Basosquamous Carcinoma: Controversy, Advances, and Future Directions

Basosquamous carcinoma: a survey study on current management in the UK

Basosquamous carcinoma (BSC) is a rare, aggressive nonmelanoma skin cancer with overlapping features of basal cell carcinoma and squamous cell carcinoma, often requiring histopathological analysis for accurate diagnosis. Our study surveyed UK dermatologists on their management practices for BSC, revealing significant variability in disease categorization, treatment approaches and follow-up protocols, with a noted lack of standardized guidelines. The findings of this study underscore the need for prospective studies and the development of treatment guidelines to improve the management of BSC.

Basosquamous Carcinoma: A Rare Entity With an Atypical Presentation

Basosquamous carcinoma (BSC) is a rare entity of basal cell carcinomas. It is described as being nosologically at the border between a squamous cell carcinoma and a basal cell carcinoma, thus sharing characteristics of both entities. The frequency of this pathology remains low with a few cases reported in the literature. We report the observation of a basosquamous carcinoma with a particular topography on the pulp of the left fifth finger. A histological examination confirmed the diagnosis. Locoregional and general extension studies were negative. Management consisted of surgical resection.

Biomarkers in Cutaneous Keratinocyte Carcinomas

Skin cancer is the most common cancer type in the USA, with over five million annually treated cases and one in five Americans predicted to develop the disease by the age of 70. Skin cancer can be classified as melanoma or non-melanoma (NMSC), the latter including basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (SCC). Development of BCC and SCC is impacted by environmental, behavioral, and genetic risk factors and the incidence is on the rise, with the associated number of deaths surpassing those caused by melanoma, according to recent reports. Substantial morbidity is related to both BCC and SCC, including disfigurement, loss of function, and chronic pain, driving high treatment costs, and representing a heavy financial burden to patients and healthcare systems worldwide. Clinical presentations of BCC and SCC can be diverse, sometimes carrying considerable phenotypic similarities to benign lesions, and underscoring the need for the development of disease-specific biomarkers. Skin biomarker profiling plays an important role in deeper disease understanding, as well as in guiding clinical diagnosis and patient management, prompting the use of both invasive and non-invasive tools to evaluate specific biomarkers. In this work, we review the known and emerging biomarkers of BCC and SCC, with a focus on molecular and histologic biomarkers relevant for aspects of patient management, including prevention/risk assessments, tumor diagnosis, and therapy selection.

Recent Research Trends against Skin Carcinoma - An Overview

Skin cancer is a prevalent and sometimes lethal cancer that affects a wide range of people. UV radiation exposure is the main cause of skin cancer. Immunosuppression, environmental factors, and genetic predisposition are other contributing variables. Fair-skinned people and those with a history of sunburns or severe sun exposure are more likely to experience this condition. Melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) are the three main forms. Melanoma poses a bigger hazard because of its tendency for metastasis, while SCC and BCC have limited metastatic potential. Genetic mutations and changes to signalling pathways such as p53 and MAPK are involved in pathogenesis. Early diagnosis is essential, and molecular testing, biopsy, dermoscopy, and visual inspection can all help. In addition to natural medicines like curcumin and green tea polyphenols, treatment options include immunotherapy, targeted therapy, radiation, surgery, and chemotherapy. Reducing the incidence of skin cancer requires preventive actions, including sun protection and early detection programs. An overview of skin cancers, including their forms, pathophysiology, diagnosis, and treatment, highlighting herbal therapy, is given in this review.

Basosquamous Carcinoma Arising from the Vulva: A Case Report

Introduction

Basosquamous carcinoma (BSC) of the vulva is an uncommon tumor that primarily consists of basal cell carcinoma with squamous differentiation. Also known as metatypical basal cell carcinoma, BSC is typically classified as a skin cancer and represents only 2% of non-melanoma skin malignancies. This type of carcinoma has a poorer prognosis than basal cell carcinoma due to its increased local aggressiveness and metastatic potential.

