 77-year-old man who developed not only an SCC but also verrucas within one month of taking sorafenib monotherapy for metastatic adenocarcinoma of the lung is described.

RESULTS

Cutaneous lesions develop most commonly in Caucasian men older than 40 years without previous histories of skin cancer, within two weeks to three years of starting sorafenib therapy. Currently there is no definitive explanation for the relationship between sorafenib and cutaneous neoplasms. Management typically involves treatment of skin lesions with cryotherapy or excision with at least a brief discontinuation of sorafenib. In patients whose primary malignancies were responding well, sorafenib therapy was continued with close follow-up.

CONCLUSIONS

The possibility of rapidly developing actinic keratoses, keratocanthomas, verrucas, and SCC during treatment with sorafenib, warrants close dermatologic follow-up and a lower threshold for biopsy and treatment of suspicious cutaneous lesions. Development of a sorafenib-induced SCC is not an absolute contraindication for continued use of sorafenib therapy; however, the drug should be briefly discontinued until lesions are treated.

The immunoregulatory mechanisms of carcinoma for its survival and development

The immune system in patients detects and eliminates tumor cells, but tumors still progress persistently. The mechanisms by which tumor cells survive under the pressure of immune surveillance are not fully understood. This review is to present the evidence from clinical studies, showing a significant correlation of clinicopathological features of carcinoma with: (1) the loss of classical human leukocyte antigen class I, (2) the up-regulation of non-classical human leukocyte antigen class I, pro-apoptotic Fas ligand and receptor-binding cancer antigen expressed on SiSo cells I, and (3) the formation of immunosuppressive microenvironment by up-regulation of transforming growth factor-beta, Galectin-1, inhibitory ligand B7s, indoleamine 2,3-dioxygenase and arginase, as well as by recruitment of tumor-induced myeloid-derived suppressor cells and regulatory T cells. All of these factors may together protect carcinoma cells from the immune-cytotoxicity.

Keratoacanthoma: facts and controversies

The keratoacanthoma and its variants are clinically and histologically heterogenous. Some consider the keratoacanthoma to be benign, whereas others classify it as a subtype of squamous cell carcinoma. The keratoacanthoma is generally treated rather than observed for spontaneous resolution. This hampers evaluation of the true natural history of lesions diagnosed as keratoacanthoma. In addition, studies have not found a reliable marker to differentiate keratoacanthoma from squamous cell carcinoma. It currently remains unclear how the keratoacanthoma relates to squamous cell carcinoma, and continued investigation is necessary.

Expression of cell cycle and apoptosis regulatory proteins in keratoacanthoma and squamous cell carcinoma

Some authors view keratoacanthoma (KA) as a variant of squamous cell carcinoma (SCC), while others consider it a separate entity that must be distinguished from SCC. Involution displayed by KA is an important difference between these two entities. It has been suggested that apoptosis plays a role in the involution process of KA, although the exact trigger for it remains unclear. A hundred and fifty specimens were included in this study, 30 cases for each of the following groups: normal skin (NS), proliferative keratoacanthoma (pKA), regressing keratoacanthoma (rKA), well-differentiated squamous cell carcinoma (wdSCC), and poorly differentiated squamous cell carcinoma (pdSCC). They were immunohistochemically examined for the expression of p53, Ki-67, bak, and bcl-2. Significantly higher p53 and Ki-67 expressions were observed in all tumor lesions examined as compared with NS. There was higher bak expression in KAs compared to NS and a significant reduction of bak expression in pdSCC together with a significant reduction of bak expression in SCCs compared to pKA. Bcl-2 expression was similar in NS and SCCs, but was lower in rKA. We found a significant positive correlation between p53 and Ki-67, p53 and Bak in NS and examined skin tumors. Lower bcl-2 expression in conjunction with higher bak expression in rKA suggests a possible role of these apoptosis-regulating proteins in tumor regression. In contrast to this finding, a steady level of bcl-2 expression in pdSCC combined with lower bak expression levels and a high proliferation rate could contribute to progression and aggressiveness in these tumors. Bak and p53 expression is a sun-related and age-dependent process in NS and skin tumors.

p16 Expression in Keratoacanthomas and Squamous Cell Carcinomas of the Skin: An Immunohistochemical Study

Context.—Distinguishing between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is not an uncommon histologic diagnostic dilemma.

Objective.—To determine if p16 expression is useful in the differential diagnosis of SCC and KA.

Design.—We studied the expression of p16 by immunohistochemistry in 24 KAs, 24 infiltrating SCCs of the skin, 4 histologically indeterminate lesions, and 8 nonmalignant keratoses.

