Basaloid squamous cell carcinoma of the skin

A Rare Case of Primary Cutaneous Basaloid Squamous Cell Carcinoma of the Finger

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An unusual case of pilonidal p16 positive squamous cell carcinoma-a case report

Basaloid squamous cell carcinoma (BSCC) is a rare and aggressive variant of squamous cell carcinoma. It is commonly seen in the oropharynx and strongly associated with p16-expressivity and high-risk human papilloma virus (HPV). We report the first case of primary cutaneous p16-positive BSCC in an elderly woman, with a background of chronic inverse psoriasis of the natal cleft. P16-expressivity is a common surrogate marker for oncogenic HPV16, routinely tested for oropharyngeal/anogenital squamous cell carcinoma. This is not routinely done for primary cutaneous disease. Pilonidal disease is uncommon in the elderly population, and malignant transformation is rarer still. Surgical resection is considered the mainstay of treatment for primary cutaneous BSCC, however due to this patient's broad distribution of cutaneous field change and p16-expressivity, she was effectively treated with primary radiotherapy. This is a unique case of malignant transformation of pilonidal disease in an atypical demographic, with a rare/aggressive disease variant.

Assessment of Basal Cell Carcinoma Using Dermoscopy and High Frequency Ultrasound Examination

Basal cell carcinoma (BCC) is the most common form of cutaneous neoplasia in humans, and dermoscopy may provide valuable information for histopathological classification of BCC, which allows for the choice of non-invasive topical or surgical therapy. Similarly, dermoscopy may allow for the identification of incipient forms of BCC that cannot be detected in clinical examination. The importance of early diagnosis using the dermoscopy of superficial BCC forms is proven by the fact that despite their indolent clinical appearance, they can be included in high-risk BCC forms due to the rate of postoperative recurrence. Nodular pigmentary forms of BCCs present ovoid gray-blue nests or multiple gray-blue dots/globules associated with arborized vessels, sometimes undetectable on clinical examination. The management of BCC depends on this, as pigmentary forms have been shown to have a poor response to photodynamic therapy. High frequency ultrasound examination (HFUS) aids in the diagnosis of BCC with hypoechoic tumour masses, as well as in estimating tumour size (thickness and diameter), presurgical margin delineation, and surgical planning. The examination is also useful for determining the invasion of adjacent structures and for studying local recurrences. The use of dermoscopy in combination with HFUS allows for optimisation of the management of the oncological patient.

Metastatic Basal Cell Carcinoma: An Unexpected Diagnosis in a Young Patient With Back Pain

ABSTRACT

Basal cell carcinoma (BCC) portends a notoriously favorable prognosis in most patients with morbidity limited to localized destruction and recurrence. Metastatic BCC (mBCC) is an unexpected outcome affecting less than 1% of patients with a known primary lesion and predominantly involves regional lymph nodes. Reports of isolated bone involvement and spinal cord compression are rare. In the cases we identified in the literature, patients presented with massive primary lesions on the trunk that had been present for years and that were often still present at the time of diagnosis. Additionally, histology of distant metastatic lesions typically reveals aggressive subtypes. Herein, we report a case of mBCC in a patient with a history of BCC involving the cheek; the lesion was excised more than 10 years ago. He was referred to our institution for acutely worsening back pain and multifocal neurologic deficits. Clinical symptoms and radiographic findings demonstrated isolated bone involvement, with multiple lytic bone lesions and spinal cord compression noted on imaging studies. Biopsy revealed nests of small basaloid cells with peripheral palisading and immunohistochemical staining consistent with the unexpected diagnosis of mBCC, nodular subtype. Our case illustrates that a historically resected primary lesion may cause distant metastasis after a decade and that nonaggressive subtypes can also be implicated. We also provide insight into the potential pathogenesis of this manifestation.

