The difficulty with measuring the largest melanoma tumour diameter in sentinel lymph nodes.

Identification of sentinel node (SN) metastases can set the adjuvant systemic therapy indication for stage III melanoma patients. For stage IIIA patients, a 1.0 mm threshold for the largest SN tumour diameter is used. Therefore, uniform reproducible measurement of its size is crucial. At present, the number of deposits or their microanatomical sites are not part of the inclusion criteria for adjuvant treatment. The goal of the current study was to show examples of the difficulty of measuring SN melanoma tumour diameter and teach how it should be measured. Histopathological slides of SN-positive melanoma patients were retrieved using the Dutch Pathology Registry (PALGA). Fourteen samples with the largest SN metastasis around 1.0 mm were uploaded via tele-pathology and digitally measured by 12 pathologists to reflect current practice of measurements in challenging cases. Recommendations as educational examples were provided. Microanatomical location of melanoma metastases was 1 subcapsular, 2 parenchymal and 11 combined. The smallest and largest difference in measurements were 0.24 mm and 4.81 mm, respectively. 11/14 cases (78.6%) showed no agreement regarding the 1.0 mm cut-off. The median discrepancy for cases ≤5 deposits was 0.5 mm (range 0.24-0.60, n=3) and 2.51 mm (range 0.71-4.81, n=11) for cases with ≥6 deposits. Disconcordance in measuring SN tumour burden is correlated with the number of deposits. Awareness of this discordance in challenging cases, for example, cases with multiple small deposits, is important for clinical management. Illustrating cases to reduce differences in size measurement are provided.

Cumulative incidence and timing of subsequent cutaneous squamous cell carcinomas stratified for patients with organ transplantation and hematologic malignancies: A nationwide cohort study.

BACKGROUND: There is lack of nationwide data on the cumulative incidence and timing of subsequent cutaneous squamous cell carcinomas (cSCCs) among patients with a first cSCC. OBJECTIVE: To investigate the cumulative incidence and timing of subsequent cSCCs. METHODS: Patients with a first cSCC in 2007/2008 from the Netherlands Cancer Registry were linked to the Netherlands Pathology Registry for subsequent cSCCs and the Netherlands Organ Transplant Registry. Cumulative incidence function curves were calculated for subsequent cSCCs and stratified for immune status. RESULTS: Among the 12,345 patients, second to sixth cSCC occurred in 4325, 2010, 1138, 739, and 501 patients, with median time intervals of 1.4, 1.2, 0.9, 0.6, and 0.5 years after the previous cSCC, respectively. The cumulative incidence of a subsequent cSCC at 5 years increased from 28% to 67% for the second to sixth cSCC. For solid organ transplant recipients, the cumulative incidences increased from 74% to 92% and from 41% to 64% for patients with hematologic malignancy. LIMITATIONS: Only histopathologically confirmed cSCCs were included. CONCLUSION: The risk of a subsequent cSCC steeply rises with the number of prior cSCCs and immune status, while the time interval decreases. This can support more informed decisions about follow-up management.

Clinical evaluation of the clinicopathologic and gene expression profile (CP-GEP) in patients with melanoma eligible for sentinel lymph node biopsy: A multicenter prospective Dutch study.

Sentinel lymph node biopsy (SLNB) is recommended for patients with >pT1b cutaneous melanoma, and should be considered and discussed with patients diagnosed with pT1b cutaneous melanoma for the purpose of staging, prognostication and determining eligibility for adjuvant therapy. Previously, the clinicopathologic and gene expression profile (CP-GEP, Merlin Assay®) model was developed to identify patients who can forgo SLNB because of a low risk for sentinel node metastasis. The aim of this study was to evaluate the clinical use and implementation of the CP-GEP model in a prospective multicenter study in the Netherlands. Both test performance and feasibility for clinical implementation were assessed in 260 patients with T1-T4 melanoma. The CP-GEP model demonstrated an overall negative predictive value of 96.7% and positive predictive value of 23.7%, with a potential SLNB reduction rate of 42.2% in patients with T1-T3 melanoma. With a median time of 16 days from initiation to return of test results, there was sufficient time left before the SLNB was performed. Based on these outcomes, the model may support clinical decision-making to identify patients who can forgo SLNB in clinical practice.