Results.—A range of immunohistochemical p16 expression was seen in KAs and SCCs in terms of the thickness of lesional staining and the percentage of cells staining. No significant difference in measures of p16 expression was identified among the KAs, the SCCs, the indeterminate lesions, or the benign keratoses.

Conclusions.—These findings suggest that p16 is not a useful marker to distinguish between KA and SCC, supporting the similarity between the 2 lesions; p16 alterations appear to play a role in the pathogenesis of both KA and SCC.

Possible key role of granzyme B in keratoacanthoma regression

It is still controversial whether keratoacanthoma is to be considered as a well differentiated variant of squamous cell-carcinoma or a separate entity. As opposed to malignant potential of squamous cell-carcinoma, keratoacanthoma is characterized by a spontaneous regression. However, in some cases, otherwise typical keratoacanthoma can behave aggressively showing the signs of perineural and perivascular invasion and metastases in regional lymph nodes. The most important feature that separates these two closely related entities is a tendency of keratoacanthoma to regress. Causes and detailed mechanism of this regression are still not completely elucidated. Within the past few years, it has become evident that the molecular events regulating cell survival and apoptosis are important contributors to the overall kinetics of benign and malignant cell growth. Immunological mechanisms have been implicated in a phenomenon of spontaneous tumor regression. Recent studies suggested that the tumor regression is dependent mainly on the immune response mediated by cytotoxic T lymphocytes (CD8+), together with helper T cells (CD4+). Cytotoxic T lymphocytes can kill tumor cells and mediate tumor regression in vivo through two distinct molecular mechanisms: Fas/Fas ligand and granzyme B/perforin mediated pathways. Tumor cells are capable of developing different escape mechanisms in order to overcome their sensitivity to apoptotic signals. However, granzyme B, contained in cytolytic granules released upon target cell recognition, can also cause tumor cell death and consequently tumor regression by direct damage to non-nuclear structures through a caspase-independent pathway. Therefore, we propose a key role of plasticity in the granzyme B mediated cell death pathway in the killing of changed tumor cells, resulting in keratoacanthoma regression through apoptosis or direct damage of tumor cells. On the other hand, insufficient activation of cytotoxic T lymphocytes and decreased release or activity of granzyme B could be responsible for squamous cell-carcinoma progression and occasional aggressive behavior in keratoacanthomas. As a first step in confirming or refuting our hypothesis, we suggest a thorough immunohistochemical study of the presence of granzyme B and its activity in keratoacanthoma and squamous cell-carcinoma samples. To our knowledge, no such study has been performed so far.

Transforming growth factor-beta1 immobilises dendritic cells within skin tumours and facilitates tumour escape from the immune system

Human skin tumours often regress spontaneously due to immune rejection. Murine skin tumours model this behaviour; some regress and others progress in syngeneic immunocompetent hosts. Previous studies have shown that progressor but not regressor skin tumours inhibit dendritic cell (DC) migration from the tumour to draining lymph nodes, and transforming growth factor-beta1 (TGF-beta1) has been identified as a responsible factor. To determine whether increased production of TGF-beta1 in the absence of other differences inhibits DC migration from the tumour and enables it to evade immune destruction, a murine regressor squamous cell carcinoma clone was transfected with the gene for TGF-beta1. This enhanced growth in vitro and in vivo, causing it to become a progressor. TGF-beta1 transfection reduced the number of infiltrating DCs by about 25%. Quantitation of CD11c+ E-cadherin+ (epidermally derived) DCs in lymph nodes determined that TGF-beta1 reduced the number of DCs that migrated from the tumour to undetectable levels. This was supported by showing that TGF-beta1 reduced DC migration from cultured tumour explants by greater than tenfold. TGF-beta1 transfection also reduced the number of infiltrating CD4 and CD8 T cells. Thus, TGF-beta1 production by skin tumours is sufficient to immobilise DCs within the tumour, preventing their migration to lymph nodes. This reduces the number of T cells that infiltrate the tumour, preventing regression. Thus, TGF-beta1 is a key regulator of whether skin tumours regress or progress.