PD-1 inhibitor therapy of basal cell carcinoma with pulmonary metastasis

Basal cell carcinoma (BCC) may be challenging to differentiate from basaloid squamous cell carcinoma (bSCC), both clinically and histologically. BCC constitutes one of the most common tumours and metastatic behaviour is extremely rare. In contrast, bSCC is a rare entity with an increased propensity for distant metastasis. If these conditions develop into inoperable metastatic disease, the therapeutic alternatives are different, but the use of PD-1 inhibitors may be a valid option for both. Here, we report a case with complex histology with a component initially classified as bSCC with lung metastases and treated with the PD-1 inhibitor cemiplimab resulting in radiological and clinical responses. Re-examination of the lung biopsy using routine histomorphology in combination with immunohistochemical staining for cytokeratin 14, cytokeratin17 and BerEp4 has, however, revealed a histopathological pattern of BCC, which is in concordance with a similar analysis of the cutaneous primary tumour in the face that the patient underwent surgery for more than 5 years earlier.

Metastatic Basal Cell Carcinoma of the Skin: A Comprehensive Literature Review, Including Advances in Molecular Therapeutics

Basal cell carcinoma (BCC) of the skin is the most common type of malignant human tumor. In Europe, the incidence of BCC ranges from 44.6 to 128 cases per 100,000 inhabitants annually, whereas in the United States, the yearly incidence rate ranges between 500 and 1500. The global incidence has been calculated to be as high as 10 million cases of BCC per year. There are 2 main clinical patterns of BCC-the familial BCC in basal cell nevus syndrome and sporadic BCC. The etiology of cutaneous BCC is usually the result of the interaction between solar ultraviolet radiation and genetic factors. Somatic or germline mutations in the effector components of the hedgehog signaling pathway (ie, PTCH1, PTCH2, SMO or SUFU genes) are responsible for ∼90% of the cases of both sporadic and familial BCC, all causing a constitutive activation of the hedgehog pathway. Cutaneous BCC very rarely metastasizes, and diagnosis in metastatic sites can be very difficult. Metastatic BCC has weakly effective therapeutic options with a poor prognosis until few years ago. In 2012, small-molecule therapies, involving inactivation of the hedgehog signaling pathway, and capable of reducing tumor growth and progression have been introduced into clinical practice for advanced (locally advanced or metastatic) BCC. We performed a comprehensive literature review on metastatic BCC and found at least 915 cases reported to date. In addition, we extensively discussed the differential diagnosis of metastatic BCC, and outlined the advances in clinical therapeutics involving these small molecules.

Cutaneous HPV16 and p16 Positive Basaloid Squamous Cell Carcinoma with Brain Metastasis: A Case Report

Basaloid squamous cell carcinoma is an infiltrative and aggressive variant of squamous cell carcinoma with basaloid features. Primary skin-derived basaloid squamous cell carcinoma is rare. Basaloid squamous cell carcinoma is commonly observed in the oropharyngeal and anogenital regions and is associated with high-risk human papillomavirus. We report a case of primary basaloid squamous cell carcinoma overlying the right scapula with metastasis to the regional lymph nodes and brain despite surgical resection and adjuvant chemoradiation. Histopathologic investigations of high-risk cutaneous squamous cell carcinoma do not routinely involve human papillomavirus testing. In contrast, oncogenic human papillomavirus and p16 are screened in head and neck squamous cell carcinoma for prognostication. Since the patient presented with an aggressive variant of squamous cell carcinoma and distal metastasis despite standard therapies, human papillomavirus testing was performed. P16, a surrogate marker for human papillomavirus infection and specifically HPV16 was identified in the tumor. This is a unique report of HPV16 in primary cutaneous basaloid squamous cell carcinoma with distal brain metastasis.

Metastatic Cutaneous Basal Cell Carcinoma: Report of 2 Cases Preceding the Hedgehog Pathway Antagonists Era

Basal cell carcinoma (BCC) of the skin is the most common type of malignant human tumor. However, metastatic BCC is a very rare event with weakly effective therapeutic options and a poor prognosis, until a few years ago. In 2012, small-molecule therapies, capable of inactivating the hedgehog signaling pathway and thus reducing tumor growth and progression, were introduced into clinical practice for the treatment of patients with advanced BCC. We present retrospectively 2 personal cases of metastatic BCC of the skin, from the premolecular therapy era, from primary tumors that arose years before in the head and neck area. The former case occurred in a 45-year-old woman with a history of recurrent BCC of the retroauricular skin who eventually died due to diffuse metastatic spread. The latter case concerned a 70-year-old man also with a history of recurrent BCC of the nasal-perinasal skin who developed multiple subcutaneous and lymph node metastases in the neck. In both cases, the diagnoses were based on biopsies of the metastatic sites. The first patient died 5 months after the diagnosis of metastatic disease, while the second was alive and disease-free 2 years after neck lymph node dissection and external radiation therapy, and then lost to follow-up. We extensively discuss several tumor entities with basal or basaloid features that may enter the differential diagnosis with BCC in metastatic sites. In addition, we briefly summarize the advances in clinical therapeutics using small molecules, which are now an integral part of the treatment of such advanced BCC cases.

