Cutaneous squamous cell carcinoma: a comprehensive clinicopathologic classification. Part one

Grading differentiation in cutaneous squamous cell carcinoma: a review of the literature

Poor differentiation is strongly associated with poor outcomes in cutaneous squamous cell carcinoma (CSCC). In addition, the National Comprehensive Cancer Network (NCCN) guidelines designate poorly differentiated tumors as "very high risk". Despite its clear prognostic implications, there is no standardized grading system for CSCC differentiation in common use today. CSCC differentiation is graded inconsistently by both dermatopathologists and Mohs surgeons, and reliability studies have demonstrated suboptimal inter- and intra-rater reliability in both of these groups. The absence of a standardized and reliable grading system has impeded the use of differentiation in CSCC staging, despite its apparent correlation with disease outcomes. We performed a comprehensive review of the literature summarizing historical CSCC differentiation grading systems, as well as grading systems in non-cutaneous head and neck SCC as a point of reference. Relevant articles were identified by searching Embase and PubMed, as well as by reviewing reference lists for additional articles and histology textbook excerpts. CSCC grading systems that were identified and summarized include the historical Broders system, the World Health Organization system, the College of American Pathologists' system, and a system described by a 2023 Delphi consensus panel of dermatopathologists.

miR-22 promotes stem cell traits via activating Wnt/β-catenin signaling in cutaneous squamous cell carcinoma

Emerging evidence suggests that the cancer stem cells (CSCs) are key culprits of cancer metastasis and drug resistance. Understanding mechanisms regulating the critical oncogenic pathways and CSCs function could reveal new diagnostic and therapeutic strategies. We now report that miR-22, a miRNA critical for hair follicle stem/progenitor cell differentiation, promotes tumor initiation, progression, and metastasis by maintaining Wnt/β-catenin signaling and CSCs function. Mechanistically, we find that miR-22 facilitates β-catenin stabilization through directly repressing citrullinase PAD2. Moreover, miR-22 also relieves DKK1-mediated repression of Wnt/β-catenin signaling by targeting a FosB-DDK1 transcriptional axis. miR-22 knockout mice showed attenuated Wnt/β-catenin activity and Lgr5+ CSCs penetrance, resulting in reduced occurrence, progression, and metastasis of chemically induced cutaneous squamous cell carcinoma (cSCC). Clinically, miR-22 is abundantly expressed in human cSCC. Its expression is even further elevated in the CSCs proportion, which negatively correlates with PAD2 and FosB expression. Inhibition of miR-22 markedly suppressed cSCC progression and increased chemotherapy sensitivity in vitro and in xenograft mice. Together, our results revealed a novel miR-22-WNT-CSCs regulatory mechanism in cSCC and highlight the important clinical application prospects of miR-22, a common target molecule for Wnt/β-catenin signaling and CSCs, for patient stratification and therapeutic intervention.

When is a surgical multidisciplinary approach required in the management of head and neck non-melanoma skin cancer and in advanced head and neck pathologies involving skin?

Non-melanoma Skin cancer, including cutaneous squamous cell carcinoma and basal cell carcinoma, is the most common form of malignancy in the Caucasian population, and the skin of the head and neck is the site most involved. They should not be underestimated; in particular, high-risk lesions and advanced skin cancers require accurate diagnostic work up, aggressive surgical treatment and should be managed by the head and neck surgeon, the dermatologist and the plastic surgeon. Cutaneous head-neck malignancies are often overlooked or not routinely treated with a multidisciplinary surgical approach. Similarly, for primary head and neck cancers with involvement of surrounding skin, the involvement of the dermatologist and the plastic surgeon could better define an adequate diagnosis and treatment planning. The management of these patients presents both therapeutic and ethical problems, because the poor prognosis is burdened by facial disfigurement, open malodorous wounds and intractable pain. Therefore, in patients with advanced disease that is not candidate to radical surgery, palliative surgery with flap reconstruction could take place and could be proposed to improve quality of life.

