A clinical and biological review of keratoacanthoma

Vulvar keratoacanthoma may be a malignant precursor: A case report and literature review

Background

Keratoacanthoma is a relatively rare skin tumor, with vulvar keratoacanthoma being even more uncommon. Although the majority of keratoacanthomas exhibit a benign course, a subset of cases may show features of malignant potential, such as marginal invasion and recurrence.

Case

An 82-year-old female presented with a rapidly growing exophytic lesion on the left vulva, measuring 1.5 cm in diameter, accompanied by pruritus. The lesion had been present for two months. The patient underwent vulvar mass excision, and postoperative pathology revealed squamous cell hyperplasia with glassy cytoplasm and no significant cellular atypia. The surgical margins were clear. Three years later, the tumor recurred with disordered growth.

Conclusion

In terms of histological and clinical presentation, keratoacanthoma may overlap with classical well-differentiated squamous cell carcinoma. In rare cases, certain atypical keratoacanthomas may exhibit intravascular and perineural invasion, along with lymph node metastasis. By sharing our treatment experience of a patient with recurrent vulvar keratoacanthoma following surgery, we aim to provide a cautionary perspective for the clinical management of such cases.

Pediatric Eyelid Cutaneous Horns: A Case Series and Literature Review

PURPOSE

To describe the clinical and histopathologic features of pediatric eyelid cutaneous horns.

DESIGN

Retrospective observational case series and review of literature.

SUBJECTS

Five pediatric patients with eyelid cutaneous horns.

METHODS

Five cases with eyelid cutaneous horns were retrospectively identified using departmental databases. Patients' records were analyzed for demographic data, clinical appearance, histologic findings, and clinical course. An excisional biopsy of the lesion was performed in 3 patients. The remaining 2 patients were managed conservatively.

MAIN OUTCOME MEASURES

Clinical outcome and histopathologic evaluation with emphasis on excluding malignancy.

RESULTS

All 5 cutaneous horn lesions resolved surgically or conservatively. The average age at presentation was 6.6 years (range 5-11 years). Clinically, 4 lesions were preceded by a hordeolum or chalazion and all excised lesions had benign features on histologic examination. Mitotic figures or atypia were not observed. None of the patients developed recurrence during the follow-up period ranging from 1 to 96 months. Five previous reports of five cases were found on review of the literature. Our case series doubles this number to support the benign nature of these lesions in children.

CONCLUSIONS

Pediatric eyelid cutaneous horns are closely related to eyelid margin inflammatory disease and appear to follow a benign course. This contrasts with the adult population where cutaneous horns are frequently associated with neoplasia.

Multiple Keratoacanthomas Associated with Genetic Syndromes: Narrative Review and Proposal of a Diagnostic Algorithm

Keratoacanthoma (KA) is a relatively common, fast-growing epithelial tumour, with characteristic behaviour and clinical variability. Although it appears as a solitary lesion in a majority of cases, multiple KAs do occur, secondary to skin exposure to ultraviolet radiation, chemical carcinogens or certain medications, but may also be associated with various genetic syndromes. Thus, multiple KAs may serve as an early clinical alarm sign. Prompt diagnosis of the underlying cause and identification of the mechanism of development are critical for the secondary prevention of associated organ disorders or neoplasias, the improvement of patient quality of life and familial counselling. Although research in this field has seen important progress in the last few years, there are still many pathogenic processes that have not been elucidated. Additionally, the literature on this topic is limited to individual case reports and small case series, making it difficult for clinicians to parse available data and select the essential information. Therefore, this work aims to review current knowledge, summarizing existing studies, with focus on multiple KAs associated with genetic syndromes, and proposes a diagnostic algorithm for these rare cases to help guide clinicians in their practice. Lastly, we aim to highlight the main gaps in understanding the underlying mechanisms and suggest further research avenues.

Ultrasound Characteristics of Keratoacanthoma: Differentiation From Well-Differentiated Cutaneous Squamous Cell Carcinoma

OBJECTIVE

This study aims to describe the ultrasound characteristics of keratoacanthoma (KA), providing valuable insights for non-invasive diagnosis and differentiation from well-differentiated cutaneous squamous cell carcinoma (wcSCC).

METHODS

Ultrasound characteristics of 16 KA and 13 wcSCC conformed by surgical pathology were retrospective analyzed.