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.

A Limited Immunohistochemical Panel to Distinguish Basal Cell Carcinoma of Cutaneous Origin From Basaloid Squamous Cell Carcinoma of the Head and Neck

Head and neck carcinomas with basaloid features can be diagnostically challenging. A common diagnostic issue is the distinction between a basaloid squamous cell carcinoma (bSCC) and a basal cell carcinoma (BCC) of cutaneous origin. This is particularly true in small biopsy specimens where classic architectural and histologic features may be difficult to appreciate. A specific diagnosis is essential because of significant differences in clinical outcome and therapeutic management. Ten resection cases of bSCC and BCC of the head and neck were selected based on primary location and the classic morphologic features that characterize these 2 entities. The following immunohistochemical markers were evaluated: epithelial membrane antigen (EMA), Ber-EP4, CD44, Bcl2, androgen receptor, SOX2, and p16. The strongest statistically significant differences in staining patterns were for EMA, p16, and SOX2. EMA was positive in all bSCCs and negative in all BCCs. SOX2 was positive in all bSCCs and in only 3 out of 10 BCCs. Staining was weak and peripheral in the SOX2-positive BCCs. p16 was positive in 8 out of 10 bSCCs and negative in all BCCs. We conclude that bSCC and BCC of the head and neck can be readily distinguished by a limited panel consisting primarily of EMA, and supported by SOX2 and p16.

Sentinel lymph node metastasis in primary cutaneous basosquamous carcinoma. A cross-sectional study

BACKGROUND AND OBJECTIVES

Basosquamous carcinoma (BSC) is a rare, biologically aggressive tumor. This cross-sectional study aims to define risk factors for subclinical nodal metastasis in primary BSC, and identify the patients who would benefit from routine sentinel node biopsy (SLNB) as part of the initial management.

METHODS

A total of 142 patients, with histologically proven BSC without palpable lymph nodes, underwent SLNB after the initial excision. Clinicopathological features and demographics were analyzed between the patients with detected micrometastasis (SLNM) and those with negative SLN.

RESULTS

In 7.7% patients, subcapsular and <0.1 mm SLNM were found. The frequency of SLNM was 0.9%, 11.8%, and 80.0% in patients with maximum lesion diameter ≤ 2 cm, 2.1-3.0 cm and >3.0 cm, respectively (P < 0.001) and was strongly associated with perineural (P < 0.001; OR = 26.46, 95% CI = 5.62-124.52) and lymphatic invasion (P < 0.001; OR = 17.35, 95% CI = 4.44-67.91). Within 18-84 months, no recurrence or metastasis were observed in SLNM positive patients. False negative SLNB rate of 15.4% was recorded.

CONCLUSION

Cutaneous BSC is associated with early nodal metastatic potential. Tumor size >2 cm, lymphatic and perineural invasion are significant determinants for SLN micrometastasis. In the absence of palpable lymphadenopathy, wide resection and SLNB with long-term follow-up are highly recommended in these patients.

Interpretation and Relevance of Advanced Technique Results

Advanced techniques in the field of diagnostic microbiology have made amazing progress over the past 25 years due largely to a technological revolution in the molecular aspects of microbiology [1, 2]. In particular, rapid molecular methods for nucleic acid amplification and characterization combined with automation in the clinical microbiology laboratory as well as user-friendly software and robust laboratory informatics systems have significantly broadened the diagnostic capabilities of modern clinical microbiology laboratories. Molecular methods such as nucleic acid amplification tests (NAATs) rapidly are being developed and introduced in the clinical laboratory setting [3, 4]. Indeed, every section of the clinical microbiology laboratory, including bacteriology, mycology, mycobacteriology, parasitology, and virology, has benefited from these advanced techniques. Because of the rapid development and adaptation of these molecular techniques, the interpretation and relevance of the results produced by such molecular methods continues to lag behind. The purpose of this chapter is to review, update, and discuss the interpretation and relevance of results produced by these advanced molecular techniques.