Clinicopathological Correlations in Cutaneous Squamous Cell Carcinomas

Squamous cell carcinomas (SCC) represent 20% of all nonmelanoma skin cancers, most tumors responding favorably to the conventional therapy. Incisional or excisional biopsy is essential for diagnosis and prognosis evaluation. The study included 103 cases of SCC, following the assessment of some clinical and histopathological aggressivity factors, which were digitally stored and statistically analyzed using comparison tests. The tumor grade was significantly associated with the histological variant, the maximum tumor size, the perineural and lymphovascular invasion, the depth of the invasion and the status of resection limits. The pT category was significantly associated with the location and maximum tumor size, perineural invasion, depth of invasion and status of resection limits. It was observed a significant association of tumor grade and pT category. The evaluation of the clinical and histological characteristics of SCC is an important step in obtaining relevant prognostic information and applying appropriate therapy.

Successful use of immunotherapy to treat advanced cutaneous squamous cell carcinoma in recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a multisystem inherited disorder associated with fragile skin, blister formation and poor wound healing. Patients with RDEB are at significantly increased risk of recurrent and aggressive cutaneous squamous cell carcinoma (cSCC) and because of their disease complexity, conventional therapies may not be possible. Recent advances in cancer immunotherapy have led to the successful use of immune checkpoint inhibitors (ICIs) in melanoma and other malignancies. However, the effects of ICIs in patients with cSCC and RDEB are currently unknown. A 30-year-old woman with RDEB and multiple unresectable cSCCs was found to have high tumour mutational burden and PD-L1 (programmed cell death-ligand 1) expression. She was started on an ICI, which yielded disease control and was well tolerated. Furthermore, her RDEB wounds improved. This case demonstrates successful use of immunotherapy for advanced cSCC in RDEB, a disease that is often challenging to treat with local therapies.

Cutaneous Squamous Cell Carcinoma: From Pathophysiology to Novel Therapeutic Approaches

Cutaneous squamous cell carcinoma (cSCC), a non-melanoma skin cancer, is a keratinocyte carcinoma representing one of the most common cancers with an increasing incidence. cSCC could be in situ (e.g., Bowen’s disease) or an invasive form. A significant cSCC risk factor is advanced age, together with cumulative sun exposure, fair skin, prolonged immunosuppression, and previous skin cancer diagnoses. Although most cSCCs can be treated by surgery, a fraction of them recur and metastasize, leading to death. cSCC could arise de novo or be the result of a progression of the actinic keratosis, an in situ carcinoma. The multistage process of cSCC development and progression is characterized by mutations in the genes involved in epidermal homeostasis and by several alterations, such as epigenetic modifications, viral infections, or microenvironmental changes. Thus, cSCC development is a gradual process with several histological- and pathological-defined stages. Dermoscopy and reflectance confocal microscopy enhanced the diagnostic accuracy of cSCC. Surgical excision is the first-line treatment for invasive cSCC. Moreover, radiotherapy may be considered as a primary treatment in patients not candidates for surgery. Extensive studies of cSCC pathogenic mechanisms identified several pharmaceutical targets and allowed the development of new systemic therapies, including immunotherapy with immune checkpoint inhibitors, such as Cemiplimab, and epidermal growth factor receptor inhibitors for metastatic and locally advanced cSCC. Furthermore, the implementation of prevention measures has been useful in patient management.

Primary Cutaneous Myxoid Spindle Cell Squamous Cell Carcinoma of the Scalp: A Case Report

Cutaneous squamous cell carcinomas are the second most frequent type of non-melanoma skin cancer. A 78-year-old man with a slow-growing but large nodular lesion on his scalp presented to the hospital. The nodular lesion was excised. Histologically, the lesion was diagnosed as a primary cutaneous myxoid spindle cell squamous cell carcinoma, which is the subject of this case report. Extracellular mucin production is an even less common finding in SCC. We also aim to discuss the histological and immunohistochemical findings for distinguishing MSC SCC from other primary cutaneous and metastatic spindle cell neoplasms with myxoid stroma.

