Patient and Tumour Characteristics of Keratoacanthoma in a Large, Community-based Cohort Study from Queensland, Australia.

Keratoacanthomas are common keratinocyte skin tumours. However, there is little community-based data published on the clinical features of keratoacanthoma. The aim of this study was to describe the patient and tumour characteristics of keratoacanthomas, as well as their treatment patterns. Data were obtained from the QSkin Sun and Health study, a prospective cohort of 40,438 randomly sampled and consented participants aged 40-69 years in Queensland, Australia. In 2010, a baseline survey collected data, including demography, phenotype, ultraviolet radiation exposure, medical history and lifestyle. Histopathological reports of keratoacanthomas arising until 30 June 2014 were reviewed. In total, 584 participants developed 738 keratoacanthomas; 18% of participants developed multiple tumours. Common patient characteristics were male sex (58%), age ≥60 years (76%), fair skin (80%), and previous history of actinic keratoses/keratinocyte cancers (89%). Keratoacanthomas were commonly located on the legs/feet (48%), and rarely on the the head/neck (7%). Excision was the most frequently used surgical method (71%) Evidence of histopathological regression was reported in 67% of keratoacanthomas, suggesting a potential for spontan-eous resolution in a significant proportion of keratoacanthomas.

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.

Keratoacanthoma: Update on the Debate.

ABSTRACT: Keratoacanthoma (KA) is a cutaneous tumor with a biphasic pattern of growth. A rapidly growing phase is usually followed by involution. KA occurs on sun-damaged skin. There are many listed causative associations, which include some therapeutic agents. Debate continues as to whether KA is a variant of squamous carcinoma (SCC) or a separate entity. Reporting of KA versus SCC is markedly inconsistent. Reasons for inconsistency include overlapping microscopic criteria, variants of KA with more aggressive features, and possibly medicolegal concerns. Genetic studies have shown some differences between the 2 entities. Activation of apoptotic pathways has been demonstrated in KA. Genetic studies have shown a possible role of human polyomavirus 6 in the pathogenesis of at least some KAs. Given that some cases of KA have components that behave as conventional SCCs, KA can be considered as a low-grade variant of SCC with some genetic differences.

Tumor immunotherapy - A lot to learn from Keratoacanthoma.

Dysfunctionalinty and exhaustion of T cells in the tumor microenvironment is a harsh reality of anti-tumor immune response where tumor cells can escape it. A considerable effort is going on in the field of research that tries to harness the power of T cells against cancer cells to design new anti-cancer immunotherapeutic designs. All these efforts are getting a setback due to the fact that T cells become dysfunctional in tumors while expressing exhaustion markers, so it is necessary to understand from the perspective of cancer itself that what is lacking in tumor-specific T cells in tumor microenvironment so they are getting evaded. Keratoacanthoma is a compelling case of a tumor where auto-regression is happening and many molecular mechanisms can be attributed to this fact. One of the possibilities is having non-exhausting T cells and a highly conducive environment for anti-tumor immune response. In this hypothesis, I am proposing a detailed strategy to decipher this peculiar type of possible immune response in keratoacanthoma and how it can be idolized to create successful anti-cancer T cell immunotherapies.

Pseudocarcinomatous Hyperplasia, Squamous Cell Carcinoma, and Keratoacanthoma Associated to Lymphomas of the Skin and External Mucous Membranes: A Case Report and Literature Review.

Pseudocarcinomatous hyperplasia (PCH) is a benign reactive epithelial proliferation that may be associated to lymphomas of the skin or external mucous membranes. We present a case of single lesion mycosis fungoides (Woringer-Kollop's reticulosis pagetoid) associated with PCH that was initially misdiagnosed as squamous cell carcinoma (SCC) and review all PubMed-indexed previously reported cases on lymphomas of the skin or external mucous membranes associated to PCH, SCC, and keratoacanthomas. Including our own case, we collected data of 114 cases of cutaneous or mucosal lymphoproliferative disorders associated to PCH, 3 cases associated to SCC, and other 3 cases associated to keratoacanthomas. All cases were tabulated to the following parameters whenever data was available: sex, age, previous medical conditions, number of lesions (single × multiple), site of involvement (mucosa, skin or both), clinical impression, initial equivocal histopathologic diagnosis, final diagnosis, keratinocytic atypia (presence × absence), lymphocytic atypia (presence × absence), CD30-status, and treatment.