RESULTS

KA patients were younger (mean age 63.13 years) compared with wcSCC patients (mean age 76.23 years). Ultrasound characteristics revealed that KA lesions were generally smaller, more frequently domed-shaped (87.50 vs 38.46%), exophytic (93.75 vs 30.77%), and well-defined (93.75 vs 53.85%) compared with wcSCC. Both lesion types predominantly showed hypoechoic internal echoes and inhomogeneous echotexture. The prevalence of hyperechoic superficial area was notably high in both groups (93.75 vs 84.62%), precluding the reliable use of this feature as a discriminatory marker between these two distinct neoplastic entities. KA lesions were mostly confined to the epidermis and superficial dermis (87.50%), while wcSCC cases frequently infiltrated into the subcutaneous fat layer (84.62%). Color Doppler imaging demonstrated higher vascularity in wcSCC lesions, with 61.5% showing Grade 3 flow, compared with KA lesions, where 62.5% exhibited Grade 2 flow.

CONCLUSIONS

High-frequency ultrasound reveals distinct ultrasound characteristics differentiating KA from wcSCC, offering a promising non-invasive tool for preliminary diagnosis and treatment planning.

Keratoacanthoma versus Squamous-Cell Carcinoma: Histopathological Features and Molecular Markers

Considerable controversy exists within the field of dermatopathology in differentiating keratoacanthoma (KA) from squamous-cell carcinoma (SCC). KAs are rapidly growing, benign squamous tumors that are typically well differentiated. This controversy stems from the diverging perspectives on the management, classification, and diagnosis of each entity. Many believe that KAs are benign neoplasms in which intervention may be unnecessary since they are self-limiting and resolve on their own. On the other hand, SCC needs to be treated, as it carries significant morbidity and mortality risks. Early diagnosis and treatment are vital to prevent serious consequences of SCC. Nevertheless, KAs may resemble SCC grossly and microscopically. Various ancillary tests, including immunohistochemical (IHC) staining, have been proposed to differentiate between these entities, though mixed patterns of expression can limit the diagnostic utility of these techniques. Research into this topic is ongoing, with newer genetic and molecular findings illuminating the previously difficult-to-understand aspects of KA and increasing our understanding of this entity. In this review, KA and SCC will be compared along the lines of histological features, genetic, immune, and molecular markers, differential diagnosis, and management to clarify the similarities, differences, and misconceptions about both entities.

Spontaneous resolution of eruptive papules following ablative laser resurfacing-Case report and review of laser-associated eruptive keratoacanthomas

BACKGROUND

Keratoacanthomas (KAs) following laser treatment are a rare, but well-described entity.

AIM

Herein, we describe a case of eruptive keratoacanthoma (KA) following laser resurfacing treatment and aim to better characterize laser-associated KAs.

METHODS

A literature search was performed on PubMed reviewing laser-associated KAs including various characteristics: epidemiology, history of skin cancer, location, and number, type of laser, as well as the management and outcome.

RESULTS

Fractional ablative was the most common type of laser triggering KAs, and most cases presented within the first month following treatment. The majority of cases of laser-induced KA had a prior history of a malignant or premalignant skin neoplasm. Laser-induced KAs were treated using modalities similar to KAs arising in other contexts.

CONCLUSION

Clinicians need to be knowledgeable and prepared to understand, and manage complications following laser treatments, as rare as they may be, including KAs.

Multiple Eruptive Keratoacanthomas Secondary to Nivolumab Immunotherapy

Immune checkpoint inhibitors are increasingly being utilized for the treatment of advanced neoplastic disease and have been associated with wide-ranging cutaneous adverse effects. Though exceedingly rare, eruptive keratoacanthomas have been associated with the use of immune checkpoint inhibitors such as pembrolizumab and nivolumab, whose molecular target is the programmed cell death protein 1. Herein, we detail a case of numerous eruptive keratoacanthomas arising in a patient one month after initiation of nivolumab for recurrent metastatic oropharyngeal squamous cell carcinoma. Treatment with multiple rounds of intralesional corticosteroids and a several-month course of oral acitretin resulted in partial improvement. Subsequent treatment with intralesional 5-fluorouracil demonstrated near-complete resolution of the keratoacanthomas without discontinuation of nivolumab. Although eruptive keratoacanthomas secondary to immune checkpoint inhibitors are exceptionally rare, physicians should be aware of this cutaneous adverse effect as their use becomes more widespread.

Identifying SCC Lesions Capable of Spontaneous Regression by Using Immunohistochemistry: A Systematic Review and Meta-Analysis

INTRODUCTION

Keratoacanthoma (KA) and squamous cell carcinoma (SCC) are two cutaneous conditions with morphological resemblance, which can complicate the diagnosis in some cases. Using immunohistochemistry staining of biomarkers could be beneficial in resolving this obstacle.