Personalised decision making to predict absolute metastatic risk in cutaneous squamous cell carcinoma: development and validation of a clinico-pathological model.

Background: Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer, affecting more than 2 million people worldwide yearly and metastasising in 2-5% of patients. However, current clinical staging systems do not provide estimates of absolute metastatic risk, hence missing the opportunity for more personalised treatment advice. We aimed to develop a clinico-pathological model that predicts the probability of metastasis in patients with cSCC. Methods: Nationwide cohorts from (1) all patients with a first primary cSCC in The Netherlands in 2007-2008 and (2) all patients with a cSCC in 2013-2015 in England were used to derive nested case-control cohorts. Pathology records of primary cSCCs that originated a loco-regional or distant metastasis were identified, and these cSCCs were matched to primary cSCCs of controls without metastasis (1:1 ratio). The model was developed on the Dutch cohort (n = 390) using a weighted Cox regression model with backward selection and validated on the English cohort (n = 696). Model performance was assessed using weighted versions of the C-index, calibration metrics, and decision curve analysis; and compared to the Brigham and Women's Hospital (BWH) and the American Joint Committee on Cancer (AJCC) staging systems. Members of the multidisciplinary Skin Cancer Outcomes (SCOUT) consortium were surveyed to interpret metastatic risk cutoffs in a clinical context. Findings: Eight out of eleven clinico-pathological variables were selected. The model showed good discriminative ability, with an optimism-corrected C-index of 0.80 (95% Confidence interval (CI) 0.75-0.85) in the development cohort and a C-index of 0.84 (95% CI 0.81-0.87) in the validation cohort. Model predictions were well-calibrated: the calibration slope was 0.96 (95% CI 0.76-1.16) in the validation cohort. Decision curve analysis showed improved net benefit compared to current staging systems, particularly for thresholds relevant for decisions on follow-up and adjuvant treatment. The model is available as an online web-based calculator (https://emc-dermatology.shinyapps.io/cscc-abs-met-risk/). Interpretation: This validated model assigns personalised metastatic risk predictions to patients with cSCC, using routinely reported histological and patient-specific risk factors. The model can empower clinicians and healthcare systems in identifying patients with high-risk cSCC and offering personalised care/treatment and follow-up. Use of the model for clinical decision-making in different patient populations must be further investigated. Funding: PPP Allowance made available by Health-Holland, Top Sector Life Sciences & Health, to stimulate public-private partnerships.

Hedgehog pathway mutations are involved in the pathogenesis of plaque-type "trichoblastoma": A report of two cases.

We present two cases of plaque-type trichoblastoma with atypical foci. A rare variant of trichoblastoma is the plaque variant, which is characterized by poor circumscription and locally infiltrative growth pattern. These lesions mostly require multiple stages of Mohs micrographic surgery. Debate still exists whether this variant should be considered as a benign entity or as "low-grade" malignant counterpart of trichoblastoma. In this report we describe two cases of plaque-type trichoblastoma with atypical foci, which harbored somatic mutations in the Hedgehog pathway, thus should be acknowledged as intermediate malignancies. In addition, extensive molecular workup of both the trichoblastic and atypical component in sequential lesions in the same patient was performed.

Ambiguous melanocytic lesions: A retrospective cohort study of incidence and outcome of melanocytic tumor of uncertain malignant potential (MELTUMP) and superficial atypical melanocytic proliferation of uncertain significance (SAMPUS) in the Netherlands.