Cyclobutane pyrimidine dimer formation is a molecular trigger for solar-simulated ultraviolet radiation-induced suppression of memory immunity in humans

We tested the hypothesis that DNA is a target for solar-simulated ultraviolet radiation (ssUVR)-induced suppression of the reactivation of memory immunity in humans. T4N5 liposomes contain the DNA repair enzyme T4 endonuclease V. This cleaves DNA at the site of ultraviolet radiation (UVR)-induced cyclobutane pyrimidine dimers (CPD), initiating DNA repair. It has previously been used to show that CPDs are a key molecular trigger for UVR-induced immunosuppression in mice. To determine whether CPD formation is involved in UVR immunosuppression in humans, nickel-allergic volunteers were irradiated with a range of doses of ssUVR. T4N5 or empty liposomes were then applied after irradiation. Nickel-induced recall immunity was assessed by reflectance spectrometry. T4N5 liposomes inhibited immunosuppression and prevented ssUVR from reducing the number of epidermal dendritic cells. T4N5 liposomes also reduced macrophage infiltration into irradiated epidermis. These studies show that enhanced removal of CPDs from human skin protects from immunosuppression, hence demonstrating that these photolesions are an important molecular event in ssUVR-induced immunosuppression in humans. CPDs also triggered loss of dendritic cells and infiltration by macrophages. It is possible that these changes to antigen presenting cells contribute to ssUVR induced suppression of recall immunity to nickel in humans.

Spontaneous regression of keratoacanthoma can be promoted by topical treatment with imiquimod cream

Imiquimod, the first member of a new class of immune response modifiers, is approved for the treatment of external genital and perianal warts. Recently, many clinical trials highlighted the potential of imiquimod as a treatment for other viral infections and cutaneous neoplasms. We report two cases of facial keratoacanthomas (KA) treated with topical 5% imiquimod cream. Patients were successfully cleared of KAs after treatment for 8 weeks. No recurrence occurred after a 1-year follow-up. Despite the fact that KAs are characterized by the potential for spontaneous regression, it is possible that a faster activation of CD4+ lymphocytes, via interferon release and cytokine secretion takes place after imiquimod application leading to KA regression.

Keratoacanthoma observed

Conventional advice for managing suspected keratoacanthoma is total excision because of concern that the lesion may be a squamous cell carcinoma and histological differentiation of the two lesions is difficult. Only isolated cases have been published where lesions have been observed, with photographic documentation, to spontaneous resolution. Over 11 years (1992-2002) the author made a primary clinical diagnosis of solitary keratoacanthoma in 19 patients based upon the history and lesion appearance. Two thigh skin graft donor site lesions, and one on the nose and one on the lower lip were excised when there was concern about their growth pattern. A fifth patient was not content to be observed and had the lesion curetted by an oncologist. The remaining 14 patients had observed lesions photographed sequentially until resolution. The commonest single site affected was the hand (five cases). The mean age was 65 years (42-86 years). The mean duration of the lesion at presentation was 9 weeks (4-28 weeks), and the mean time to resolution from appearance was 27 weeks (12-64 weeks). Mean follow-up after resolution was 3 years 5 months (range 9 months-8 years). No recurrences occurred. No scar revisions were necessary. Claims that resolved keratoacanthomas leave poor quality scars that may need surgical revision, were not confirmed in this illustrated series which is the largest published to date. The principles of observational management are outlined and the natural history of the condition and patterns of spontaneous resolution described.

Characterizing the protective component of the alphabeta T cell response to transplantable squamous cell carcinoma

There is increasing promise that cellular immune response may be manipulated to combat cancer; however, it is also clear that the immune response to cutaneous malignancy comprises different T cell activities that variably inhibit or promote tumor development. Thus, a better understanding of each of these activities is crucial to more effective clinical manipulation. To better characterize the protective anti-tumor effects of alphabeta T cells, we examined the growth of the transplantable squamous cell carcinoma (SCC) line, PDV, which is markedly inhibited in immunocompetent versusalphabeta T cell-deficient mice. We show that the protective response is composed of CD8(+) and interferon-gamma (IFNgamma)-producing CD4(+) cells, and that the most overt effects of these components on tumor growth in situ are to provoke overt focal necroses and to decrease the stromal bed. Tumors growing in the presence of any of these components also show reduced expression of Rae-1, a ligand for the activating NK receptor, NKG2D. Collectively, these data illustrate which components of the alphabeta T cell response against SCC have protective potential, and indicate which aspects of tumor physiology may be most susceptible to their activities.

The immunopathology of regression in benign lichenoid keratosis, keratoacanthoma and halo nevus

BACKGROUND

Regression is a phenomenon present in a variety of cutaneous lesions. It is likely that similar immunologic mechanisms explain the phenomenon of spontaneous regression occurring in the various lesions.

METHODS

Twenty-seven specimens, nine each of halo nevus, keratoacanthoma, and benign lichenoid keratosis, including three examples each of predominantly early, mid, and late regression were examined with antibodies to HLA-II, CD1a, CD3, CD4, CD8, CD20, CD34, CD56, and CD68.