OBJECTIVES

We investigated a variety of biomarkers assessed in different studies in order to find the most important and helpful biomarkers for differentiation between SCC and lesions capable of spontaneous regression.

METHODS

MEDLINE via PubMed and Google Scholar database were used to identify relevant literature up to 15 June 2022. The aim of our analyses was to determine the capability of biomarkers to distinguish between SCC and lesions capable of spontaneous regression using calculated individual and pooled odds ratios (OR) and 95% confidence intervals (CI) and I2 tests.

RESULTS

Six potential biomarkers were CD10 with pooled OR= 0.006 (95% CI: 0.001-0.057) and I2=0%; COX-2 with pooled OR=0.089 (95% CI: 0.029-0.269) and I2=17.1%; elastic fibers with pooled OR= 6.69 (95% CI: 2.928-15.281) and I2=0%; IMP-3 with pooled OR=0.145 (95% CI: 0.021-1.001) and I2=44.5%; P53 with pooled OR=0.371 (95% CI: 0.188-0.733) and I2=55.9%; AT1R with OR=0.026 (95% CI: 0.006-0.107).

CONCLUSIONS

We suggest the utilization of the following IHC biomarkers for discrimination between lesions with spontaneous regression such as KA and SCC: CD10, COX-2, and elastic fibers.

Pathophysiology, Histopathology, and Differential Diagnostics of Basal Cell Carcinoma and Cutaneous Squamous Cell Carcinoma-An Update from the Pathologist's Point of View

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) are the most frequently occurring non-melanocytic skin cancers. The objective of our study is to present the pathophysiology of BCC and cSCC and its direct relationship with the histopathological diagnostics and the differential diagnostics of these types of cancer, based on the morphological characteristics, immunohistochemical profile, and genetic alterations. The qualitative study was based on emphasizing the morphological characteristics and immunohistochemistry profiles of BCC and cSCC and the differential diagnostics based on the tissue samples from the Clinical Pathology Department of Mures Clinical County Hospital between 2020 and 2022. We analyzed the histopathological appearances and immunohistochemical profiles of BCC and cSCC in comparison with those of Bowen disease, keratoacanthoma, hyperkeratotic squamous papilloma, metatypical carcinoma, pilomatricoma, trichoblastoma, Merkel cell carcinoma, pleomorphic dermal sarcoma (PDS), and melanoma. Our study showed the importance of the correct histopathological diagnosis, which has a direct impact on the appropriate treatment and outcome for each patient. The study highlighted the histopathological and morphological characteristics of NMSCs and the precursor lesions in HE and the immunohistochemical profile for lesions that may make the differential diagnosis difficult to establish.

Distinguishing Keratoacanthoma from Well-Differentiated Cutaneous Squamous Cell Carcinoma Using Single-Cell Spatial Pathology

Keratoacanthoma (KA) is a common keratinocyte neoplasm that is regularly classified as a type of cutaneous squamous cell carcinoma (cSCC) despite demonstrating benign behavior. Differentiating KA from well-differentiated cSCC is difficult in many cases due to the substantial overlap of clinical and histological features. Currently, no reliable discriminating markers have been defined, and consequently, KAs are often treated similarly to cSCC, creating unnecessary surgical morbidity and healthcare costs. In this study, we used RNA sequencing to identify key differences in transcriptomes between KA and cSCC, which suggested divergent keratinocyte populations between each tumor. Imaging mass cytometry was then used to identify single-cell tissue characteristics, including cellular phenotype, frequency, topography, functional status, and interactions between KA and well-differentiated cSCC. We found that cSCC had significantly increased proportions of Ki67+ keratinocytes among tumor keratinocytes, which were dispersed significantly throughout non-basal keratinocyte communities. In cSCC, regulatory T-cells were more prevalent and held greater suppressive capacity. Furthermore, cSCC regulatory T-cells, tumor-associated macrophages, and fibroblasts had significant associations with Ki67+ keratinocytes as opposed to avoidances with KA, indicating a more immunosuppressive environment. Our data suggest that multicellular spatial features can serve as a foundation to enhance the histological discrimination of ambiguous KA and cSCC lesions.