Cutaneous Squamous Cell Carcinoma: Review of the Eighth Edition of the American Joint Committee on Cancer Staging Guidelines, Prognostic Factors, and Histopathologic Variants

Cutaneous squamous cell carcinoma is the second most common form of nonmelanoma skin cancer after basal cell carcinoma and accounts for the majority of nonmelanoma skin cancer-related deaths. In 2017, the American Joint Committee on Cancer revised the staging guidelines of cutaneous squamous cell carcinoma to reflect recent evidence concerning high-risk clinicopathologic features. This update reviews the literature on prognostic features and staging, including the eighth edition of the American Joint Committee on Cancer Staging Manual. A wide range of histopathologic variants of cutaneous squamous cell carcinoma exists, several of which are associated with aggressive behavior. A review of cutaneous squamous cell carcinoma variants, emphasizing diagnostic pitfalls, immuhistochemical findings and prognostic significance, is included. Of note, the eighth edition of the American Joint Committee on Cancer Staging Manual refers to squamous cell carcinoma of the head and neck only.

Histopathologic pitfalls of Mohs micrographic surgery and a review of tumor histology

Mohs micrographic surgery is a specialized subset of staged surgical excisions with each subsequent stage being driven largely by the histologic findings of the previous stage. Therefore, it is imperative that histologic analysis is performed in an accurate manner. Frozen section and tissue flattening is a crucial step in Mohs surgery. Frozen sections introduce certain artifacts and these artifacts must be interpreted in the correct context. Basal and squamous cell carcinomas are the most common tumors encountered in Mohs micrographic surgery, and their histopathology is also associated with certain "pitfalls". Basal cell carcinoma should be distinguished from hair follicles, folliculocentric basaloid proliferations, poromas, nevus sebaceous, desmoplastic trichoepitheliomas, and spiradenomas, to name but a few histologic entities. Similarly, squamous cell carcinoma should be distinguished from hypertrophic actinic keratoses, pseudoepitheliomatous hyperplasia, sebaceous carcinoma, and microcystic adnexal carcinoma. In addition, there are numerous subtypes of basal cell and squamous carcinomas that the Mohs surgeon should be aware of due to differences in the biologic behavior of these tumors. This review presents a number of the common histologic pitfalls of Mohs micrographic surgery and a review of tumor histology.

Basal cell carcinoma vs basaloid squamous cell carcinoma of the skin: an immunohistochemical reappraisal

Typical cutaneous basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are morphologically dissimilar. It is well known, however, that poorly differentiated SCC may assume a basaloid phenotype, complicating the histologic distinction between these 2 neoplasms. Selected immunohistochemical stains have been used in the past to aid in that differential diagnosis. In the current study, additional markers were evaluated to determine whether they would be helpful in that regard. Twenty-nine cases of metatypical (squamoid) BCC (MBCC) and 25 examples of basaloid SCC (BSCC) were studied using the antibodies Ber-EP4 and MOC-31 as well as a plant lectin preparation from Ulex europaeus I (UEA-1). The resulting immunostains were interpreted independently by 3 pathologists, and the results showed that MBCCs demonstrated strong and diffuse staining for Ber-EP4 (25/29) and MOC-31 (29/29). In contrast, BSCCs tended to be only sporadically reactive for both markers (4/25 and 1/25 cases, respectively). Labeling for UEA-1 was observed in almost all BSCCs (24/25), but only 6 of 29 cases of MBCC showed limited, focal staining with that lectin. These data suggest that MOC-31 is a useful marker in the specified differential diagnosis, especially when used together with UEA-1.

The incidence and risk factors of metastasis for cutaneous squamous cell carcinoma--implications on the T-classification system

Cutaneous squamous cell carcinoma (cSCC) constitutes the most common cancer capable of metastasis. While the latest version of the American Joint Committee on Cancer guidelines represents a significant step forward in accurate staging of cSCC, several proven independent risk factors remain excluded. We review the current literature on the incidence and proven independent risk factors of metastasis for cSCC and proposes their full inclusion in the staging system for primary lesions.