Case Presentation

We present the case of a 59-year-old woman with a 3-year history of a slow-growing and painful vulvar lesion. Clinical examination revealed a 35-mm nodular, ulcerating, and non-pigmented lesion located on the labia majora. A biopsy confirmed the diagnosis of BSC, and staging assessments indicated no evidence of metastasis. The patient underwent partial radical vulvectomy and sentinel lymph node biopsy, with histological analysis revealing distinct features characteristic of BSC, including basaloid cell islands and areas of significant squamous differentiation. The excision margins were tumor-free, and all six lymph nodes examined were negative for metastases. Regular surveillance for 6 months was conducted without signs of recurrence.

Conclusion

After reviewing the literature, this case represents the sixth documented instance of vulvar BSC. Compared to basal cell carcinoma, BSC has a poorer prognosis, with a higher potential for recurrences and metastases. While basal cell carcinoma is much more prevalent among vulvar and skin malignancies, recognizing the squamous differentiation component is crucial for ensuring wider margins during surgical excision.

Basosquamous Carcinoma: Comprehensive Clinical and Histopathological Aspects, Novel Imaging Tools, and Therapeutic Approaches

Basosquamous carcinoma (BSC), an uncommon and aggressive nonmelanoma skin cancer exhibiting characteristics ranging from basal cell carcinoma (BCC) to squamous cell carcinoma (SCC), is a subject of controversy in terms of its classification, pathogenesis, histologic morphology, biologic behavior, prognosis, and management. This narrative review is based on an electronic search of English-language articles in PubMed that included the terms "basosquamous carcinoma" and/or "metatypical carcinoma of the skin" in their titles. The review aims to succinctly present and assess current data on the epidemiology, clinical presentation, dermoscopic, LC-OCT, and histopathologic characteristics, as well as the genetics and management of BSC, providing insight into this intriguing entity. As a conclusion, dermoscopy, deep incisional biopsies, and immunohistologic techniques should be applied in clinically suspicious lesions to achieve an early diagnosis and better prognosis of this tumor. Surgical treatments, including wide excision and Mohs' micrographic surgery, remain the treatment of choice. Finally, Hedgehog pathway inhibitors and checkpoint inhibitors, must be thoroughly investigated with large controlled trials, since they may offer an alternative solution to irresectable or difficult-to-treat locally advanced cases of basosquamous carcinoma.

c-FOS Expression in Metastatic Basal Cell Carcinoma with Spontaneous Basosquamous Transition

Abstract is missing (Short communication)

Adequacy of surgical margins, re-excision, and evaluation of factors associated with recurrence: a retrospective study of 769 basal cell carcinomas

BACKGROUND

Achieving adequate surgical margins and preventing recurrence are important in the treatment of basal cell carcinoma (BCC).

OBJECTIVES

The objectives of this study were to evaluate the adequacy of surgical margins and the re-excision rates in patients with primary BCC who underwent standard surgical treatment using our proposed algorithm and to define the risk factors in patients with recurrent BCC.

METHODS

The medical records of patients who were histopathologically diagnosed with BCC were reviewed. An algorithm created based on previous literature was used to determine the distribution of optimal surgical margins adequacy and re-excision rates.

RESULTS

Statistically significant differences were observed between the cases with and without recurrence in age at diagnosis (p=0.004), tumor size (p=0.023), tumor location in the H zone of the face (p=0.005), and aggressive histopathological subtype (p=0.000). When the tumors were evaluated for adequacy of deep and lateral surgical margins and re-excision rates, higher rates of adequate excision (457 cases, 68.0%) and re-excision (43 cases, 33.9%) were noted for tumors in the H or M zone.

STUDY LIMITATIONS

Inadequate follow-up of newly diagnosed patients in terms of recurrence and metastasis and the retrospective application of our proposed algorithm are the limitations of the present study.

CONCLUSIONS

Our results showed that if BCC was detected at an early age and at an early stage, recurrence was lower. The H and M zones were the regions with the highest rates of optimal surgical outcomes.