Cytoplasmic Increase in Hsp70 Protein: A Potential New Biomarker of Early Infiltration of Cutaneous Squamous Cell Carcinoma Arising from Actinic Keratosis

BACKGROUND

Cutaneous squamous skin cell carcinoma (SCC) is the second most frequent type of non-melanoma skin cancer and is the second leading cause of death by skin cancer in Caucasian populations. However, at present it is difficult to predict patients with poor SCC prognosis.

OBJECTIVE

To identify proteins with expression levels that could predict SCC infiltration in SCC arising from actinic keratosis (SCC-AK).

METHODS

A total of 20 biopsies from 20 different patients were studied; 10 were SCC-AK samples and 10 were taken from normal skin. Early infiltrated SCC-AK samples were selected based on histological examination, and to determine the expression of proteins, fresh skin samples were processed by two-dimensional electrophoresis.

RESULTS

The expression levels of three proteins, namely alpha hemoglobin and heat shock proteins 27 and 70 (Hsp27 and Hsp70, respectively) were significantly increased in SCC-AK samples with respect to normal control skin. However, only the expression level of Hsp70 protein positively correlated with the level of SCC-AK dermis infiltration. Immunohistological examination suggested that increased expression of Hsp70 proteins seemed to mainly occur in the cytoplasm of keratinocytes. The increased cytoplasmic Hsp70 expression in SCC-AK was confirmed by Western blot experiments.

CONCLUSION

Cytoplasmic expression of Hsp70 could be a potential biomarker of early infiltration of SCC arising from AK.

Unusual Presentation of Cutaneous Spindle Cell Squamous Cell Carcinoma: A Case Report

Cutaneous spindle cell squamous cell carcinoma (SpSCC) is a rare and often aggressive subtype of squamous cell carcinoma (SCC), which usually appears in sun-exposed areas, in areas that have received prior ionizing radiation, or in immunosuppressed individuals. SpSCCs are histologically characterized by keratinocytes infiltrating the dermis as single cells with elongated nuclei rather than as cohesive nests or islands and, in contrast to conventional SCC, are lacking features of keratinization. Immunohistochemical studies are useful to distinguish SpSCC from other spindle cell neoplasms, such as spindle cell/desmoplastic melanoma, cutaneous leiomyosarcoma, and atypical fibroxanthoma. We present a rare case of a patient with SpSCC in the gluteal region with regional lymph node metastasis. The patient was treated with wide excision of the tumor, inguinal lymph node dissection, and adjuvant radiotherapy. Cutaneous SpSCC is clinically similar to conventional SCC but can demonstrate more aggressive behavior. This case is rare since it was localized in the gluteal region of an otherwise healthy man.

Acantholytic Squamous Cell Carcinoma and Salivary Duct Carcinoma Ex-pleomorphic Adenoma of the Submandibular Gland: A Report of Two Extremely Rare Cases with an Immunohistochemical Analysis

Carcinoma ex pleomorphic adenoma (CXPA) is a malignant tumor of the salivary gland that arises from pleomorphic adenoma (PA). Squamous cell carcinoma (SCC) is extremely rare in the salivary glands. We report two cases of acantholytic SCC (ASCC) ex PA. Case 1 involved a 72-year-old female, and case 2 involved a 67-year-old male. Histologically, both cases involved PA, and salivary duct carcinoma (SDC) components, which were positive for androgen receptor (AR) and gross cystic disease fluid protein (GCDFP)-15 but negative for HER2, were seen in the intracapsular regions. The invasive components consisted of ASCC, which were positive for cytokeratin 5/6 and p63 but negative for AR and GCDFP-15. The SDC and ASCC components were positive for the epidermal growth factor receptor. In both cases, the cytoplasmic localization or decreased expression of E-cadherin was observed in the ASCC. In the early phase, CXPA might emerge as SDC, and it might change into SCC as it invades beyond the capsule due to changes in microenvironment. Also, the aberrant expression of E-cadherin is related to acantholysis in SCC.