RESULTS

Epidermotropism of inflammatory cells, including CD1a positive, CD68 positive, CD3 positive, and CD8 positive cells, was present in benign lichenoid keratosis and keratoacanthoma, but not in halo nevus. In halo nevus, the nests of halo nevus cells tended to be infiltrated by CD1a positive, CD68 positive, CD3 positive, and CD8 positive cells. The blood vessels exhibited endothelial cell swelling with luminal narrowing and disruption within the dermis of all lesions. The CD1a positive cells were increased in number in lesional epidermis except in keratoacanthoma lesions where the density of CD1a positive cells was increased in the epithelial lip, but decreased within the epithelial portion of the keratoacanthoma proper. Conversely, the CD8 positive cells were scarce in the dermis below the epithelial lip of the keratoacanthoma, but increased in the dermis of the neoplastic epithelium. CD1a positive cells were also seen throughout the dermal portion of the lesion, particularly at the lesion base. In halo nevus, the CD1a positive cells and CD68 positive cells within the lesions were larger than those in non-lesional skin, indicating activation. The composition of the inflammatory infiltrate varied within each lesion type according to stage of regression, but T-lymphocytes predominated.

CONCLUSION

Cytotoxic T-cells may be the final common denominator of regression in benign lichenoid keratosis, keratoacanthoma, and halo nevus. In halo nevus, cytotoxic T-cells may play the predominant role in regression. In keratoacanthoma and benign lichenoid keratosis, cytotoxic T-cells play a pivotal role, but additional mechanisms may also be involved in the phenomenon of regression. Benign lichenoid keratoses progress through stages of regression accompanied by varying proportions of inflammatory cells, including CD3, CD4, and CD8 positive T-lymphocytes, natural killer cells, macrophages and Langerhans cells.

Keratoacanthoma: A Clinico-Pathologic Enigma

BACKGROUND

Keratoacanthoma (KA) is an extraordinary entity. Once considered a benign neoplasm that resembled a highly malignant one (pseudomalignancy), it is now viewed in an opposite light as a cancer that resembles a benign neoplasm (pseudobenignity).

OBJECTIVE

The goal was to delineate the malignant potential of this neoplasm based on the author's experience and a review of recent data and research and to emphasize the KA as a possible part of an autosomal dominant familial cancer syndrome, the Muir-Torre syndrome.

METHODS

This is a review of the literature.

RESULTS

In this work, the KA is reviewed with recent advances emphasized.

CONCLUSION

KA is an abortive malignancy that rarely progresses into an invasive SCC. The KA may serve as a marker for the important autosomal dominant familial cancer syndrome, the Muir-Torre syndrome, as a result of a defective DNA mismatch repair gene.

High levels of Fas ligand and MHC class II in the absence of CD80 or CD86 expression and a decreased CD4+ T cell Infiltration, enables murine skin tumours to progress

It is still not clear why some tumours will be recognized and destroyed by the immune system, and others will persist, grow, and eventually kill the host. It has been hypothesized that tumour cells might evade immunological destruction by expressing Fas ligand (FasL), a molecule which induces apoptosis in Fas(+) target cells. However, the role of FasL in creating an immune privileged status within a tumour remains controversial. To determine whether FasL is associated with skin tumour progression, we developed a tumour model enabling us to compare two squamous cell carcinomas (SCC). One is a regressor SCC which spontaneously regresses after injection into syngeneic mice. The other is a progressor SCC which evades immunological destruction. Detailed flow cytometric analysis was used to study tumour cell expression of FasL, Fas, CD80, CD86 and MHC class II. We also analysed the percentage of apoptotic tumour cells in vivo using annexin V and correlated skin tumour progression with CD4 and CD8 T cell infiltration. Progressor tumours expressed high levels of FasL in vivo, which was virtually absent from regressor tumours. The percentage of progressor tumours expressing MHC II was significantly greater than regressor tumours, while neither tumour expressed CD80 or CD86 costimulatory molecules. Consistent with a regressor phenotype, the percentage of viable tumour cells was significantly lower for regressor compared to progressor tumours which coincided with a significantly larger CD4(+) T cell infiltrate into the tumour mass. The results suggest that progression of skin tumours occurs if tumour cells express high levels of MHC II but not costimulatory molecules such as CD80 or CD86. This implies that tumours may induce anergy in CD4(+) T cells via MHC II antigen presentation in the absence of costimulation. To ensure escape from the immune system, tumours may then kill these T cells via a FasL-dependent mechanism.

