Keratoacanthoma: the Australian experience

Radiotherapy for keratoacanthoma of facial skin: A case report and review of literature

Background

Keratoacanthoma (KA) is a benign tumor that arises from the infundibulum of hair follicles. However, some researchers believe that KA is a subtype of squamous cell carcinoma (SCC) or a borderline tumor. There are two types of KA: single-type and multiple-type. Surgical resection is the first-line treatment for KA. The treatment options for patients with large lesions who are not surgical candidates are limited. We present a case of single-type KA patients with basic diseases and large lesions that were untreatable surgically, but the lesions essentially disappeared after radiotherapy. No recurrences were discovered during the two-year follow-up.

Case Description

A 62-year-old male patient was admitted to the dermatology department of our hospital in June 2020 due to the discovery of a red papule on the right face two months prior, with occasional itching, which increased gradually. Pathological examination confirmed the diagnosis of KA. Due to the large lesions and underlying diseases, he was transferred to our radiotherapy department for radiotherapy after consultation. Since the surface of the lesion is uneven and close to the corner of the eye, we adopted intensity modulated radiation therapy (IMRT) at the beginning of radiotherapy. Following the reduction of the lesion, superficial electron beam and added a bolus with thickness of 5mm on the surface of the lesion was continued. The target dose: 42Gy/21 fractions (6MV X-ray, 22Gy; 2Gy/fraction; a total of 11 fractions, 6MeV electron beam, 20Gy; 2Gy/fraction; a total of 10 fractions). By the end of radiotherapy, the patient's facial tumor was dry and subsided. The facial tumor subsided significantly two years after radiotherapy, and the damaged skin on the face recovered to a flat shape.

Conclusions

The treatment experience of this case shows that IMRT combined with superficial electron beam radiotherapy may be an effective treatment for single-type KA patients with basic diseases and large lesions that are not suitable for surgery, and it is worth further study.

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.

Assessment of Incidence Rate and Risk Factors for Keratoacanthoma Among Residents of Queensland, Australia

Importance

Keratoacanthoma (KA) is a common and generally benign keratinocyte skin tumor. Reports of the incidence rates of KA are scant. In addition, the risk factors for KA are not well understood, although associations with UV radiation exposure and older age have been described.

Objective

To investigate the incidence rate of KA and the risk factors for developing KA.

Design, Setting, and Participants

The study included data from 40 438 of 193 344 randomly selected residents of Queensland, Australia, who participated in the QSkin Sun and Health (QSkin) prospective population-based cohort study. All participants completed a baseline survey between 2010 and 2011 and were ages 40 to 69 years at baseline. Histopathologic reports of KA were prospectively collected until June 30, 2014, through data linkage with pathologic records. Cox proportional hazards models were used to identify risk factors associated with KA while controlling for potential confounding variables. Data were analyzed from January 2 to April 8, 2020.

Exposures

Demographic characteristics, phenotypes, UV radiation exposure, medical history, and lifestyle.

Results

Among 40 438 participants (mean [SD] age, 56 [8] years; 18 240 men [45.1%]), 596 individuals (mean [SD] age, 62 [6] years; 349 men [58.6%]) developed 776 KA tumors during a median follow-up period of 3.0 years (interquartile range, 2.8-3.3 years). The person-based age-standardized incidence rate for KA in the age-restricted cohort was 409 individuals per 100 000 person-years (based on the 2001 Australian population). Risk factors after adjustment for potential confounders were older age (age ≥60 years vs age <50 years; hazard ratio [HR], 6.38; 95% CI, 4.65-8.75), male sex (HR, 1.56; 95% CI, 1.33-1.84), fair skin (vs olive, dark, or black skin; HR, 3.42; 95% CI, 1.66-7.04), inability to tan (vs ability to tan deeply; HR, 1.69; 95% CI, 1.19-2.40), previous excisions of keratinocyte cancers (ever had an excision vs never had an excision; HR, 6.28; 95% CI, 5.03-7.83), current smoking (vs never smoking, HR, 2.02; 95% CI, 1.59-2.57), and high alcohol use (≥14 alcoholic drinks per week vs no alcoholic drinks per week; HR, 1.42; 95% CI, 1.09-1.86).