Lymphoepithelioma-like carcinoma of the skin

Primary cutaneous lymphoepithelioma-like carcinoma is a rare disease with low metastatic potential. Its morphologic and pathological features are similar to those of nasopharyngeal lymphoepithelial carcinoma. We report the case of a 60-year-old man with an infrapalpebral pearly papule, measuring 0.6 cm in diameter. The lesion was excised with a clinical hypothesis of basal cell carcinoma or squamous cell carcinoma. Histopathological analysis revealed a malignant neoplasm with syncytial arrangement of cells with vesicular nuclei, associated with dense lymphocytic infiltrate. Immunohistochemistry revealed cytokeratin-positive cells (AE1/AE3) and p63 protein, indicating epithelial histogenesis and squamous differentiation. A negative Epstein-Barr virus test result was achieved by immunohistochemistry. Primary lymphoepithelioma-like carcinoma of the skin is a differential diagnosis of lesions with prominent inflammatory infiltrates.

Pigmented Epithelioid Melanocytoma (PEM)/Animal Type Melanoma (ATM): Quest for an Origin. Report of One Unusual Case Indicating Follicular Origin and Another Arising in an Intradermal Nevus

Pigmented epithelioid melanocytoma (PEM) is a tumor encompassing epithelioid blue nevus of Carney complex (EBN of CNC) and was previously termed animal-type melanoma. Histologically PEMs are heavily pigmented spindled and epithelioid dermal melanocytic tumors with infiltrative borders, however, their origin remains unclear. Stem cells for the epidermis and hair follicle are located in the bulge area of the hair follicle with the potential to differentiate into multiple lineages. Multiple cutaneous carcinomas, including follicular cutaneous squamous cell carcinoma (FSCC), are thought to arise from stem cells in the follicular bulge. We present two cases of PEM/ATM in a 63 year-old male on the scalp with follicular origin and a 72 year-old female on the upper back arising in an intradermal nevus. Biopsy of both cases revealed a proliferation of heavily pigmented dermal nests of melanocytes with atypia. The Case 1 tumor was in continuation with the outer root sheath of the hair follicle in the bulge region. Case 2 arose in an intradermal melanocytic nevus. Rare mitotic figures, including atypical mitotic figures, were identified in both cases. We present two cases of PEM, with histologic evidence suggesting two origins: one from the follicular bulb and one from an intradermal nevus.

Acantholytic squamous cell carcinoma is usually associated with hair follicles, not acantholytic actinic keratosis, and is not "high risk": Diagnosis, management, and clinical outcomes in a series of 115 cases

BACKGROUND

Acantholytic squamous cell carcinoma (aSCC) is regarded as a high-risk variant of cutaneous squamous cell carcinoma (SCC). Acantholytic actinic keratosis (aAK) has been regarded as a precursor risk factor for aSCC. However, supporting evidence is limited.

OBJECTIVE

We sought to document clinical features, histologic features, management, and outcomes in a series of aSCC cases.

METHODS

Definitions of aSCC, aAK, and aSCC arising in association with aAK were applied to a consecutive series of aSCC cases. Clinical characteristics and outcomes were obtained from electronic medical records.

RESULTS

Of 115 aSCC cases (103 patients, mean age 71.8 years), actinic keratosis was present in 23% (27/115) but only 7.8% (9/115) exhibited associated aAK. Ten cases (10/115, 9%) fulfilled strict histologic criteria for follicular SCC as previously defined, but 50 of 115 (43%) of our aSCC cases exhibited predominant involvement of follicular epithelium rather than epidermis. Clinical outcome (median follow-up, 36 months) was available in 106 of 115 (92%). One patient experienced regional extension (parotid), and 1 patient experienced a local recurrence (nose). No disease-related metastases or deaths were documented.

LIMITATIONS

This was a single-institution retrospective study from the United States.

CONCLUSIONS

The presence of acantholysis in cutaneous SCC does not specifically confer aggressive behavior, a finding that may inform clinical practice guidelines.

