Keratoacanthoma in a sub-tropical climate

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.

Features of multiple self-healing squamous epithelioma and Loeys-Dietz syndrome in a patient with a novel TGFBR1 variant

Multiple self-healing squamous epithelioma (MSSE, Ferguson-Smith disease) and Loeys-Dietz syndrome (LDS) are allelic conditions associated with pathogenic variants in the transforming growth factor beta receptor 1 gene (TGFBR1). We describe a patient with a novel missense variant in this gene: c.664G > A, p.[Gly222Arg], who clinically presents with both syndromes. The patient also has a history of gastric antral vascular ectasia, which has not been reported previously in LDS.

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.

Cutaneous lesions of the nose

Skin diseases on the nose are seen in a variety of medical disciplines. Dermatologists, otorhinolaryngologists, general practitioners and general plastic and dermatologic surgeons are regularly consulted regarding cutaneous lesions on the nose. This article is the second part of a review series dealing with cutaneous lesions on the head and face, which are frequently seen in daily practice by a dermatologic surgeon. In this review, we focus on those skin diseases on the nose where surgery or laser therapy is considered a possible treatment option or that can be surgically evaluated.

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.

Are keratoacanthomas variants of squamous cell carcinomas? A comparison of chromosomal aberrations by comparative genomic hybridization

Keratoacanthoma (KA) is a benign keratinocytic neoplasm that usually presents as a solitary nodule on sun-exposed areas, develops within 6-8 weeks and spontaneously regresses after 3-6 months. KAs share features such as infiltration and cytological atypia with squamous cell carcinomas (SCCs). Furthermore, there are reports of KAs that have metastasized, invoking the question of whether or not KA is a variant of SCC. To date no reported criteria are sensitive enough to discriminate reliably between KA and SCC, and consequently there is a clinical need for discriminating markers. We screened fresh frozen material from 132 KAs and 37 SCCs for gross chromosomal aberrations by using comparative genomic hybridization (CGH). Forty-nine KAs (37.1%) and 31 SCCs (83.7%) showed genomic aberrations, indicating a higher degree of chromosomal instability in SCCs. Gains of chromosomal material from 1p, 14q, 16q, 20q, and losses from 4p were seen significantly more frequently in SCCs compared with KAs (P-values 0.0033, 0.0198, 0.0301, 0.0017, and 0.0070), whereas loss from 9p was seen significantly more frequently in KAs (P-value 0.0434). The patterns of recurrent aberrations were also different in the two types of neoplasms, pointing to different genetic mechanisms involved in their developments.

Keratoacanthomas frequently show chromosomal aberrations as assessed by comparative genomic hybridization

Keratoacanthomas are commonly occurring benign skin lesions localized to sun-exposed areas. They typically develop rapidly and may show cellular atypia and infiltration like cutaneous squamous cell carcinomas, but they finally regress spontaneously. This benign lesion shows a high degree of genetic instability as assessed by comparative genomic hybridization, with 35.7% (25 of 70) of the analyzed lesions harboring chromosomal aberrations. The same frequency of genetic imbalance was found in lesions from immunosuppressed organ transplant recipients (36.4%, 20 of 55) and in patients with keratoacanthomas without immunosuppression (33.3%, five of 15), indicating a common pathway in both situations. Recurrent aberrations, given as a fraction of lesions with aberrations, were gains on 8q (20.0%), 1p and 9q (each 16.0%), and deletions on 3p (20.0%), 9p (20.0%), 19p (20.0%), and 19q (16.0%). Many of the most frequently appearing aberrations in keratoacanthomas were not detected in any of the 10 squamous cell carcinomas analyzed, whereas some aberrations were shared by both types of lesions. Aberrations were found in early and late stages of keratoacanthoma development, indicating a role for genetic instability in the progression as well as involution of keratoacanthomas. There were no significant correlations between cytologic atypia and genetic imbalance, or between degree of infiltration and genetic aberrations, although there was a trend for keratoacanthomas with severe atypia to have aberrations. Thus malignant phenotypic development does not appear to be driven by the detected genetic aberrations. More detailed studies of chromosomal areas with recurrent aberrations are needed for the localization of putative genes that determine the biologic behavior of keratoacanthomas, and that may distinguish them from squamous cell carcinomas.

Distal digital keratoacanthoma: two cases with a review of the literature

BACKGROUND

Distal digital keratoacanthoma (DKA) is an uncommon tumor difficult to diagnose clinically, and even histologically, with certainty.

OBJECTIVE

Our purpose is to report on two new cases and to discuss the clinical, histologic, and differential diagnosis.

METHODS

We have reviewed all well documented cases published in the literature.

RESULTS

No single diagnostic criterion is sufficiently sensitive and specific to be pathognomonic.

CONCLUSION

The diagnosis of DKA should be based on the correlation of clinical, radiological and pathologic findings, but the tumor is frequently diagnosed histologically as "squamous cell carcinoma, keratoacanthoma type" or as keratocarcinoma.

Aggressive keratoacanthoma of the eyelid: "malignant" keratoacanthoma or squamous cell carcinoma?

We report an aggressive keratoacanthoma of the upper eyelid that recurred at the site of a previously excised keratoacanthoma. The diagnosis was confirmed by biopsy. Because the surgery required would be extensive, medical therapy was tried first. The tumor was treated with intralesional injections of 5-fluorouracil and radiotherapy. Despite this therapy, the orbital computed tomogram showed tumor extension into the orbit, and an orbital exenteration was performed. Histopathology of the excised tumor was consistent with squamous cell carcinoma. We discuss the topic of malignant transformation of the keratoacanthoma.

Eruptive keratoacanthoma en plaque in an immunosuppressed patient

Immunosuppressive therapy predisposes to the development of a variety of neoplasms. A 63-year-old man developed multiple eruptive epithelial tumors 15 years after renal transplantation. The tumors included what had been diagnosed as squamous cell carcinomas, Bowen's disease, and solitary and eruptive keratoacanthomas. In addition, he developed a large plaque studded with small nodules that had the histologic features of keratoacanthoma. To our knowledge, this is the first example of acquired eruptive keratoacanthoma forming a large plaque.

Torre's syndrome: exacerbation of cutaneous manifestations with immunosuppression

Torre's syndrome is characterized by the association of sebaceous neoplasms and keratoacanthomas with visceral malignancies. We report on a patient in whom the cutaneous manifestations of Torre's syndrome dramatically increased following immunosuppression.

A solitary, exophytic, crateriform lesion on the mandibular retromolar gingiva

A solitary, intraoral keratoacanthoma discovered on the mandibular left retromolar mucosa in a 64-year-old black male is reported. This is the eighth lesion of this type reported to date. The patient had stopped smoking 5 years earlier and gave no history of an occupation involving pitch or tar. The lesion had the typical clinical and microscopic features of a keratoacanthoma. A 6-month recall examination showed no evidence of recurrence of the lesion.