VCAM (CD-106) and ICAM (CD-54) adhesion molecules distinguish keratoacanthomas from cutaneous squamous cell carcinomas

Keratoacanthomas are rapidly growing benign epithelial derived neoplasms that may evolve into squamous cell carcinomas, or represent a variant of squamous cell carcinoma. ICAM (CD-54) is a ligand for the cell adhesion receptor LFA-1, shown to be important in immune stimulation that is upgraded in inflammatory cutaneous disorders. VCAM (CD-106) is an adhesion molecule normally found in stimulated endothelium, that plays a critical role in the migration of leukocytes. We examined the immunohistochemical expression of ICAM (CD-54) and VCAM (CD-106) in a series of 50 evolving, fully developed, resolving keratoacanthoma and well-differentiated and poorly differentiated squamous cell carcinoma to evaluate the possible temporal and pathogenic relation of these immune recognition markers and epithelial derived tumors. ICAM (CD-54) showed an increase in expression in the fully developed keratoacanthoma and was absent in the evolving and resolved keratoacanthoma. In the squamous cell carcinomas, expression was focally observed in the well-differentiated squamous cell carcinomas with a dramatic increase seen in the poorly differentiated squamous cell carcinomas. Similarly, VCAM (CD-106) was expressed in the fully developed keratoacanthoma and was absent in the evolving and resolved keratoacanthoma. Moderate expression for VCAM (CD-106) was seen in the well-differentiated squamous cell carcinoma, and intense expression was seen in the fully developed keratoacanthoma and poorly differentiated squamous cell carcinoma. As a group, keratoacanthoma and squamous cell carcinoma are immunophenotypically distinct. There is a temporal related increase in expression of VCAM (CD-106) in conjunction with the evolution of keratoacanthoma. Increased expression of both markers is seen with squamous cell carcinoma dedifferentiation. Application of these markers might be an important adjunct in predicting the biologic behavior and pathogenesis of these lesions.

Intralesional corticosteroid treatment of multiple eruptive keratoacanthomas: case report and review of a controversial therapy

BACKGROUND

Use of intralesional corticosteroids in the management of keratoacanthomas has been reported in older literature. Yet this therapy is no longer a commonly considered treatment option.

OBJECTIVE

To report management of a therapeutically challenging patient with multiple eruptive keratoacanthomas with intralesional corticosteriod treatment to revive awareness of this treatment option.

METHODS

A 55-year-old female with frequent episodes of multiple eruptive keratoacanthomas was treated with intralesional corticosteroids and methotrexate.

RESULTS

Intralesional corticosteroids successfully treated eruptive keratoacanthomas with complete regression and minimal scarring within 2-4 weeks.

CONCLUSION

Despite its limitations, intralesional corticosteroids may have a role in the treatment of select keratoacanthomas.

Inflammation is associated with progression of actinic keratoses to squamous cell carcinomas in humans

BACKGROUND

Squamous cell carcinoma (SCC) is a common skin tumour that may metastasize and lead to death. We have observed that before actinic keratoses (AK) progress to SCCs they may become tender and inflamed. In some of these, histological examination shows that they are, in fact, SCCs.

OBJECTIVES

To study the progression of AK to SCCs.

METHODS

We studied skin tumours from 50 patients with either asymptomatic AK, inflamed AK or SCCs, using immunocytochemistry. The diagnosis of each tumour was confirmed by histological examination.

RESULTS

Studies of differentiation using heat shock protein 27 showed a stepwise loss of differentiation as the tumours progressed from asymptomatic AK, through inflamed AK to SCCs. During the inflamed AK phase, there was a marked increase in T lymphocytes and Langerhans cells: the number of infiltrating cells diminished as progression to SCC occurred. There was an increase in immunoreactive p53 and the apoptosis inhibitor bcl-2 as tumours progressed from AK to SCCs, and a decrease in Fas and Fas ligand.

CONCLUSIONS

These studies have shown that progression from benign to malignant tumours may be associated with an inflammatory response, which appears to drive malignant conversion, but subsides rapidly following this conversion.