Immunohistochemical findings and differential diagnosis of papillary-type cutaneous verrucous carcinoma of the neck: A case report

Verrucous carcinoma (VC) is a rare subtype of squamous cell carcinoma, with the majority of cases occurring in the oral cavity and genital area. The present study describes a rare case of cutaneous VC of the neck manifesting as a semi-pedunculated multinodular protrusion. Histological analysis revealed thickening of the epidermis and papillary growth. Although cellular atypia was generally mild, a large number of mitoses were observed, of which a small number were abnormal. Additionally, bulbous subepidermal invasion was observed. The lesion was differentiated from papillary squamous cell carcinoma, another rare subtype of squamous cell carcinoma, based on the presence of epidermal verrucous growth and the lack of remarkable nuclear atypia. Benign disorders, including seborrheic keratosis, fibroepithelial polyp, verruca vulgaris and pseudocarcinomatous hyperplasia, were also differentiated from the lesion. Immunohistochemical analysis of cytokeratin (CK)10 expression revealed attenuated staining of the lesion, therefore, anti-CK10 immunohistochemistry may be valuable in the diagnosis of VC.

Unusual growth of upper lip squamous cell carcinoma: a case report

INTRODUCTION

Squamous cell carcinoma is the most common type of lip and oral cavity cancers. In majority of cases it follows quite common course, and after the surgery it does not produce any harm. This case presents unusual and unexpected growth of upper lip squamous cell carcinoma with severe cosmetic problems, and possible health threats.

CASE PRESENTATION

A 46-year-old woman noticed on her upper lip "a spot, the size of a wheat grain", which grew rapidly and reached the size of 0.6 cm during a two-week period. The lesion was red, hard and painful, attached to the skin. It was surgically removed, and primary histopathological finding was follicular keratosis. Recurrent tumor appeared seven days after the operation, with the extreme swelling of the upper lip. The patient was sent to a tertiary hospital, where fungal or bacterial infection was excluded. The change on the patient's upper lip reached the size of 5 × 2 cm, as soft, reddish nodular tumor. Squamous cell carcinoma was diagnosed after the histopathological audit. With the second surgical intervention the tumor was removed and the defect reconstructed.

CONCLUSIONS

Prognosis of this type of tumor, apart from its size and differentiation level, depends on infiltration in tumor-surrounding tissue, perineural and perivascular spread. Therefore, it is always necessary to analyze the removed skin especially on margins.

Squamous cell carcinoma in a psoriasis patient after multiple courses of phototherapy

The authors present a clinical case study of squamous cell carcinoma in a psoriasis patient after 24 courses of phototherapy (22 courses of PUVA therapy and two courses of mid-wavelength ultraviolet therapy (311 nm)). The malignant neoplasm developed against the background of signs of a chronic photodamage of the skin: lentigo, actinic elastosis, diffuse hyperpigmentation, spotty skin pigmentation.

Advanced research on vasculogenic mimicry in cancer

Vasculogenic mimicry (VM) is a brand-new tumour vascular paradigm independent of angiogenesis that describes the specific capacity of aggressive cancer cells to form vessel-like networks that provide adequate blood supply for tumour growth. A variety of molecule mechanisms and signal pathways participate in VM induction. Additionally, cancer stem cell and epithelial-mesenchymal transitions are also shown to be implicated in VM formation. As a unique perfusion way, VM is associated with tumour invasion, metastasis and poor cancer patient prognosis. Due to VM's important effects on tumour progression, more VM-related strategies are being utilized for anticancer treatment. Here, with regard to the above aspects, we make a review of advanced research on VM in cancer.

Desmosomal defects in acantholytic squamous cell carcinomas

BACKGROUND

Acantholytic squamous cell carcinoma (Acantholytic SCC) are epithelial tumors characterized by a loss of cell adhesion between neoplastic keratinocytes. The mechanism underlying loss of cell-cell adhesion in these tumors is not understood.

METHODS

A retrospective analysis of acantholytic SCC (n = 17) and conventional SCC (n = 16, controls not showing acantholysis) was conducted using a set of desmosomal and adherens junction protein antibodies. Immunofluorescence microscopy was used to identify tumors with loss of adhesion protein expression.

RESULTS

The vast majority of acantholytic SCC (89%) showed focal loss of at least one desmosomal cell adhesion protein. Most interestingly, 65% of these tumors lost expression of two or more desmosomal proteins.