Relative Efficacy of Nonoperative Treatment of Keratoacanthomas.

BACKGROUND: Keratoacanthomas (KAs) are neoplasms of squamous epithelium which exhibit rapid growth and are often difficult to distinguish clinically from squamous cell carcinoma. Excision is the most common treatment, but in refractory cases or for KAs in cosmetically sensitive areas, nonoperative modalities may be better suited. OBJECTIVE: To compare efficacies of topical and intralesional therapies for the treatment of KAs. METHODS: A systematic literature review was performed using Medline, Ovid, and Embase. Studies looking at the efficacy of topical or intralesional treatments for KAs were included. To compare efficacy, 2-tailed t-tests were performed, with P < .05 considered statistically significant. RESULTS: Forty-one studies were identified across 5 modalities. Both topical and intralesional treatments had high KA eradication rates (92%-100%). Intralesional 5-fluorouracil led to faster KA healing times when compared to intralesional methotrexate (3.7 vs 4.6 weeks, P = .017). Similarly, topical 5-fluorouracil led to faster time to heal than topical imiquimod (3.8 vs 7.6 weeks with imiquimod, P < .0001). CONCLUSION: For nonoperative treatment of KAs, strong evidence currently exists for both topical and intralesional therapies. Decisions on which modality to use should be made on a case-by-case basis.

Treatment of Solitary Keratoacanthoma of the Nose With Intralesional Methotrexate and Review of the Literature

Keratoacathoma (KA) is a unique clinical pathological entity that is difficult to categorize. Differentiating a KA from a squamous cell carcinoma (SCC) is important for treatment implications but is often challenging. We report a patient with a solitary KA of the skin of the right ala successfully treated with intralesional (IL) injections of methotrexate (MTX). We also provide a review of the literature on IL-MTX as a treatment modality for KA. J Drugs Dermatol. 2019;18(7):693-696.

[Keratoacanthomas on recent tattoos: Two cases]. / Kératoacanthomes sur tatouages récents : deux cas.

BACKGROUND: Increasing numbers of reports of rapidly arising, isolated or eruptive keratoacanthomas (KA) and squamous cell carcinomas (CSC) on the red part of tattoos tend to suggest a non-fortuitous link with the procedure. We report herein two different presentations of KAs on tattoos: one patient with multiple eruptive KAs on sun-exposed areas of a recent red tattoo and another with a solitary lesion on a recent tattoo. We discuss the issues related to the distinction between KAs and CSCs in this particular context. PATIENTS AND METHODS: Case No. 1: A 55-year-old heavily tattooed man presented multiple round keratotic verrucous-like lesions restricted to a red tattoo. The tattoo had been performed by a professional tattooist in summer 2016, a week before the onset of the symptoms. The patient did not protect a part of his tattoo from sun-exposure during the healing phase and lesions developed only on the sun-exposed tattooed parts. In January 2017, he consulted with about ten lesions. The histologic study by shaving of a lesion militated in favor of a CSC, KA type. The physical examination was unremarkable. He had no previous history of skin cancer. Two weeks later, most of the lesions regressed spontaneously. Based on the clinical history and progression of the lesions, a diagnosis was made of eruptive KA on a red tattoo. Residual lesions were treated by cryotherapy or excision. Case No. 2: A 72-year-old woman developed a 1-cm painful dome-shaped nodule with a central crust three weeks after tattooing. Full excision confirmed the diagnosis of KA. DISCUSSION: To date, we have found 31 case reports and series (17 men, median age: 50.5 years) of KA and CSC on tattoos. Lesions usually develop rapidly after completion of the tattoo, after between one week and several months. Exceptional cases have been described in old tattoos. Red tattoo ink is most commonly the culprit. The main difficulty lies in distinguishing between KA and CSC. Nowadays pathologists agree that a KA should be considered as a variant of CSC. Eruptive forms of KA present a peculiar situation. They may sometimes be inherited, and KA on recent traumatized areas or drug-induced have been described. Like other authors, we believe that cases of CSC on red tattoos belong rather to the KA type. The physiopathogenesis of tattoo-associated eruptive KA and CSC is not clearly understood, but could be multifactorial, involving: the trauma induced by tattooing, local inflammatory reaction, a component of the red ink, external factors such UV exposure, and a possible genetic predisposition. Rapidly arising KA and eruptive KA on top of recent (red) tattoos are not fortuitous. The lesions should be excised and the patient monitored. Additional studies on tumor specimens are warranted to identify the possible causative agents in tattoo ink that may be responsible for such reactions.