BACKGROUND: Melanocytic tumor of uncertain malignant potential (MELTUMP) and superficial atypical melanocytic proliferation of uncertain significance (SAMPUS) are descriptive and provisional terms for melanocytic tumors with ambiguous histopathological features that are not easily classified as either benign or malignant. OBJECTIVE: To investigate the incidence and clinical outcome of MELTUMP and SAMPUS in the Netherlands. METHODS: In this retrospective cohort study, we reviewed all diagnoses of MELTUMP and SAMPUS from the Dutch Nationwide Pathology Databank from 1991 to October 1, 2021. Clinical outcome was studied for cases diagnosed until October 1, 2018. RESULTS: A total of 1685 MELTUMP and 1957 SAMPUS were identified with an annual incidence of 150 to 300 cases. Metastatic behavior was seen in 0.7% of all initially diagnosed MELTUMP. All SAMPUS remained free of metastases. LIMITATIONS: Reassessment of pathology slides and confirmation of clonality between primary and metastatic lesions remained outside the scope of this study. CONCLUSION: Despite the 'uncertainty' in the nomenclature, our results demonstrate a low malignant potential for MELTUMP and no malignant potential for SAMPUS. We emphasize the importance of consultation for ambiguous melanocytic lesions and to limit the MELTUMP/SAMPUS terminology to legitimately uncertain or unclassifiable cases.

A Scoping Review and Population Study Regarding Prevalence and Histopathology of Juvenile Vulvar Melanocytic Lesions. A Recommendation.

Cases of vulvar melanocytic lesions in juveniles are rarely reported. We analyze the evidence regarding vulvar melanocytic lesions in juveniles with or without vulvar lichen sclerosus to help decision making by clinicians and pathologists. A scoping review on vulvar melanocytic lesions with or without vulvar lichen sclerosus, including malignant vulvar melanomas, in females up to age 18 years was performed. In addition, the histopathology records of the cohort of all such lesions in The Netherlands from 1991 through 2020 were investigated, and a structured analysis of tissue samples of the subset of cases with lichen sclerosus was performed. The literature study performed confirms that vulvar melanomas in juveniles are extremely rare and that published case reports are often disputed. In The Netherlands, there are no cases of malignant vulvar melanomas up to age 18 years recorded from 1991 through 2020. Atypical histopathological features are often found in biopsies of vulvar nevi in juveniles, especially with concomitant lichen sclerosus, confirming earlier case studies in the literature. We conclude that even with atypical findings, vulvar melanocytic lesions in juveniles have a benign course. To avoid unnecessary and possibly mutilating procedures, we advise referral to an expert center and adaption of existing guidelines for vulvar melanocytic lesions in juveniles.

Using a Clinicopathologic and Gene Expression (CP-GEP) Model to Identify Stage I-II Melanoma Patients at Risk of Disease Relapse.

Background: The current standard of care for patients without sentinel node (SN) metastasis (i.e., stage I−II melanoma) is watchful waiting, while >40% of patients with stage IB−IIC will eventually present with disease recurrence or die as a result of melanoma. With the prospect of adjuvant therapeutic options for patients with a negative SN, we assessed the performance of a clinicopathologic and gene expression (CP-GEP) model, a model originally developed to predict SN metastasis, to identify patients with stage I−II melanoma at risk of disease relapse. Methods: This study included patients with cutaneous melanoma ≥18 years of age with a negative SN between October 2006 and December 2017 at the Sahlgrenska University Hospital (Sweden) and Erasmus MC Cancer Institute (The Netherlands). According to the CP-GEP model, which can be applied to the primary melanoma tissue, the patients were stratified into high or low risk of recurrence. The primary aim was to assess the 5-year recurrence-free survival (RFS) of low- and high-risk CP-GEP. A secondary aim was to compare the CP-GEP model with the EORTC nomogram, a model based on clinicopathological variables only. Results: In total, 535 patients (stage I−II) were included. CP-GEP stratification among these patients resulted in a 5-year RFS of 92.9% (95% confidence interval (CI): 86.4−96.4) in CP-GEP low-risk patients (n = 122) versus 80.7% (95%CI: 76.3−84.3) in CP-GEP high-risk patients (n = 413; hazard ratio 2.93 (95%CI: 1.41−6.09), p < 0.004). According to the EORTC nomogram, 25% of the patients were classified as having a 'low risk' of recurrence (96.8% 5-year RFS (95%CI 91.6−98.8), n = 130), 49% as 'intermediate risk' (88.4% 5-year RFS (95%CI 83.6−91.8), n = 261), and 26% as 'high risk' (61.1% 5-year RFS (95%CI 51.9−69.1), n = 137). Conclusion: In these two independent European cohorts, the CP-GEP model was able to stratify patients with stage I−II melanoma into two groups differentiated by RFS.