Aberrant p16, p53 and Ki-67 immunohistochemistry staining patterns can distinguish solitary keratoacanthoma from cutaneous squamous cell carcinoma

Keratoacanthoma (KA) is widely considered a benign, usually self-resolving, neoplasm distinct from cutaneous squamous cell carcinoma (cSCC), while some consider KA to be indistinguishable from cSCC. Published studies indicate utility for p16, p53, Ki-67 immunostaining and elastic van Gieson (EVG) in the assessment of KA and cSCC. We compared clinical features and staining patterns for p16, p53, Ki-67 and EVG in fully excised KA, cSCC with KA-like features (cSCC-KAL) and other cSCC (cSCC-OTHER). Significant differences between KA, cSCC-KAL and cSCC-OTHER were found for head and neck location (20%, 86%, 84%), and duration <5 months (95%, 63%, 36%). KA shows both a mosaic pattern for p16 (>25-90% of neoplasm area) and peripheral graded pattern for p53 (up to 50% moderate and strong nuclear staining) in 92% compared with 0% of cSCC-KAL and 0% of cSCC-OTHER. In contrast, a highly aberrant pattern (usually null) for one or both p16 and p53, was present in 0% of KA, 83.8% of cSCC-KAL and 90.9% of cSCC-OTHER. Abnormal distribution of Ki-67 beyond the peripheral 1-3 cells was uncommon in KA (4.2%) and common in cSCC-KAL (67.6%) and cSCC-OTHER (88.4%). Moderate to striking entrapment of elastic and collagen fibres was present in the majority of KA (84%), cSCC-KAL (81%) and cSCC-OTHER (65%). KA are clinically distinct neoplasms typically of short duration occurring preferentially outside the head and neck and generally lacking aberrations of p16, p53 and Ki-67, compared with cSCC that have high rates of aberrant or highly aberrant p16, p53 and Ki-67, but EVG lacked specificity.

Characteristics and Outcomes of Squamous Cell Carcinoma and Other Cutaneous Malignancies in Epidermolysis Bullosa: A Systematic Review

OBJECTIVE

To identify cases and summarize outcomes of cutaneous malignancies in patients with epidermolysis bullosa (EB).

DATA SOURCES

MEDLINE and EMBASE databases were searched on February 8, 2022.

STUDY SELECTION

Original observational or experimental studies with cases of cutaneous malignancy in patients with inherited EB were included.

DATA EXTRACTION

Data were extracted by two reviewers in duplicate.

DATA SYNTHESIS

A total of 87 articles with 367 patients were included in this systematic review. Squamous cell carcinomas were the most common malignancy (94.3%) with a median survival of 60 months. The presence of metastasis was investigated at diagnosis in 77 patients; 18.8% of patients had detectable metastasis. Patients with squamous cell carcinoma with metastasis at diagnosis had significantly shorter median survival (16.8 months) than those without (72 months; P = .027). The remission rate was 47.6%. At the end of follow-up, 15.1% were alive with disease, and 41.6% were deceased. Other malignancies included malignant melanoma and basal cell carcinoma. The most common initial modes of management were excisions (71.9%) and amputations (17.6%). Other modes included chemotherapy (4.6%), radiation (3.9%), and no treatment (2.6%). The overall rate of recurrence or new lesions was 38.8%, with a median time of 16 months to recurrence or new lesions. Immediate recurrence was lowest following amputation (4.3%). There were no statistically significant differences in median survival among initial excision, amputation, and all other modes combined ( P = .30).

CONCLUSIONS

Squamous cell carcinomas in patients with EB have a high likelihood of metastasis and mortality. Surgical excision is the most common intervention. There are no significant differences in survival among different initial management options. There is a need for research that documents and monitors outcomes of the treatment options.

Solitary Keratoacanthoma at the Recipient Site of a Full-Thickness Skin Graft: A Case Report and Review of the Literature

A 57-year-old man presented with a pigmented papule, 0.4 cm in diameter, on the left lower eyelid. Skin biopsy revealed a basal cell carcinoma, which was excised through a wide excision followed by a full-thickness skin graft (FTSG). Two weeks after the surgery, an erythematous nodule developed in the lower margin of the graft recipient site. The nodule size increased rapidly over 2 weeks, becoming dome-shaped with a central hyperkeratotic plug. A diagnosis of keratoacanthoma (KA) was made, and surgical excision was performed. Histological findings revealed a large, well-differentiated squamous tumor with a central keratin-filled crater and buttress. The human papilloma virus (HPV) genotyping results were negative. Risk factors for KA include trauma, old age, exposure to ultraviolet (UV) radiation, immunosuppression, and HPV infection. KA has most often been reported to develop at the donor site. Although the pathogenesis of KA is unclear, trauma is believed to act as a second insult to a preceding oncogenic insult, such as exposure to UV radiation, resulting in a koebnerization. Herein, we report a case of solitary KA at a FTSG recipient site. This report presents information that may provide guidance during dermatologic surgeries.