Comparison of oncostatin M expression in keratoacanthoma and squamous cell carcinoma

Oncostatin M (OSM) is a 28-kDa glycoprotein, produced by stimulated macrophages and T lymphocytes, that inhibits the proliferation and induces differentiation of a number of different cell lines derived from solid tumors. To determine whether keratoacanthoma (KA) is unique or a variant of squamous cell carcinoma (SCC), we compared the immunohistochemical expression of OSM in the tumor cells and peri- and intratumoral macrophages of 21 mature KAs, 7 regressing KAs, and 27 SCCs. An inverse correlation was identified between OSM tumor labeling and the density of OSM-labeled tumor-associated macrophages for KAs (r = -.4; P = .09). OSM tumor expression was significantly more frequent and more intense in KAs than in SCCs (95% versus 63%; P < .01). In contrast, the density of OSM-labeled macrophages was significantly higher in SCCs compared with mature KAs (7/3 high power fields versus 4/3 high power fields; P = .02). These OSM-positive macrophages were predominantly located at the advancing, infiltrative margins of both neoplasms. Regressing KAs demonstrated a decreased level of OSM tumor expression compared with mature KAs (53% versus 95%; P = .001), but there was no difference in density of OSM-labeled macrophages. Both the above differences and the overlapping patterns of OSM expression suggest that KAs are a variant of SCC where OSM, possibly as an autocrine factor, may mediate KA's overwhelming but not absolute tendency to involute.

Comparison of mitotic cyclins and cyclin-dependent kinase expression in keratoacanthoma and squamous cell carcinoma

Disruption of the cell-cycle regulation through over-expression or mutation of cyclins and cyclin-dependent kinases has been implicated in carcinogenesis. In order to determine whether keratoacanthoma (KA) is unique or a variant of squamous cell carcinoma (SCC) and whether expression of mitosis-related antigens are associated with KAs' tendency to regress, we compared the immunohistochemical expression of mitotic cyclins (cyclins A and B) and their cyclin-dependent kinase p34(cdc2) in 21 KAs, 8 regressing KAs, and 28 conventional squamous cell carcinomas. KAs showed both overlap and significant differences in expression of these mitosis-related antigens compared to SCCs. Basal and parabasal pattern of expression of cyclins A and B significantly predominated in KAs in contrast to SCCs which exhibited diffuse pattern (cyclin A 86%/cyclin B 64% vs. 25%/36%, p < 0.01). However, no differences in the highest mean level of expression in 'hot spot' loci of cyclins A and B were identified comparing KAs to SCCs (19%/12% vs. 25%/13%, p > 0.05). For the cyclin-dependent kinase p34(cdc2), no differences in pattern, distribution or mean levels of expression were found. For cyclins A and B, regressing KA showed significantly more regional tumor labeling (88%/88% vs. 57%/33%, p = 0.03) and a lower mean level of immunoreactivity (5%/4% vs. 19%/12%, p = 0.001) compared to mature KAs. These findings indicate a role for mitotic cyclins in the evolution of both SCC and KA. The overlapping patterns of expression for these mitosis-related antigens suggest that KAs represent a variant of SCC that exhibit an overwhelming but not absolute tendency to involute.

Keratoacanthomas have an immunosuppressive cytokine environment of increased IL-10 and decreased GM-CSF compared to squamous cell carcinomas

To investigate the relationship between keratoacanthoma (KA) and squamous cell carcinoma (SCC), cytokine mRNA in 12 KA and eight SCC were compared. Normal skin was also studied. Reverse transcription polymerase chain reaction (RT-PCR) was used to quantitate mRNA in each sample utilizing DNA standards. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal control, and CD3delta as an indication of the T-cell infiltrate. KAs showed a significant increase in interleukin (IL)-10, and a decrease in granulocyte macrophage colony-stimulating factor (GM-CSF) mRNA compared to SCCs. CD3delta mRNA was also increased in the KAs. There was no difference between KAs and SCCs in expression of lymphotoxin-alpha, IL-2, interferon-gamma (IFN-gamma), IL-13, transforming growth factor-beta (TGF-beta), or the pro-inflammatory cytokines IL-8 or tumour necrosis factor-alpha (TNF-alpha). These results indicate that KAs spontaneously resolve in an immunosuppressive environment. KAs grow rapidly over a period of weeks and then involute. It is possible that a suppressed immune response enables unimpeded growth and that the KA cells rapidly undergo the finite number of cell divisions of which they are capable, and then die without reaching immortality.

Immunohistochemical study of the inflammatory infiltrate associated with feline cutaneous squamous cell carcinomas and precancerous lesions (actinic keratosis)