Conclusions and Relevance

This is, to date, the first large prospective population-based study to report the incidence rate and risk factors for KA. The high person-based incidence rate (409 individuals per 100 000 person-years) highlights the substantial burden of KA in Queensland, Australia. Furthermore, the study's findings suggest that older age (≥60 years), male sex, UV radiation-sensitive phenotypes, indications of high sun exposure (eg, previous keratinocyte cancer excisions), smoking, and high alcohol use are independent risk factors for the development of KA.

Cutaneous Squamous Cell Carcinoma: Review of the Eighth Edition of the American Joint Committee on Cancer Staging Guidelines, Prognostic Factors, and Histopathologic Variants

Cutaneous squamous cell carcinoma is the second most common form of nonmelanoma skin cancer after basal cell carcinoma and accounts for the majority of nonmelanoma skin cancer-related deaths. In 2017, the American Joint Committee on Cancer revised the staging guidelines of cutaneous squamous cell carcinoma to reflect recent evidence concerning high-risk clinicopathologic features. This update reviews the literature on prognostic features and staging, including the eighth edition of the American Joint Committee on Cancer Staging Manual. A wide range of histopathologic variants of cutaneous squamous cell carcinoma exists, several of which are associated with aggressive behavior. A review of cutaneous squamous cell carcinoma variants, emphasizing diagnostic pitfalls, immuhistochemical findings and prognostic significance, is included. Of note, the eighth edition of the American Joint Committee on Cancer Staging Manual refers to squamous cell carcinoma of the head and neck only.

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.

Keratoacanthoma: hyperplasia, benign neoplasm, or a type of squamous cell carcinoma?

Keratoacanthomas are common self limited squamous proliferations. They have been considered a benign neoplasm with involution and complete resolution within few months. Although considered the prototypical example of cutaneous pseudomalignancy, some believe that these tumors are squamous cell carcinomas and through the years there have been sporadic reports of "metastasizing keratoacanthomas". The question has been raised as to whether keratoacanthoma is an unreliable histological diagnosis or these tumors have a latent, albeit rare, malignant potential. To date, just a handful of "metastasizing keratoacanthomas" have been reported. Since a benign lesion is incapable of metastasis, some other explanation must be considered; the most likely one being a misdiagnosis. While it is clear that in some cases, the histological and cytological features of squamous cell carcinoma and keratoacanthoma are difficult to distinguish by current techniques, these occasional limitations in diagnosis do not make keratoacanthomas a carcinoma. We believe the evidence supports that keratoacanthomas are benign squamous proliferations. The diagnosis can be made with confidence in appropriate biopsies and using well established clinicopathological criteria.

Keratoacanthoma of the inferior lip: review and report of case with spontaneous regression

Keratoacanthoma (KA) is a self-limited benign epithelial proliferative lesion that eventually presents with very similar clinical features to squamous cell carcinoma. Many KA appear in the vermilion border of the lips and therefore dental professionals must be familiar of the disease. This article reports the case of a 40-year-old female patient presenting with an exophytic ulcerative tumor in her lower lip that resolved after incisional biopsy. Photographic documentation of the case is presented and topics that are relevant to the clinical management of the disease are addressed.

Periocular keratoacanthoma: can we always rely on the clinical diagnosis?

AIM

To present a series of patients with a clinical diagnosis of periocular keratoacanthoma and assess the incidence of histologically proven invasive squamous cell carcinoma (SCC).

METHODS

This retrospective case series included all patients with periocular tumours seen in the authors' unit between 1996 and 2004, and who were initially diagnosed with keratoacanthoma based on the clinical presentation.