Histopathological characteristics are instrumental to distinguish monomorphic from polymorphic maculopapular cutaneous mastocytosis in children.

BACKGROUND: Mastocytosis is characterized by the accumulation of mast cells (MCs) in the skin or other organs, and can manifest at any age. A significant number of paediatric mastocytosis cases persist after puberty. In particular, monomorphic maculopapular cutaneous mastocytosis (mMPCM) is often persistent and associated with systemic mastocytosis. However, clinical differentiation of MPCM from polymorphic (p)MPCM can be difficult. AIM: To identify histopathological features that can help to distinguish mMPCM from other subtypes of paediatric mastocytosis. METHODS: This was a retrospective study using skin biopsies from patients with any subtype of mastocytosis. The localization and density of the MC infiltrate, MC morphology and expression of aberrant markers were evaluated and correlated with clinical characteristics. RESULTS: In total, 33 biopsies were available for evaluation from 26 children [(10 with mMPCM, 5 with mastocytoma, 3 with diffuse cutaneous mastocytosis (DCM), 8 with pMPCM)] and 7 adults with MPCM. The MC number was increased in all patients, but was higher in children than adults (P < 0.01). The presence of mMPCM was associated with sparing of the papillary dermis from MC infiltration, whereas MC density in the papillary dermis was highest in pMPCM and DCM (P < 0.01). The positive predictive value of the presence of a reticular MC infiltrate for mMPCM was 72.7% (95% CI 51.4-87.0), and the negative predictive value was 83.3% (95% CI 42.2-97.2). There were no relevant differences in the expression of CD2, CD25 or CD30 between the different subtypes. CONCLUSION: Skin histopathology might enhance the phenotypical differentiation of mMPCM from other subtypes in children, thereby increasing the accuracy of one's prognosis.

Histopathological and immunological spectrum in response evaluation of talimogene laherparepvec treatment and correlation with durable response in patients with cutaneous melanoma.

Talimogene laherparepvec (T-VEC) is an intralesional oncolytic virotherapy for patients with irresectable stage III-IVM1a cutaneous melanoma. Although this treatment is considered to mainly act through T cell-mediated mechanisms, prominent numbers of plasma cells after T-VEC treatment have been described. The aim was to investigate how often these plasma cells were present, whether they were relevant in the response to treatment, and if these or other histopathological features were associated with durable response to treatment. Histopathological (granulomas, perineural inflammation, etc.) and immunological features [e.g. B cells/plasma cells (CD20/CD138) and T cells (CD3,CD4,CD8)] were scored and correlated with durable tumor response [i.e. complete response (CR) persisting beyond 6 months after treatment]. Plasmacellular infiltrate was examined with next-generation sequencing and immunohistochemistry (IgG, IgM, IgA, and IgD). Plasma cells were present in all T-VEC injected biopsies from 25 patients with melanoma taken at 3-5 months after starting treatment. In patients with a durable response ( n = 12), angiocentric features and granulomas were more frequently identified compared with patients without a (durable) response ( n = 13); 75% versus 29% for angiocentric features ( P = 0.015) and 58% versus 15% for granulomas ( P = 0.041). There was a class switch of IgM to IgG with skewing to certain dominant Ig heavy chain clonotypes. An angiocentric granulomatous pattern in T-VEC injected melanoma lesions was associated with a durable CR (>6 months). Plasma cells are probably a relevant feature in the mechanism of response but were not associated with durable response.