The dermatoscopic universe of basal cell carcinoma

Following the first descriptions of the dermatoscopic pattern of basal cell carcinoma (BCC) that go back to the very early years of dermatoscopy, the list of dermatoscopic criteria associated with BCC has been several times updated and renewed. Up to date, dermatoscopy has been shown to enhance BCC detection, by facilitating its discrimination from other skin tumors and inflammatory skin diseases. Furthermore, upcoming evidence suggests that the method is also useful for the management of the tumor, since it provides valuable information about the histopathologic subtype, the presence of clinically undetectable pigmentation, the expansion of the tumor beyond clinically visible margins and the response to non-ablative treatments. In the current article, we provide a summary of the traditional and latest knowledge on the value of dermatoscopy for the diagnosis and management of BCC.

Dermoscopy of basosquamous carcinoma

BACKGROUND

Basosquamous carcinoma (BSC) is a rare and potentially aggressive tumour, characterized by clinical and pathological features of both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). It is reported to have a nonspecific clinical presentation, which makes naked-eye diagnosis a challenge.

OBJECTIVES

To describe the dermoscopic patterns of BSC, which may facilitate early diagnosis and accurate management.

METHODS

This was a retrospective evaluation of clinical and dermoscopic images of histopathologically proven BSC, collected from skin cancer centres in Australia (Perth), Greece (Thessaloniki) and Italy (Naples, Reggio Emilia).

RESULTS

Twenty-two tumours were included in the study. Our analysis revealed that the dermoscopic pattern of BSC comprises BCC-related criteria, as well as features that are known to characterize invasive SCC. The most frequently detected criteria were: unfocused (peripheral) arborizing vessels (73%), keratin masses (73%), white structureless areas (73%), superficial scale (68%), ulceration or blood crusts (68%), white structures (64%), blue-grey blotches (59%) and blood spots in keratin masses (55%). Notably, all but one of the tumours exhibited at least one BCC-related plus one SCC-related dermoscopic feature.

CONCLUSIONS

BSC appears to have overlapping dermoscopic features of BCC and invasive SCC, and detection of at least one dermoscopic criterion of both BCC and SCC should raise suspicion for the tumour. Appreciation of the dermoscopic patterns of BSC might assist in the timely and accurate diagnosis and subsequent optimal management of this unusual and potentially metastatic skin tumour.

BerEp4, Cytokeratin 14, and Cytokeratin 17 Immunohistochemical Staining Aid in Differentiation of Basaloid Squamous Cell Carcinoma From Basal Cell Carcinoma With Squamous Metaplasia

Context.—Basaloid squamous cell carcinoma (bSCC) is an uncommon variant of squamous cell carcinoma, which may overlap histologically with basal cell carcinoma with squamous metaplasia (BCCm).

Objective.—To aid in the differentiation of these neoplasms using immunohistochemical staining because of the worse prognosis associated with bSCC.

Design.—Using immunohistochemical techniques, we investigated BerEp4, cytokeratin 17 (CK17), and cytokeratin 14 (CK14) protein expression in 25 cases of bSCC (8 cutaneous [32%], 12 aerodigestive tract [48%], and 5 lymph node metastases [20%]) and 43 cases of BCCm (39 cutaneous [91%], and 4 metastases [9%]). An immunoreactivity score was assigned using the percentage of tumor cells staining and the pattern of expression. Interobserver agreement for 2 independent pathologists was assessed using a κ coefficient.

Results.—The mean percentage of staining was significantly higher in BCCm, compared with bSCC (BerEp4, P = .006; CK17, P &lt; .001; CK14, P &lt; .001; unpaired t test), with 58% of BCCm cases (25 of 43) displaying diffuse staining for all markers, and nearly all (98%; 42 of 43) displaying diffuse staining for CK17 and CK14. In contrast, no bSCC cases (0%) displayed diffuse staining for all 3 markers, and only 8% (2 of 25) displayed diffuse staining for CK17 and CK14. High interobserver agreement was determined.

Conclusions.—BerEp4 alone is unreliable for differentiation between BCCm and bSCC, and the addition of either CK14 or CK17 will augment the sensitivity and negative predictive value of BerEp4 staining in BCCm and bSCC diagnosis.

