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.

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.

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.

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.

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.

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.

[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.

Neglect leads to extremes: maggots and malignancy in a case of discoid lupus erythematosus.

Discoid lupus erythematosus (DLE) is a chronic form of cutaneous lupus erythematosus that runs an indolent course. The rare complications of DLE include scarring, mutilation, non-healing ulceration, cicatricial alopecia and malignancy. DLE progresses to systemic lupus erythematosus (SLE) in around 5% of localized cases and 22% of generalized cases. We report a case of DLE, presenting with a six-month history of ulcerated fungating plaques and small crusted nodules superimposed on DLE plaques over both the forearms. Two weeks prior to the presentation, maggots were also noticed on these plaques. Skin biopsies from these lesions were suggestive of squamous cell carcinoma (SCC) and keratoacanthoma. A wide surgical excision of the tumor followed by partial split-thickness skin grafting was performed with complete healing of the lesions. No recurrence has been noted 18 months from follow-up.

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.

Keratoacanthomas arising in association with prurigo nodules in pruritic, actinically damaged skin.

BACKGROUND: There is no known association between the development of keratoacanthomas and prurigo nodules. OBJECTIVE: We report a case series of 7 patients with a long-standing history of actinic damage, pruritus, and prurigo nodularis who developed widespread keratoacanthomas within the same affected area. METHODS: This was a retrospective case series assessing the clinical characteristics of patients with multiple keratoacanthomas arising in association with prurigo nodules. RESULTS: All 7 patients were elderly Caucasian women (mean age 79 ± 3.7 years) with actinically damaged skin and a long-standing history of widespread pruritus and prurigo nodules. All patients had histologically confirmed keratoacanthomas, or squamous cell carcinomas with the clinical appearance of a keratoacanthoma, that developed within the field of prurigo nodules. All 7 patients had a clinical response to acitretin with a decrease in the number of lesions. Four patients had an associated eczematous dermatitis and were also treated with cyclosporine with improvement in pruritus and prurigo nodules and no increase in keratoacanthomas. LIMITATIONS: The retrospective design and small number of patients are limitations to this study. CONCLUSION: Our case series represents a distinct subset of elderly individuals with extensive actinic damage who we believe are predisposed to developing both prurigo nodules and keratoacanthomas.