The distribution of T lymphocytes (CD3+), B lymphocytes (CD79+), immunoglobulin-containing plasma cells (IgG, IgM and IgA), macrophages (Mac387+) and MHC Class II antigen was analysed in the inflammatory infiltrate associated with cutaneous squamous cell carcinomas (SCC) from 23 cats. Peri-tumoural skin (12 cases) and precancerous lesions of actinic keratosis (nine cases) were also evaluated for the expression of MHC Class II. The results revealed that an abundant inflammatory infiltrate was associated with the majority of SCC. This infiltrate was composed mainly of CD3+ T lymphocytes, B cells (CD79+) and IgG-bearing plasma cells, and the intensity of infiltration increased with the degree of invasiveness of the tumour. The number of CD3+ T cells and CD79+ cells was significantly increased in well-differentiated SCC compared with moderately differentiated tumours, whereas the number of IgM+, IgA+ plasma cells and Mac387+ macrophages was low or moderate and did not change significantly with histologic grade or invasiveness. MHC Class II antigen was expressed by infiltrating lymphocytes and macrophages, and by fibroblasts. A variable number of neoplastic cells (10% to 80%) in 10 SCC, and keratinocytes of basal layers in seven of nine cases of actinic keratosis also expressed MHC Class II, whereas keratinocytes of normal skin were always negative for this antigen. These results suggest that CD3+ T lymphocytes, CD79+ B cells and IgG-bearing plasma cells may participate in down-regulation of tumour growth, since these cell types were particularly numerous in well-differentiated and mildly invasive SCC, as well as in actinic keratosis. The expression of MHC Class II by neoplastic cells could enhance this local anti-tumour immune response.

Persistent keratoacanthoma: challenges in management

BACKGROUND

Keratoacanthoma is a common cutaneous neoplasm, although the persistent form is less common and often more difficult to manage. Multiple treatment approaches have been attempted with variable efficacy. Establishing the diagnosis and selecting a treatment plan for persistent keratoacanthoma is often challenging.

OBJECTIVE

Our purpose is to describe the difficulty one may encounter in the diagnosis and treatment of persistent keratoacanthoma. Hopefully, review of this clinical conundrum may facilitate the management of the reader's future patients.

METHODS

We describe a case of persistent keratoacanthoma where the diagnosis was initially elusive and the management challenging. Our thought process during each stage of diagnosis and management is described in the form of "issues" with references to the appropriate literature.

RESULTS

After several diagnostic and therapeutic interventions, successful treatment was achieved with administration of oral isotretinoin. Long-term remission continued as the dosage was tapered.

CONCLUSION

Persistent keratoacanthoma may be challenging to diagnose and manage, presenting a clinical conundrum. Careful review of the clinicopathologic presentation and an understanding of the various treatment options may result in a successful outcome.

UVA-induced immunosuppression

It has previously been demonstrated that chronic low-dose solar-simulated ultraviolet (UV) radiation can induce both local and systemic immunosuppression as well as tolerance to a topically applied hapten. Epidermal cells from UV-irradiated mice inhibit spontaneous regression of tumours indicating that UV-induced immunosuppression is likely to permit the outgrowth of developing UV-induced skin tumours. We have used a chronic low-dose UV-irradiation protocol to investigate the effects of UVA on the skin immune system of C3H/HeJ mice. Irradiation with UVA + B significantly suppressed the local and systemic primary contact sensitivity (CS) response to the hapten TNCB. Furthermore UVA + B reduced Langerhans cell (LC) and dendritic epidermal T cell (DETC) numbers in chronically UV-irradiated mice. UVA-irradiation induced local, but not systemic, immunosuppression and reduced LC (32%) but not DETC from the epidermis compared to the shaved control animals. Treatment of mice with UVA + B or UVA radiation also induced an impaired secondary CS response, and this tolerance was transferable with spleen cells. Therefore exposure of C3H/HeJ mice 5 days per week for 4 weeks with UVA can induce local immunosuppression and tolerance. One of the mechanisms by which UVA affects biological systems is production of reactive oxygen species. We have also shown that Vitamin E, an inhibitor of lipid peroxidation, prevents UV-induced immunosuppression and loss of LC. It is possible that the UVA in UV radiation induces epidermal lipid peroxidation which stimulates LC migration from the epidermis, thus contributing to UV-induced immunosuppression. Hence, inhibition of epidermal lipid peroxidation by Vitamin E may provide some protection to the skin immune system from these effects of UV.

Estimation of the volume-weighted mean nuclear volume discriminates keratoacanthoma from squamous cell carcinoma

Keratoacanthoma (KA) is a fairly common neoplasm that in the past has been considered by many to be benign. Keratoacanthoma is usually differentiated from squamous cell carcinoma (SCC) by histopathologic criteria. However, the cytologic features of KA and SCC are often similar. Hence, KA may be confused with SCC at the histopathologic level. Volume-weighted mean nuclear volume (Vv) is determined by a technique that permits an unbiased and efficient estimation of nuclear volumes in tissues without any assumptions regarding nuclear shape. In this study, the volume-weighted mean nuclear volume was determined in 18 KAs and 19 SCCs to investigate whether this stereologic approach may be of use in the differentiation of these two tumors. Vv was determined by computer-assisted image analysis (IBAS 20, Kontron, Germany) on Feulgen-stained sections employing stereologic estimation of the volume-weighted mean nuclear volume. The mean Vv of KA was 704.5 microm3 (SD +/-170.5), whereas SCC exhibited a significantly lower Vv of 533.9 microm3 (SD+/-164.9) (p = 0.006). The sensitivity and specificity of Vv for the discrimination between KA and SCC was 0.80 and 0.78, respectively. We found that KAs show a significantly larger Vv than SCCs and thus, the estimation of the volume-weighted mean nuclear volume may be regarded as a helpful tool for the differential diagnosis of KA and SCC.