RESULTS

Twelve patients (eight males, four females) were clinically diagnosed with keratoacanthoma. The final histological diagnosis revealed two cases (16.7%) of invasive SCC, and 10 cases (83.3%) of keratoacanthoma. The lower lid was most commonly involved in cases of keratoacanthoma (50.0%). Six patients (60.0%) underwent Mohs surgery, and four (40.0%) were treated with excision under frozen section control. There were no cases of recurrence during a mean follow up period of 21 (SD 13) months.

CONCLUSION

Although the clinical presentation of periocular keratoacanthoma is usually characteristic, a significant percentage of patients will prove to have invasive SCC. Complete excision with margin control offers a definitive diagnosis, as well as tissue conservation and a low recurrence rate.

Vulval Keratoacanthoma: a case report

BACKGROUND

Vulval Keratoacanthoma (KA) is very rare and its differential diagnosis from the commonly occurring Vulval Squamous Cell Carcinoma (SCC) is important to avoid overtreatment.

CASE

A case of Vulval KA in a 79-year-old lady is reported. She presented with a 9-mm firm raised lesion on the antero-lateral left side of the clitoris of a few months' duration with no associated symptoms. The lesion was resected with clear margins and the excision site was well healed at her appointment 4 weeks later.

CONCLUSION

We share our experience reporting the fifth case of a vulval KA in the world literature. Consideration to the occurrence of vulval KA is important to avoid both an erroneous diagnosis of vulval SCC and the associated consequences of radical surgery.

Combined 5-Fluorouracil and Er:YAG Laser Treatment in a Case of Recurrent Giant Keratoacanthoma of the Lower Leg

BACKGROUND

Keratoacanthomas are fast-growing squamous tumors, which usually show spontaneous regression. The development of giant variants with an aggressive behavior has been described. Although surgical excision remains the treatment of choice for very large keratoacanthomas, other therapeutic options including laser surgery and topical chemotherapy may be superior in special situations.

OBJECTIVE

The objective was to evaluate the efficacy of Er:YAG laser surgery combined with topical 5-fluorouracil treatment in a case of recurrent giant keratoacanthoma.

METHODS

A 64-year-old woman presented for evaluation and treatment of recurrent tumors in her face and extremities. Despite repeated invasive surgical removal of these lesions, recurrence of fast-growing giant keratoacanthomas developed in the pretibial region of her left lower leg. Owing to recurrence after conventional surgery and the tumor size, a novel treatment method using ablative Er:YAG laser combined with topical 5-fluorouracil was performed.

RESULTS

After four treatments with excellent patient compliance, histologic analysis of punch biopsies revealed tumor-free ulcerations. Complete epithelization was obtained after 9 weeks. Six months after the treatment, no recurrence was observed.

CONCLUSION

The combined use of ablative Er:YAG laser and topical 5-fluorouracil chemotherapy may be considered as an effective treatment option in cases of giant keratoacanthoma when conventional surgery is not indicated.

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.

Periocular keratoacanthoma: clinical features, pathology, and management

PURPOSE

To review the clinical features and results of surgical treatment of keratoacanthoma of the eyelids.

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Ten patients.

METHODS

Chart review of all eyelid keratoacanthomas treated between 1992 and 2001.

MAIN OUTCOME MEASURES

Adequate excision, recurrence rate, and complications.

RESULTS

Patient ages ranged from 27 to 78 years, with a mean age of 59 years. Six patients were male and four were female. The lesion was found on the lower lid in five patients, upper lid in two, medial canthus in two, and lateral canthus in one. The maximum diameter of the lesion varied from 2 to 25 mm, with a mean of 7.2 mm. All lesions were treated by surgical excision, with frozen-section control of margins in five cases. All lesions were excised completely with clear resection margins, and there were no cases of recurrence. The only complication was a minor wound infection in one patient. Mean follow-up was 34.5 months.

CONCLUSIONS

Because of the aggressive nature and uncertain relationship to squamous cell carcinoma, we recommend excision of periocular keratoacanthoma. Surgical excision of eyelid keratoacanthoma provides good results and a very low risk of recurrence. Frozen-section control of margins should be used in selected cases to ensure complete excision.