Basosquamous Cell Carcinoma of the Nipple-Areola Complex-Report of a Case

Basosquamous cell carcinoma (BSCC) is a rare malignancy usually arising on sun-exposed areas of the skin. BSCC is described as a rare variant of Basal cell carcinoma (BCC) which shows clinical and microscopic features of both BCC and of Squamous cell carcinoma (SCC). We report the case of a 70-year-old male with a cutaneous lesion of the nipple-areola complex (NAC); to the best of our knowledge, this is the first ever reported patient with BSCC in this area. The lesion had a fast growth, but, due to the COVID19 crisis, the patient only came to our observation one year after onset of this condition. Physical examination showed a bleeding red ulcerated lesion that involved the NAC, measuring 27 mm × 20 mm. Biopsy showed a BSCC. Pre-operative breast ultrasound scan, mammogram and MRI were all performed before surgery, which consisted of simple mastectomy and sentinel lymph-node biopsy. The patient was discharged home on the 4th post-operative day, and at 18-month follow-up there are no signs or clinical evidence of local recurrence or metastases. Diagnosis of BSCC of the nipple-areola complex requires high index of suspicion and a thorough differential diagnosis, management, and suitable radical treatment due to well described high rates of recurrence and of metastases. Differential diagnosis with similar lesions (e.g., Paget's disease, Bowen's disease, BCC, and SCC) should also be taken into account.

LY6D marks pre-existing resistant basosquamous tumor subpopulations

Improved response to canonical therapies requires a mechanistic understanding of dynamic tumor heterogeneity by identifying discrete cellular populations with enhanced cellular plasticity. We have previously demonstrated distinct resistance mechanisms in skin basal cell carcinomas, but a comprehensive understanding of the cellular states and markers associated with these populations remains poorly understood. Here we identify a pre-existing resistant cellular population in naive basal cell carcinoma tumors marked by the surface marker LY6D. LY6D+ tumor cells are spatially localized and possess basal cell carcinoma and squamous cell carcinoma-like features. Using computational tools, organoids, and spatial tools, we show that LY6D+ basosquamous cells represent a persister population lying on a central node along the skin lineage-associated spectrum of epithelial states with local environmental and applied therapies determining the kinetics of accumulation. Surprisingly, LY6D+ basosquamous populations exist in many epithelial tumors, such as pancreatic adenocarcinomas, which have poor outcomes. Overall, our results identify the resistant LY6D+ basosquamous population as an important clinical target and suggest strategies for future therapeutic approaches to target them.

Basosquamous Carcinoma: A Commentary

Simple Summary

Basosquamous carcinoma is a rare, aggressive non-melanoma skin cancer with features that lie between those of basal cell carcinoma and squamous cell carcinoma. A lot of controversy has been raised around the classification, pathogenesis, histologic morphology, biologic behavior, prognosis and management of this tumor. This is a narrative review based on articles published on PubMed in English language which had in their title the terms “basosquamous carcinoma” and/or “metatypical carcinoma of the skin”. The aim of this review was to summarize and evaluate the latest data of the English literature regarding epidemiology, clinical presentation, dermoscopic and histopathologic characteristics, as well as the genetics and management of BSC to better characterize basosquamous skin lesions.

Abstract

Basosquamous carcinoma is a rare, aggressive non-melanoma skin cancer with features that lie between those of basal cell carcinoma and squamous cell carcinoma. A lot of controversy has been raised around the classification, pathogenesis, histologic morphology, biologic behavior, prognosis and management of this tumor. This is a narrative review based on an electronic search of articles published in PubMed in English language which had in their title the terms “basosquamous carcinoma” and/or “metatypical carcinoma of the skin”. The aim of this review was to summarize and evaluate current data regarding epidemiology, clinical presentation, dermoscopic and histopathologic characteristics, as well as the genetics and management of BSC, in order to shed some more light onto this intriguing entity. As a conclusion, dermoscopy, deep incisional biopsies and immunohistologic techniques (Ber-EP4) should be applied in clinically suspicious lesions in order to achieve an early diagnosis and better prognosis of this tumor. Surgical treatments, including wide excision and Mohs’ micrographic surgery, remain the treatment of choice. Finally, vismodegib, a Hedgehog pathway inhibitor, must be thoroughly investigated, with large controlled trials, since it may offer an alternative solution to irresectable or difficult-to-treat, locally advanced cases of basosquamous carcinoma.