CONCLUSIONS

Loss of cell adhesion in acantholytic SCC is most likely linked to the focal loss of desmosomal protein expression, thus providing potential mechanistic insight into the patho-mechanism underlying this malignancy.

Squamous cell carcinoma: variation in dermatoscopic vascular features between well and non-well differentiated tumors

Objective:

Compare the dermatoscopy vascular features of well differentiated with non-well differentiated squamous cell carcinoma (SCC).

Design:

A prospective study of 294 consecutive cases of histopathologically confirmed invasive SCC compared the dermatoscopic vascular features of well to combined moderate and poorly differentiated tumors. These features were recorded live directly from the patients and included: the percentage of pink in the tumor, the presence of branching, serpentine, dot, hairpin, glomerular and linear vessels, and the number of these vessel types present within each tumor. Vessel types were also reviewed by tumor depth in 1 mm increments.

Setting:

Two medical practices in Sydney, Australia.

Patients:

Eighty-six female and 208 male patients (29–95 years old).

Main outcome measure:

Dermatoscopic vascular feature variation between grades of tumor differentiation and tumor depth.

Results:

Of 294 invasive SCCs, 255 (87%) were well differentiated, 32 (11%) were moderately differentiated and 7 (2%) were poorly differentiated. The percentage of pink areas within tumors varied between differentiation grades. The combined group of moderate and poorly differentiated tumors displayed more branching (28%, P<0.001) and serpentine (62%, P<0.005) blood vessels compared to well differentiated tumors (8% and 38%, respectively). Moderate and poorly differentiated tumors displayed larger numbers of vessel types (3.3) compared to well differentiated tumors (2.6, P < 0.01). Branching and serpentine vessels both increased in incidence with increasing tumor depth (p<0.05).

Conclusion:

Grades of tumor differentiation in SCC display varying dermatoscopic vascular features. The incidence of branching and serpentine vessels increases with increasing tumor depth and the shift towards poor differentiation.

Ultraviolet light and skin cancer in athletes

The incidence of melanoma and nonmelanoma skin cancers is increasing worldwide. Ultraviolet light exposure is the most important risk factor for cutaneous melanoma and nonmelanoma skin cancers. Nonmelanoma skin cancer includes basal cell carcinoma and squamous cell carcinoma. Constitutive skin color and genetic factors, as well as immunological factors, play a role in the development of skin cancer. Ultraviolet light also causes sunburn and photoaging damage to the skin.

Molecular markers in cutaneous squamous cell carcinoma

Nonmelanoma skin carcinoma (NMSC) is the most frequent cancer in the USA with over 1.3 million new diagnoses a year; however due to an underappreciation of its associated mortality and growing incidence and its ability to be highly aggressive, the molecular mechanism is not well delineated. Whereas the molecular profiles of melanoma have been well characterized, those for cutaneous squamous cell carcinoma (cSCC) have trailed behind. This importance of the new staging paradigm is linked to the ability currently to better clinically cluster similar biologic behavior in order to risk-stratify lesions and patients. In this paper we discuss the trends in NMSC and the etiologies for the subset of NMSC with the most mortality, cutaneous SCC, as well as where the field stands in the discovery of a molecular profile. The molecular markers are highlighted to demonstrate the recent advances in cSCC.

