This Corrigendum relates to the following article: https://doi.org/10.2340/actadv.v104.13381.

In December 2020, a major vaccination program against COVID-19 commenced in Europe with vaccines such as Pfizer\'s mRNABNT162b2 (Comirnaty®). Subsequent reports of immediate and delayed skin reactions emerged. This study presents a case of a 64-year-old male who developed multiple keratoacanthomas approximately two weeks after receiving a second booster dose of the Pfizer vaccine. The patient, who had significant medical history of hypertension and diabetes, presented with erythematous, crateriform lesions on his limbs. A physical examination and histopathological analysis confirmed the diagnosis of Generalized Eruptive Keratoacanthoma (GEKA). Treatment involved cemiplimab I.v. 350 mg administered every three weeks. Within two months, the patient showed significant improvement, with the disappearance of all lesions. Dermoscopy and histopathological exams supported the GEKA diagnosis, which is a rare variant of multiple keratoacanthomas. This case suggests a potential immune-mediated mechanism triggered by the COVID-19 vaccine, leading to the rapid development of keratoacanthomas. Treatment with cemiplimab showed promise, highlighting the potential of immune checkpoint inhibitors in managing multiple keratoacanthomas. Further research is needed to explore the efficacy and safety of such treatments.

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When the dermoscopy of squamous cell carcinoma and its precursors we differentiate among keratin-related, vascular, and pigment-related criteria. Non-pigmented actinic keratoses are characterized by the \"strawberry pattern\". Pigmented actinic keratosis shows a significant dermatoscopic overlap with lentigo maligna, but the presence of pigmented scales, erythema, and prominent follicles favors its diagnosis. Bowen\'s disease is characterized by clustered glomerular vessels, white-yellowish scales, and brown or grey dots arranged in lines in its pigmented variant. Finally, dermoscopy allows us to detect invasive squamous cell carcinoma in its early stages and differentiate it from its precursors. Furthermore, its presentation may vary depending on the degree of differentiation, with keratin-associated criteria predominating in well-differentiated tumors, while an atypical vascular pattern will predominate in poorly differentiated tumors.

BACKGROUND: Intralesional methotrexate injection (IL-MTX) is an appropriate strategy for treating epithelial crateriform tumors (ECTs) when surgical excision can result in functional or cosmetic defects; however, not all ECTs are responsive to this treatment.
OBJECTIVE: This study aimed to evaluate the effectiveness of IL-MTX for ECTs and to determine the differences in clinical response according to the pathological features.
METHODS: The medical records of patients treated with IL-MTX for their ECTs were retrospectively reviewed. Effectiveness was evaluated in terms of size reduction and flattening.
RESULTS: Twenty-five cases of ECTs with biopsy were included in this study. Eight cases of keratoacanthoma (KA) and 15 cases of squamous cell carcinoma (SCC) were identified, but 2 cases could not be clearly distinguished. Seventeen patients (68%) showed a response after injection, and response rate in KA and SCC were 75% (6/8) and 60% (9/15), respectively. Nine patients showed complete resolution with IL-MTX. Patients received 3 injections, and regression was observed in 7.56 weeks after the first injection. According to histopathological results, patients with KA and SCC received 2 and 3.33 injections, respectively, and complete resolution was observed after 7 and 7.67 weeks, respectively.
CONCLUSIONS: IL-MTX is safe and effective, and could be considered as a useful non-surgical treatment option for ECTs. Both KA and crateriform SCC showed good response; However, KA showed a better response.

Tattooing, the introduction of exogenous pigments into the skin, has a rich history spanning thousands of years, with cultural, cosmetic, and medical significance. With the increasing prevalence of tattoos, understanding their potential complications and contraindications is of growing importance. The most common complications are hypersensitivity reactions, which may vary in morphology and timing. Infectious complications are often due to inadequate aseptic and hygienic practices during the tattooing process or healing period. Tattoo pigment can present diagnostic challenges, affecting cancer diagnosis and imaging. This CME article explores the history, cultural significance, epidemiology, chemistry, technique, contraindications, and complications of tattoos. Appreciating these factors can help individuals considering tattoos understand the safety and potential risks of their body art, and provide physicians with a thorough understanding of tattooing if consulted.

UNASSIGNED: Tattooing is a widespread practice and has increased in popularity over time. Many lesions have been described in relation to tattoos, including malignant tumors.
UNASSIGNED: The primary goal of this review is to determine whether the frequency of published cases of skin cancers within tattoos has been increasing over time.
UNASSIGNED: Our review is in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and reporting criteria. The databases MEDLINE via PubMed, Embase via Elsevier, and Scopus via Elsevier were searched from inception to February 23, 2023. No data or publication date limits were imposed.
UNASSIGNED: Our review identified 160 cases of cutaneous tumors arising within tattoos. An increase in published cases over time was observed. Most reported tumors developed within red tattoo pigment (36.9%), with the largest contribution by squamous cell carcinoma and keratoacanthoma lesions.
UNASSIGNED: There was a lack of consistency of information in published case reports which limited the scope of our analysis. Small sample size was also a limitation of this review.
UNASSIGNED: With the increased popularity of tattoos, it is helpful to continue reporting cases of cutaneous malignancies within tattoos. Awareness of the frequency and severity of tumors within tattoos may be communicated to the public.