c-FOS drives reversible basal to squamous cell carcinoma transition

While squamous transdifferentiation within subpopulations of adenocarcinomas represents an important drug resistance problem, its underlying mechanism remains poorly understood. Here, using surface markers of resistant basal cell carcinomas (BCCs) and patient single-cell and bulk transcriptomic data, we uncover the dynamic roadmap of basal to squamous cell carcinoma transition (BST). Experimentally induced BST identifies activator protein 1 (AP-1) family members in regulating tumor plasticity, and we show that c-FOS plays a central role in BST by regulating the accessibility of distinct AP-1 regulatory elements. Remarkably, despite prominent changes in cell morphology and BST marker expression, we show using inducible model systems that c-FOS-mediated BST demonstrates reversibility. Blocking EGFR pathway activation after c-FOS induction partially reverts BST in vitro and prevents BST features in both mouse models and human tumors. Thus, by identifying the molecular basis of BST, our work reveals a therapeutic opportunity targeting plasticity as a mechanism of tumor resistance.

Basal cell carcinoma-not always the 'good guy': Case report of a life-threatening basosquamous carcinoma and review of the literature

Cutaneous basosquamous carcinoma is a variant of basal cell carcinoma that is characterized by histopathological features of both basal and squamous cell carcinoma. Due to its local invasiveness, high frequency of recurrence, and its metastatic potential, it is considered to be one of the most aggressive subtypes of basal cell carcinoma. We present the case of an 81-year-old male who was admitted to the hospital with incessant hemorrhage arising from a cutaneous tumor that later proved to be a basosquamous carcinoma. Due to the COVID-19 pandemic at the time, the patient did not seek medical attention as soon as the bleeding was observed, although he did present when the symptom increased in intensity and became incessant. To our knowledge, this is the first case report of a cutaneous basosquamous carcinoma that presents with a massive life-threatening hemorrhage tumor, thus endangering the patient's life. The clinical and histopathological features, the behavior and the treatment of cutaneous basosquamous carcinoma are further reviewed in this article.

Combination of squamous cell carcinoma and basal cell carcinoma arising from a giant verruca vulgaris involving the eyelid

Purpose

Verruca Vulgaris is a common benign cutaneous lesion which only reported occasionally to have malignant potential. Our purpose is to report a rare case of verruca vulgaris involving the eyelid and subsequently transformed into the combination of squamous cell carcinoma and basal cell carcinoma.

Observations

We reported a case of a 97-year-old female with a chronic biopsy proven verruca vulgaris involving the left lateral canthus. She presented with pain and swelling 5 years after the biopsy. Physical examination showed a painful warty crushed growth mass surrounded by erythematous skin changes, sized 40 × 40mm. Excisional biopsy showed squamous cell carcinoma and a microscopic focus of basal cell carcinoma.

Conclusions and importance

Our case demonstrates the oncogenic potential of verruca vulgaris into the combination of squamous cell carcinoma and basal cell carcinoma within one lesion. Size, chronicity and UV radiation may increase the risk of malignancy. Early surgical excision should be considered in eyelid involving chronic verruca vulgaris.

Clinical and epidemiological analysis of basosquamous carcinoma: results of the multicenter study

Basosquamous carcinoma (BSC) is a rare non-melanoma skin cancer that shares the characteristic features of both basal and squamous cell carcinomas (BCC, SCC). Our research enables better characterization of BSC in comparison to high-risk subtypes of BCC and SCC. Paper includes a retrospective analysis of BSC cases regarding sex, age, number of tumors and anatomical distribution in comparison to BCC and SCC evaluating the differences and defining the implications. Histologically confirmed carcinomas recorded between 1999 and 2019 were studied. 181 diagnosed BSC cases were identified, making this study the largest cohorts of BSC patients reported worldwide. Most cases were reported on head and neck. Analysis of facial anatomic distribution shows that most commonly affected sites were the nose (43%) and the cheek (25%). The age at excision of metatypical BCC was higher than those of low-risk BCC (P < 0.05), however similar to high-risk BCC (P = 0.20). We revisited that the concept of BSC is the most similar to high-risk subtypes of BCC. Patients with diagnosed BSC have higher risk of second nonmelanoma skin cancer. Therefore, the frequency of follow-up examination should be adjusted to the individual risk of another skin cancer.