Interventional treatment of keratoacanthoderma: a case report

This current case report describes a 56-year-old male patient with a skin mass on his lip that had been growing for 1 year. The pathological findings demonstrated that the epidermis was characterized by hyperkeratosis, hyperplasia and hypertrophy and was formed in the shape of a crater. The skin on both ends had developed into a ball-like growth that resembled a volcanic cone. There was invasive growth of heterotype squamous epithelium and a small number of inflammatory cells infiltrating the dermis. Immunohistochemistry demonstrated an increase in P16 (the focus, +) and the hot spot Ki-67 index. The diagnosis was of tumour-like hyperplasia, malignancy and moderate-to-severe dysplasia confirming that it was keratoacanthoma. The patient underwent surgical resection and was discharged from hospital, but the tumour returned. Paclitaxel and cisplatin were administered intraoperatively and bilateral lingual artery perfusion chemoembolization was undertaken six times. This procedure led to an excellent postoperative recovery and discharge from hospital. Tumour therapy was regarded as successful. The patient's medical history included acute lymphoblastic leukaemia L1 and long-term immunosuppressant use. After a 6-month period of follow-up, he died from systemic organ failure as a consequence of having too many ailments.

Computer Image Analysis Reveals C-Myc as a Potential Biomarker for Discriminating between Keratoacanthoma and Cutaneous Squamous Cell Carcinoma

The distinction between Keratoacanthoma (KA) and Cutaneous Squamous Cell Carcinoma (cSCC) is critical yet usually challenging to discriminate clinically and histopathologically. One approach to differentiate KA from cSCC is through assessing the immunohistochemical staining patterns of the three indicators, β-catenin, C-Myc, and CyclinD1, which are critical molecules that play important roles in the Wnt/β-catenin signaling pathway. Ki-67, as a proliferation biomarker for human tumor cells, was also assessed as an additional potential marker for differentiating KA from cSCC. In this report, these four indicators were analyzed in 42 KA and 30 cSCC cases with the use of the computer automated image analysis system. Computer automated image analysis is a time-based and cost-effective method of determining IHC staining in KA and cSCC samples. We found that C-Myc staining was predominantly localized in the nuclei of basal cells within KA patients, whereas cSCC staining was predominantly localized in the nuclei of diffuse cells. This C-Myc staining pattern has a sensitivity of 78.6% and a specificity of 66.7% for identifying KA. Moreover, positive rates of distinct expression patterns of C-Myc and Ki-67 may also serve as a means to clinically distinguish KA from cSCC. Taken together, our results suggest that these markers, in particular C-Myc, may be useful in differentiating KA from cSCC.

Response to "A clinical and biological review of keratoacanthoma": reply from authors

We appreciate the interest of the authors in our review of keratoacanthoma (KA).¹ They raise several points that were discussed in our manuscript. First, they suggest that the histopathological differentiation from KA and well-differentiated squamous cell carcinoma (SCC) is not as problematic as reviewed; however, they qualify that an "adequate specimen is required" and "partial biopsies are not reliable." This is a key point we discussed, as a portion of biopsies may be too small to identify important architectural features or may be unrepresentative of the tumor, which limits the ability of the pathologist to distinguish between KA and SCC^2-4 , and typically leads to an overcall of SCC to avoid a missed malignancy. Indeed, most experienced dermatopathologists can accurately discriminate between KA and SCC when an ample biopsy representative of the tumor is obtained. Second, they question the practicality of using the stereotypical triphasic evolution pattern of KA to aid in diagnosis and state that "patient history is likely to be unreliable."

What Is a Solitary Keratoacanthoma? A Benign Follicular Neoplasm, Frequently Associated with Squamous Cell Carcinoma

We present histopathological criteria for diagnosing keratoacanthoma (KA). In KA, four histological stages are recognized, which are the early/proliferative stage, well-developed stage, regressing stage and regressed stage. In diagnosing KA, we emphasize that KA consists of the proliferation of enlarged pale pink cells with ground glass-like cytoplasm without nuclear atypia, other than crateriform architecture. KA sometimes exhibits malignant transformation within the lesions. We describe the characteristics of benign and malignant epithelial crateriform tumors that should be differentiated from KA. We also present the data of histopathological diagnosis of lesions clinically diagnosed as KA, its natural course and related lesions after partial biopsy, and incidence of crateriform epithelial neoplasms. Based on these data, we recommend complete excision of the lesion when KA is clinically suspected, especially when the lesion is located on a sun-exposed area of an elderly patient. If complete excision is impossible, partial excision of a sufficient specimen with intact architecture is required. In such a case, however, careful investigation after biopsy will be needed, even if the histopathological diagnosis is KA, because there is some possibility that a conventional SCC lesion remains in the residual tissue.