Prognostic Value of Stromal Tumor-Infiltrating Lymphocytes in Young, Node-Negative, Triple-Negative Breast Cancer Patients Who Did Not Receive (neo)Adjuvant Systemic Therapy.

PURPOSE: Triple-negative breast cancer (TNBC) is considered aggressive, and therefore, virtually all young patients with TNBC receive (neo)adjuvant chemotherapy. Increased stromal tumor-infiltrating lymphocytes (sTILs) have been associated with a favorable prognosis in TNBC. However, whether this association holds for patients who are node-negative (N0), young (< 40 years), and chemotherapy-naïve, and thus can be used for chemotherapy de-escalation strategies, is unknown. METHODS: We selected all patients with N0 TNBC diagnosed between 1989 and 2000 from a Dutch population-based registry. Patients were age < 40 years at diagnosis and had not received (neo)adjuvant systemic therapy, as was standard practice at the time. Formalin-fixed paraffin-embedded blocks were retrieved (PALGA: Dutch Pathology Registry), and a pathology review including sTILs was performed. Patients were categorized according to sTILs (< 30%, 30%-75%, and ≥ 75%). Multivariable Cox regression was performed for overall survival, with or without sTILs as a covariate. Cumulative incidence of distant metastasis or death was analyzed in a competing risk model, with second primary tumors as competing risk. RESULTS: sTILs were scored for 441 patients. High sTILs (≥ 75%; 21%) translated into an excellent prognosis with a 15-year cumulative incidence of a distant metastasis or death of only 2.1% (95% CI, 0 to 5.0), whereas low sTILs (< 30%; 52%) had an unfavorable prognosis with a 15-year cumulative incidence of a distant metastasis or death of 38.4% (32.1 to 44.6). In addition, every 10% increment of sTILs decreased the risk of death by 19% (adjusted hazard ratio: 0.81; 95% CI, 0.76 to 0.87), which are an independent predictor adding prognostic information to standard clinicopathologic variables (χ2 = 46.7, P < .001). CONCLUSION: Chemotherapy-naïve, young patients with N0 TNBC with high sTILs (≥ 75%) have an excellent long-term prognosis. Therefore, sTILs should be considered for prospective clinical trials investigating (neo)adjuvant chemotherapy de-escalation strategies.

Risk factors for metastatic cutaneous squamous cell carcinoma: Refinement and replication based on 2 nationwide nested case-control studies.

BACKGROUND: Risk factors for cutaneous squamous cell carcinoma (cSCC) metastasis have been investigated only in relatively small data sets. OBJECTIVE: To analyze and replicate risk factors for metastatic cSCC. METHODS: From English and Dutch nationwide cancer registry cohorts, metastatic cases were selected and 1:1 matched to controls. The variables were extracted from pathology reports from the National Disease Registration Service in England. In the Netherlands, histopathologic slides from the Dutch Pathology Registry were revised by a dermatopathologist. Model building was performed in the English data set using backward conditional logistic regression, whereas replication was performed using the Dutch data set. RESULTS: In addition to diameter and thickness, the following variables were significant risk factors for metastatic cSCC in the English data set (n = 1774): poor differentiation (odds ratio [OR], 4.56; 95% CI, 2.99-6.94), invasion in (OR, 1.69; 95% CI, 1.05-2.71)/beyond (OR, 4.43; 95% CI, 1.98-9.90) subcutaneous fat, male sex (OR, 2.59; 95% CI, 1.70-3.96), perineural/lymphovascular invasion (OR, 2.12; 95% CI, 1.21-3.71), and facial localization (OR, 1.57; 95% CI, 1.02-2.41). Diameter and thickness showed significant nonlinear relationships with metastasis. Similar ORs were observed in the Dutch data set (n = 434 cSCCs). LIMITATIONS: Retrospective use of pathology reports in the English data set. CONCLUSION: cSCC staging systems can be improved by including differentiation, clinical characteristics such as sex and tumor location, and nonlinear relationships for diameter and thickness.