Upstaging of basal cell and squamous cell carcinomas during definitive surgery: a review of predictive preoperative clinical and histologic features

The incidence of nonmelanoma skin cancer (NMSC) in the United States is increasing with approximately 3.6 million cases diagnosed per year. The staging and treatment of NMSC is guided by histologic subtype based on skin biopsy, along with other tumor-specific factors. However, a biopsy only represents a portion of the tumor, so there is a risk of upstaging at the time of definitive surgery. We conducted a review of the literature and found that a significant proportion of NMSC were upstaged during surgery. The rate of upstaging of basal cell carcinoma (BCC) was 7-31% and that of squamous cell carcinoma in situ (SCCIS) to squamous cell carcinoma (SCC) was 3-39%. Biopsy sampling error and variability in interpreting and reporting by dermatopathologists contribute to these discrepancies. It is pertinent to consider more comprehensive treatment modalities for tumors at high risk for upstaging. Diligence to identify tumors at higher risk for upstaging will allow clinicians to optimize management.

Collision tumors: A review of their types, pathogenesis, and diagnostic challenges

A collision tumor is a neoplastic lesion comprised of two or more distinct cell populations that maintain distinct borders. Collision tumors, which are rare but well documented, can be composed of two benign tumors, a benign and malignant tumor, and two malignant tumors. Although case reports and reviews on specific types of collision tumors exist, a cohesive source discussing these tumors is lacking. We critically reviewed the literature by analyzing case reports and retrospective studies in order to evaluate the following regarding collision tumors: definitions, types, pathogenesis, diagnosis, and management. Reports of these tumors are infrequent but not insignificant, and accurate classification and diagnosis will lead to better patient outcomes.

Non-Melanoma Skin Cancers: Biological and Clinical Features

Non-melanoma skin cancers (NMSCs) include basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and Merkel cell carcinoma (MCC). These neoplasms are highly diverse in their clinical presentation, as well as in their biological evolution. While the deregulation of the Hedgehog pathway is commonly observed in BCC, SCC and MCC are characterized by a strikingly elevated mutational and neoantigen burden. As result of our improved understanding of the biology of non-melanoma skin cancers, innovative treatment options including inhibitors of the Hedgehog pathway and immunotherapeutic agents have been recently investigated against these malignancies, leading to their approval by regulatory authorities. Herein, we review the most relevant biological and clinical features of NMSC, focusing on innovative treatment approaches.

Reappraising basosquamous carcinoma: a summary of histologic features, diagnosis, and treatment

Basosquamous carcinoma (BSC) is a malignant and aggressive neoplasm with unclear molecular etiology. It is often misdiagnosed as basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) on biopsy as there are unclear histologic criteria for this neoplasm. It has been interchangeably referred to as metatypical BCC and collision tumor, although these entities are different. On histology, BSC consists of basal cells with areas with nests of squamous cells and an intermediate transition zone. The nature of this transition zone is not clearly defined in literature; however, Ber-EP4 staining is diagnostic for BSC. A gradation of Ber-EP4 staining from strongly positive in basaloid areas to weakly positive in an intermediate zone is demonstrated (no staining of squamous areas). Treatment with an array of modalities including wide local excision, Mohs surgery, radiotherapy, and palliative chemotherapy has been performed. We recommend further molecular studies in understanding the genetic mechanisms leading to BSC. For the purpose of good clinical practice, multiple biopsies and immunohistochemical studies should be performed to avoid sampling error that can lead to a misdiagnosis of BSC.