BACKGROUND: Keratoacanthoma (KA) is a benign neoplasm that affects mainly photodamaged skin. It is locally destructive and may rarely spread. Surgery is not always suitable and usually disfiguring. Thus, non-operative modalities represent good alternatives.
OBJECTIVE: To assess and compare the efficacy of intralesional methotrexate (MTX) and 5-flurouracil (5-FU) in the treatment of KA.
METHODS: Randomized controlled trial included 20 patients with biopsy proven KA divided into 2 equal groups; group (A) received intralesional MTX, 25 mg/ml and group (B) received intralesional 5-FU, 50 mg/ml every 2 weeks till complete clearance or for a maximum 5 sessions.
RESULTS: In the MTX group, complete clearance was observed in 7 patients (70%) compared to 8 patients (80%) in the 5- FU group with no statistically significant difference. However, the median number of injections needed to achieve complete response in the MTX group was 3 sessions versus only 2 sessions in the 5-FU group.
CONCLUSIONS: the small sample size due to the relatively low incidence of KAs in our population.
CONCLUSIONS: Intralesional therapy is a good alternative to surgery in selected cases of KA. Both drugs showed comparable efficacy, but 5-FU may give faster results, hence increasing patient satisfaction and compliance.

To study mechanisms driving/inhibiting skin carcinogenesis, stage-specific expression of 14-3-3σ (Stratifin) was analyzed in skin carcinogenesis driven by activated rasHa/fos expression (HK1.ras/fos) and ablation of PTEN-mediated AKT regulation (K14.creP/Δ5PTENflx/flx). Consistent with 14-3-3σ roles in epidermal differentiation, HK1.ras hyperplasia and papillomas displayed elevated 14-3-3σ expression in supra-basal keratinocytes, paralleled by supra-basal p-MDM2166 activation and sporadic p-AKT473 expression. In bi-genic HK1.fos/Δ5PTENflx/flx hyperplasia, basal-layer 14-3-3σ expression appeared, and alongside p53/p21, was associated with keratinocyte differentiation and keratoacanthoma etiology. Tri-genic HK1.ras/fos-Δ5PTENflx/flx hyperplasia/papillomas initially displayed increased basal-layer 14-3-3σ, suggesting attempts to maintain supra-basal p-MDM2166 and protect basal-layer p53. However, HK1.ras/fos-Δ5PTENflx/flx papillomas exhibited increasing basal-layer p-MDM2166 activation that reduced p53, which coincided with malignant conversion. Despite p53 loss, 14-3-3σ expression persisted in well-differentiated squamous cell carcinomas (wdSCCs) and alongside elevated p21, limited malignant progression via inhibiting p-AKT1473 expression; until 14-3-3σ/p21 loss facilitated progression to aggressive SCC exhibiting uniform p-AKT1473. Analysis of TPA-promoted HK1.ras-Δ5PTENflx/flx mouse skin, demonstrated early loss of 14-3-3σ/p53/p21 in hyperplasia and papillomas, with increased p-MDM2166/p-AKT1473 that resulted in rapid malignant conversion and progression to poorly differentiated SCC. In 2D/3D cultures, membranous 14-3-3σ expression observed in normal HaCaT and SP1ras61 papilloma keratinocytes was unexpectedly detected in malignant T52ras61/v-fos SCC cells cultured in monolayers, but not invasive 3D-cells. Collectively, these data suggest 14-3-3σ/Stratifin exerts suppressive roles in papillomatogenesis via MDM2/p53-dependent mechanisms; while persistent p53-independent expression in early wdSCC may involve p21-mediated AKT1 inhibition to limit malignant progression.

OBJECTIVE: To determine variations in allele and genotype frequencies between keratoacanthoma (KA) and common warts (CW), compared with the control group, in three single nucleotide polymorphisms (SNPs) within the TLR2, TLR3, and TLR9 genes.
METHODS: This case-control study involved samples from 161 patients with KA, 152 patients with CW, and 469 controls. DNA was isolated from formalin-fixed paraffin-embedded tissue sections. Three SNPs - rs4696480 in TLR2, rs7657186 in TLR9, and rs35213 in TLR3 - were genotyped with TaqMan Genotyping Assays on the 7500 Real-Time PCR System.
RESULTS: TLR2 rs4696480 and TLR3 rs7657186 were significantly overrepresented in KA and CW compared with controls (P<0.001). The association was stronger for CW than for KA, as evidenced by higher frequencies of the A allele and AA genotype for rs4696480. Both KA and CW patients had higher frequencies of the G allele and GG genotype for rs7657186 than controls. rs7657186 was moderately associated with KA and CW, with the G allele and GG genotype being more prevalent in CW cases, where no AA homozygotes were found.
CONCLUSIONS: Genetic variants in TLR2 (rs4696480) and TLR3 (rs7657186) genes may affect KA and CW development, influencing immune responses and susceptibility to these skin lesions. Further research is required to elucidate TLR expression patterns and their role in KA development.