Epithelial stem cell mutations that promote squamous cell carcinoma metastasis

Squamous cell carcinomas (SCCs) originate in stratified epithelia, with a small subset becoming metastatic. Epithelial stem cells are targets for driver mutations that give rise to SCCs, but it is unknown whether they contribute to oncogenic multipotency and metastasis. We developed a mouse model of SCC by targeting two frequent genetic mutations in human SCCs, oncogene Kras(G12D) activation and Smad4 deletion, to mouse keratin 15-expressing (K15+) stem cells. We show that transgenic mice developed multilineage tumors, including metastatic SCCs. Among cancer stem cell-enriched (CSC-enriched) populations, those with increased side population (SP) cells correlated with epithelial-mesenchymal transition (EMT) and lung metastasis. We show that microRNA-9 (miR-9) contributed to SP expansion and metastasis, and miR-9 inhibition reduced the number of SP cells and metastasis. Increased miR-9 was detected in metastatic human primary SCCs and SCC metastases, and miR-9-transduced human SCC cells exhibited increased invasion. We identified α-catenin as a predominant miR-9 target. Increased miR-9 in human SCC metastases correlated with α-catenin loss but not E-cadherin loss. Our results demonstrate that stem cells with Kras(G12D) activation and Smad4 depletion can produce tumors that are multipotent and susceptible to EMT and metastasis. Additionally, tumor initiation and metastatic properties of CSCs can be uncoupled, with miR-9 regulating the expansion of metastatic CSCs.

HPV genotypes in paraffin sections of non-cervical squamous cell carcinoma in Qingdao of China

Human papillomaviruses (HPVs) are the cause of cervical cancer and possibly a subset of squamous cell carcinomas (SCCs) in other sites. However, the prevalence and distribution of HPV subtypes remain unclear. In the present study, we collected and analyzed 511 paraffin sections of non-cervical SCC from patients in Qingdao, China, for the presence of HPV using polymerase chain reaction (PCR). We identified that 55.77% (285/511) of the samples were positive for HPV infection. There was a significant association between HPV type and the different sites of SCC. An association between HPV-positive cases and tobacco, alcohol, age and tumor differentiation was demonstrated. The information provided by this study may be important for further investigation into the association between HPV and SCC. High-risk HPV subtypes were associated with the malignant degree of SCC. This study provided a theoretical basis for the preventative treatment of non-cervical SCC using HPV vaccines.

Interpretation and Relevance of Advanced Technique Results

Advanced techniques in the field of diagnostic microbiology have made amazing progress over the past two decades due largely to a technological revolution in the molecular aspects of microbiology [1, 2]. In particular, rapid molecular methods for nucleic acid amplification and characterization combined with automation and user-friendly software have significantly broadened the diagnostic capabilities of modern clinical microbiology laboratories. Molecular methods such as nucleic acid amplification tests (NAATs) rapidly are being developed and introduced in the clinical laboratory setting. Indeed, every section of the clinical microbiology laboratory, including bacteriology, mycology, mycobacteriology, parasitology, and virology, have benefited from these advanced techniques. Because of the rapid development and adaptation of these molecular techniques, the interpretation and relevance of the results produced by such molecular methods has lagged somewhat behind. The purpose of this chapter is to review and discuss the interpretation and relevance of results produced by these advanced molecular techniques. Moreover, this chapter will address the “myths” of NAATs, as these myths can markedly influence the interpretation and relevance of these results.

Metastatic basal cell carcinoma of the posterior neck: case report and review of the literature

Although primary basal cell carcinoma (BCC) represents an extremely common malignancy, metastases derived from BCC are exceedingly rare. The prognosis for metastatic BCC is poor, and little consensus exists regarding predictive factors or optimal treatment strategies. Here, we present the case of a 63-year-old man with BCC of the neck who subsequently developed multiple metastases to subcutaneous tissue, lymph nodes, and the parotid gland. Risk factors and clinical features of metastatic BCC are reviewed, as is the relationship of histopathologic subtype to metastatic behavior. Current chemotherapeutic and targeted therapies also are discussed in the context of recent advances in molecular biology.