Giant basal cell carcinoma associated with vitiligo

We report a woman with two giant Basal cell carcinomas (BCCs) on the back, the largest with 12 cm in diameter, inside a vitiligo plaque. They were metatypical subtype BCC associated with a nodular subtype area. Thinking of BCC in vitiligo lesion is extremely important. Giant BCC and vitiligo are rare association.

Detection of Felis catus papillomavirus type 2 within multicentric basosquamous carcinoma in a domestic cat

A 12-year-old neutered male domestic shorthair cat was presented with a 3-year history of multiple nonpruritic, ulcerated, plaque-like skin lesions but no other clinical signs. A systemic examination revealed mild lymphadenopathy. Histopathologic analysis of the skin lesions revealed multicentric basosquamous carcinoma (BSC). Immunohistochemical analysis, PCR, and sequencing detected Felis catus papillomavirus type 2 (FcaPV-2) within the tumors. As BSC is rare in cats, clinical behavior has not been established. To our knowledge, this is the first case report to demonstrate detection of FcaPV-2 within a BSC in a domestic cat.

Ocular preservation with neoadjuvant vismodegib in patients with locally advanced periocular basal cell carcinoma

Background/Aims

Locally advanced (T4 per American Joint Committee on Cancer (AJCC) 8th edition) periocular basal cell carcinoma (BCC) can lead to loss of the eye. We report the neoadjuvant use of vismodegib followed by surgery in patients with such lesions with eye preservation as primary goal.

Methods

This retrospective interventional study includes all patients with a T4 periocular BCC (per 8th edition AJCC for eyelid carcinoma) treated by the senior author between 2013 and 2017 with neoadjuvant vismodegib prior to definitive surgery.

Results

Eight patients had a T4 tumour. Six patients presented with recurrent disease. Indications for neoadjuvant treatment were an unresectable tumour in one patient, an attempt to avoid an orbital exenteration in six patients and an attempt to avoid disfiguring facial surgery in one patient. Patients were treated for a median of 14 months (range: 4–36 months). All patients underwent an eye-sparing surgery following neoadjuvant vismodegib and all final surgical margins were negative for tumour. Five patients had a complete response to vismodegib with no microscopic residual BCC found during surgery; three patients had a significant partial response with residual tumour found on pathology. At last follow-up, a mean of 18 (range: 6–43) months after surgery, all patients were off-vismodegib and alive without evidence of disease.

Conclusions

Neoadjuvant vismodegib for locally advanced (T4) periocular BCC enabled an eye-sparing surgery in all patients in our cohort. Prolonged treatment was well tolerated by most patients. Over half of patients achieved a complete response with no residual microscopic disease. Careful long-term follow-up is needed to confirm long-term disease-free survival.

Basosquamous Carcinoma: A Single Centre Clinicopathological Evaluation and Proposal of an Evidence-Based Protocol

Basosquamous carcinoma (BSC) is an uncommon skin malignancy with significant invasive and metastatic potential. There are currently no clear management guidelines. This study evaluates the management and outcomes of patients diagnosed with BSC over a 7-year period. We present an evidence-based unit protocol for the management of BSC. All patients treated for BSC between 2009 and 2015 were reviewed. Data collected included patient demographics, tumour-specific information, management strategy, presence of recurrence or metastasis, and details of follow-up. 74 patients were identified, making this one of the largest cohorts of BSC patients reported. Mean age at diagnosis was 75.4 years, with a male:female ratio of 1.6:1. The most common tumour site was the head and neck (n=43, 58.1%). All tumours were graded at pT1 (n=51) or pT2 (n=23). Inadequate excision occurred in 17 patients (23%). Mean excision margins were >4mm peripherally and deep. Inadequately excised BSCs were further treated with wide local excision (n=6) or radiotherapy (n=5), or both (n=1). There were no cases of local recurrence or metastatic disease. This study demonstrates a cohort of patients with BSCs that appear less aggressive than previously reported. Current management with surgical excision appears to produce adequate results. However, an evidence-based guideline is still lacking.