Ovine cutaneous squamous cell carcinoma: immunohistochemical expression of CD3, CD4, CD8 and MHC class II antigens in the associated inflammatory infiltrate

The immunohistochemical expression of CD3, CD4, CD8 and MHC class II antigens in the cellular inflammatory infiltrate associated with early and advanced ovine squamous cell carcinomas (OSCC), as well as actinic keratosis was analyzed. The majority of the peritumoral and intratumoral lymphocytes reacted with the anti-human CD3 polyclonal antibody. The number of CD8+ T lymphocytes increased in advanced OSCC compared with that of actinic keratosis and early OSCC, whereas the number of CD4+ lymphocytes was similar in early and advanced OSCC. Tumor cells were unreactive with the anti-MHC class II antibody, but the majority of the mononuclear cellular infiltrate expressed this antigen in early and advanced tumors.

Bioactive tumour necrosis factor alpha but not granulocyte-macrophage colony-stimulating factor correlates inversely with Langerhans's cell numbers in skin tumours

Langerhans' cells (LCs) are thought to play an important role in presentation of tumour antigens for the induction of anti-tumour immunity. Epidermis overlying some transplanted murine skin tumours contains increased numbers of LCs; however, alterations in LC numbers are not related to tumour antigenicity or host immunity, suggesting that another factor(s), such as tumour-produced cytokines, influences LC density. It has been postulated that dendritic epidermal T cells (DETCs) play a role in immunosurveillance within the normal epidermis. Two cytokines which potentially alter LC numbers or function include granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-alpha). GM-CSF maintains LC viability in culture, and there are reports that it can increase LC density. There is evidence that TNF-alpha induces LC to migrate from the epidermis. In the present study, LC densities in regressor and non-regressor murine skin tumours and overlying epidermis were enumerated, and bioactive GM-CSF and TNF-alpha present in the tumours were measured. We found significantly increased epidermal LC numbers above non-regressor, but not regressor, tumours. DETC numbers were significantly increased above some tumours. Although all tumour types produced TNF-alpha, the regressors, which did not increase LC numbers, produced the most TNF-alpha. In contrast, tumour production of GM-CSF did not correlate with any pattern of alteration of LC density or tumour growth. Tumour production of neither cytokine nor tumour growth correlated with DETC numbers overlying tumours. Our results suggest that TNF-alpha may be associated with skin tumour regression and may prevent LC accumulation by tumours.

Lymphocyte counts of patients who have had skin cancer

BACKGROUND

Investigations of lymphocyte counts in patients with skin cancer have given conflicting results, possibly because homogeneous groups of patients were not studied.

OBJECTIVE

Our purpose was to measure lymphocyte counts in patients with skin cancer to determine whether any abnormalities were associated with the number of cancers removed and to determine whether a lymphocyte count could identify patients at risk of the development of large numbers of cancers.

METHODS

Apparently otherwise normal patients who had histologically confirmed skin cancers removed were studied. One group consisted of patients who had one skin cancer removed but had not had another within a minimum of 5 years. The other group consisted of patients who had had three or more skin cancers. Standard flow cytometry was used to determine the total lymphocyte count, CD4 (helper cell) count, and CD8 (cytotoxic cell) count.

RESULTS

Ninety-six patients with multiple skin cancers, and 24 with one skin cancer were studied. Only basal cell carcinomas (BCCs) were removed from 84 patients and the results from this homogeneous group were as follows: women had a higher CD4 cell count than men (p < 0.05); patients with 20 or more BCCs had a lower lymphocyte count (p < 0.01); and patients with one BCC had a higher CD4/CD8 ratio than those who had multiple BCCs (p < 0.05).

CONCLUSION

Differences were found between men and women, as well as between subgroups of patients with skin cancer. However, the range of lymphocyte counts was large and it was not possible to determine a threshold below which patients had a worse prognosis. A lymphocyte count is not a reliable way of predicting which patients will have a large number of skin cancers.

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.