Research gaps in the management and prevention of cutaneous squamous cell carcinoma in organ transplant recipients.

Although tremendous progress has been made in recent years in skin cancer care for organ transplant recipients, significant gaps remain in data-driven clinical guidelines, particularly for the treatment and prevention of cutaneous squamous cell carcinoma (cSCC), the most common malignancy among this population. In this review, we aim to summarize current knowledge around the management of cSCC and highlight the most significant gaps in knowledge that continue to pose challenges in the delivery of skin cancer care for organ transplant recipients. We suggest future directions for research that will bridge existing gaps and establish evidence-driven guidelines for primary prevention, screening and treatment of cSCC in this high-risk patient population.

Eruptive Keratoacanthomas Associated With Pembrolizumab Therapy.

Importance: To our knowledge, there have been no previous reports of eruptive keratoacanthomas (KAs) in patients receiving pembrolizumab. Objective: To report the cases of 3 consecutive patients with pembrolizumab-induced eruptive KAs and their management. Design, Setting, and Participants: Case report study of 3 patients from 2 centers with pembrolizumab-treated cancer who all developed eruptive KAs. Interventions: All 3 patients had AK treatment with clobetasol ointment and intralesional triamcinolone; 2 patients also underwent open superficial cryosurgery. Results: Three consecutive patients with cancer, 2 men and 1 woman (median age, 83 years; range 77-91 years), experienced pembrolizumab-associated eruptive KAs. All patients presented with a sudden onset of multiple lesions on sun-exposed areas of their extremities after a median of 13 months (range, 4-18 months) of pembrolizumab therapy. On lesional biopsy, a lichenoid infiltrate was observed in the underlying dermis, predominantly composed of CD3+ T cells, scattered CD20+ B cells, and relatively few PD-1+ (programmed cell death 1-positive) T cells, an immunophenotypic pattern also observed in other cases of anti-PD-1-induced lichenoid dermatitis. Patients were treated with clobetasol ointment and intralesional triamcinolone, alone or in combination with open superficial cryosurgery. All KAs resolved in all patients, and no new lesions occurred during close follow-up. Pembrolizumab treatment was continued without disruption in all 3 cases, and all patients had complete responses of their primary cancers. Conclusions and Relevance: Pembrolizumab is used in advanced melanoma, advanced non-small-cell lung cancer, and in head and neck cancer. A variety of dermatologic immune-related adverse events including maculopapular eruption, lichenoid reactions, pruritus, and vitiligo have been described. This case series demonstrates that pembrolizumab therapy may also be associated with eruptive KAs with characteristic dermal inflammation, which improved with corticosteroid treatment (topical and intralesional) alone or in combination with cryosurgery, allowing patients to continue therapy with pembrolizumab.

Keratoacanthoma formation after skin grafting: A brief report and pathophysiological hypothesis.

Keratoacanthoma formation after skin grafting is rare. We report the third case in the literature of multiple keratoacanthomas developed at both split-thickness skin graft donor and recipient sites. We provide possible explanations for this poorly understood phenomenon and highlight its implications on treatment options.