Loss of Desmocollin 3 in skin tumor development and progression

Desmocollin 3 (DSC3) is a desmosomal cadherin that is required for maintaining cell adhesion in the epidermis as demonstrated by the intra-epidermal blistering observed in Dsc3 null skin. Recently, it has been suggested that deregulated expression of DSC3 occurs in certain human tumor types. It is not clear whether DSC3 plays a role in the development or progression of cancers arising in stratified epithelia such as the epidermis. To address this issue, we generated a mouse model in which Dsc3 expression is ablated in K-Ras oncogene-induced skin tumors. Our results demonstrate that loss of Dsc3 leads to an increase in K-Ras-induced skin tumors. We hypothesize that acantholysis-induced epidermal hyperplasia in the Dsc3 null epidermis facilitates Ras-induced tumor development. Further, we demonstrate that spontaneous loss of DSC3 expression is a common occurrence during human and mouse skin tumor progression. This loss occurs in tumor cells invading the dermis. Interestingly, other desmosomal proteins are still expressed in tumor cells that lack DSC3, suggesting a specific function of DSC3 loss in tumor progression. While loss of DSC3 on the skin surface leads to epidermal blistering, it does not appear to induce loss of cell-cell adhesion in tumor cells invading the dermis, most likely due to a protection of these cells within the dermis from mechanical stress. We thus hypothesize that DSC3 can contribute to the progression of tumors both by cell adhesion-dependent (skin surface) and likely by cell adhesion-independent (invading tumor cells) mechanisms.

Cutaneous squamous cell carcinoma of the head and neck

Cutaneous squamous cell carcinoma of the head and neck is an epidemic that reaches all parts of the world. Making the diagnosis relies on the acumen of the clinician and pathologist. Various pathologic subtypes exist and differ in histology and prognosis. High-risk tumors need aggressive treatment and vigilant surveillance to monitor for recurrence. Large tumors, deep tissue invasion, perineural involvement, recurrence, location in high-risk areas, and immunosuppression are implicated in worsening prognosis. Surgery is the mainstay of treatment with adjuvant radiation therapy as needed for aggressive tumors; however, other modalities are potentially useful for low-risk lesions. The use of Mohs surgery has become increasingly useful and has shown high success rates. Involvement of parotid and neck lymph nodes significantly affects outcomes and the physician should be comfortable with management of this complex disease. This paper examines the diagnosis, pathology, clinical course, and treatment options for cutaneous squamous cell carcinoma of the head and neck.

Histopathological variants of cutaneous squamous cell carcinoma: a review

Nonmelanoma skin cancer (NMSC) is the most common form of cancer in the Caucasian population, with squamous cell carcinoma (SCC) accounting for the majority of NMSC-related metastases and death. While most SCC lesions are indolent tumors with low malignant potential, a wide diversity of SCC subtypes exist, several of which are associated with markedly more aggressive behaviors. Distinguishing these high-risk variants from their counterparts is possible through microscopic analysis, since each subtype possesses unique histopathological features. Early identification of high-risk lesions can allow for more rapid therapeutic intervention, reducing the likelihood of metastasis and death. The authors review specific histopathological features and associated clinical outcomes of the primary subdivisions of SCC.

Molecular regulation of vasculogenic mimicry in tumors and potential tumor-target therapy

“Vasculogenic mimicry (VM)”, is a term that describes the unique ability of highly aggressive tumor cells to express a multipotent, stem cell-like phenotype, and form a pattern of vasculogenic-like networks in three-dimensional culture. As an angiogenesis-independent pathway, VM and/or periodic acid-schiff-positive patterns are associated with poor prognosis in tumor patients. Moreover, VM is resistant to angiogenesis inhibitors. Here, we will review the advances in research on biochemical and molecular signaling pathways of VM in tumors and on potential anti-VM therapy strategy.

Srcasm inhibits Fyn-induced cutaneous carcinogenesis with modulation of Notch1 and p53

Src family tyrosine kinases (SFK) regulate cell proliferation, and increased SFK activity is common in human carcinomas, including cutaneous squamous cell carcinomas (SCC) and its precursors. The elevated SFK activity in cutaneous SCCs was modeled using K14-Fyn Y528F transgenic mice, which spontaneously form punctate keratotic lesions, scaly plaques, and large tumors resembling actinic keratoses, SCC in situ, and SCCs, respectively. Lesional tissue showed increased levels of activated SFKs, PDK1, STAT3, and ERK1/2, whereas Notch1/NICD protein and transcript levels were decreased. p53 levels also were decreased in SCC in situ and SCCs. Increasing Srcasm levels using a K14-Fyn Y528F/K14-Srcasm double transgenic model markedly inhibited cutaneous neoplasia. In contrast, increased expression of a nonphosphorylatable Srcasm mutant maintained the neoplastic phenotype. Increasing Srcasm levels decreased levels of Fyn, activated SFKs, ERK1/2, PDK1, and phospho-STAT3, and increased Notch1/NICD and p53 levels. Analysis of human specimens revealed that levels of Fyn and activated SFKs were elevated in SCCs compared with adjacent nonlesional epidermis. In addition, Notch1 and Srcasm protein and transcript levels were decreased in human SCCs compared with nonlesional epidermis. Therefore, the SCCs produced by the Fyn Y528F mice resemble their human counterparts at the molecular level. K14-Fyn Y528F mice represent a robust model of cutaneous carcinogenesis that manifests precancerous lesions and SCCs resembling human disease. The Fyn/Srcasm signaling nexus modulates activity of STAT3, PDK1, ERK1/2, Notch1, and p53. Further study of Fyn and Srcasm should provide insights into the mechanisms regulating keratinocyte proliferation and skin carcinogenesis.

Histological changes in intra-oral skin flaps

This review outlines the histological features of intra-oral skin flaps and their pathology as encountered in a routine head and neck diagnostic histopathology service. Problems in recognising and interpreting unfamiliar and complex appearances, and areas of diagnostic and prognostic uncertainty, are highlighted.

A Case of Acantholytic Squamous Cell Carcinoma

Acantholytic squamous cell carcinoma is a well-defined variant of squamous cell cancer in which significant portions of the neoplastic proliferation show a pseudoglandular or tubular microscopic pattern. It usually presents as a nodule with various colors, and it is accompanied by scaling, crusting, and ulceration on the sun-exposed areas of older aged individuals. Histologically, the tumor consists of a nodular, epidermal-derived proliferation that forms island-like structures. At least focally or sometimes extensively, the tumor cells shows a loss of cohesion within the central gland-like or tubular spaces. This tumor resembles the structure of eccrine neoplasms, but it is negative for dPAS, CEA and mucicarmine and it is only positive for EMA and cytokeratins. Herein we report a case of acantholytic squamous cell carcinoma that occurred on the face of an 82-year-old woman.

Squamous cell carcinomas with single cell infiltration: a potential diagnostic pitfall and the utility of MNF116 and p63

Numerous variants of squamous cell carcinoma (SCC) have been described. We recently encountered four examples of SCC composed primarily of single, atypical cells that were cytokeratin (CK) MNF116-positive and p63-positive. One case was particularly difficult to diagnose as the single cells were obscured by a dense inflammatory infiltrate. We have also noted similar single cell infiltration toward the periphery of four additional cases of more typical SCC. These foci resemble the single tumor cells that may infiltrate at the borders of spindle cell and desmoplastic SCCs. CK MNF116 and p63 were useful in identifying each of these neoplasms. This single--cell pattern of SCC can easily be misdiagnosed, and CK MNF116 and/or p63 are diagnostically helpful in recognizing it.

Lymphoepithelioma-like carcinoma arising in the scar from a previously excised basal cell carcinoma

We report a case of a primary lymphoepithelioma-like carcinoma of the skin (LELCS) associated with scar from a previous excision of basal cell carcinoma. The patient was a 68-year-old female with a 3.0 mm skin-colored pearly papule on her forehead that developed over 2-3 months. The patient had a history of a basal cell carcinoma in the same location, which was completely excised 1 year earlier. A biopsy and subsequent excision of the tumor were performed. The tumor consisted of small islands of large pleomorphic mitotically active epithelioid cells surrounded by a very dense lymphoplasmacytic infiltrate. The tumor was associated with dermal scar. There was no connection of tumor with the unremarkable epidermis. Immunohistochemical examination showed that the epithelioid tumor cells were positive for pan-cytokeratin and epithelial membrane antigen, supporting the morphologic impression of LELCS. The lesion was negative for Epstein-Barr virus. Retrospective review of the original excision specimen confirmed the diagnosis of an ordinary basal cell carcinoma. Forty-five cases of LELCS have been reported to date. We report the first case of LELCS to arise in the scar from an excision of a cutaneous malignancy.