Lectin and alternative complement pathway activation in cutaneous manifestations of IgA-vasculitis: A new target for therapy?

IgA-vasculitis is a systemic small-vessel leucocytoclastic vasculitis and is associated with a high morbidity. The disease can progress to IgA-vasculitis with nephritis (IgAVN) which can result in chronic renal failure. Complement activation is involved in the pathogenesis of IgA-vasculitis. A recent study has shown that cutaneous C3c deposition in IgA-vasculitis is associated with a higher risk to develop IgAVN. In the current study we investigated the different complement pathways that are activated in cutaneous IgA-vasculitis in order to reveal potential targets for intervention. In addition, we analyzed the association of complement factors with IgAVN and the clinical course of the disease. In this retrospective study, the clinicopathological features of 17 patients with IgA-vasculitis were compared with 25 non-IgA-vasculitis cases. Deposition of immunoglobulins and complement was analyzed by direct immunofluorescence for IgA, IgG, IgM, C1q, C4d, properdin, mannan-binding lectin (MBL), ficolin-2 (FCN2), MBL-associated serine protease 1/3 (MASP1/3), MASP2 and C3c. The vascular intensity and positive area was scored on a nominal scale and cumulative score was calculated by multiplying the intensity x area. Properdin was positive in 82% of IgA-vasculitis cases, reflecting alternative pathway activation. C4d was positive in 88% of IgA-vasculitis cases reflecting classical and/or lectin pathway activation, although only 12% of cases were positive for C1q. Lectin pathway activation was demonstrated by deposition of MBL (47%), MASP1/3 (53%) and MASP2 (6%) while FCN2 was found negative. Significantly more deposition of MASP1/3 was found in IgA-vasculitis versus non-IgA-vasculitis. This study demonstrates for the first time activation of lectin and alternative pathways in cutaneous manifestations of IgA-vasculitis. Hence, drugs that intervene in these complement pathways may be an interesting more targeted alternative to the current drugs, in reducing local cutaneous symptoms of the disease, with potentially less side-effects. No association was found between complement activation and IgAVN and/or response to therapy. Therefore, it is unlikely that intervention in complement activation will lead to a better clinical course of the disease.

Cumulative incidence and disease-specific survival of metastatic cutaneous squamous cell carcinoma: A nationwide cancer registry study.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) represents the most serious form of keratinocyte cancers because of its metastatic potential. Studies on nationwide incidence and disease-specific survival rates of metastatic cSCC (mcSCC) are lacking. OBJECTIVE: To investigate the cumulative incidence and disease-specific survival of patients with mcSCC in the Dutch population and assess patient-based risk factors. METHODS: We conducted a nationwide cancer registry study including all patients with the first cSCC in 2007 or 2008, using data from the Netherlands Cancer Registry, the nationwide network and registry of histopathology and cytopathology, and Statistics Netherlands. Cumulative incidence and Kaplan-Meier curves were calculated, and time-dependent Cox proportional hazards regression analyses were used. RESULTS: Of the 11,137 patients, metastases developed in 1.9% (n = 217). The median time to metastasis was 1.5 years (interquartile range 0.6-3.8 years). The risk factors were age (adjusted hazard ratio [aHR] 1.03, 95% CI 1.02-1.05), male sex (aHR 1.7, 95% CI 1.3-2.3), and immunosuppression (aHR [organ transplant recipient] 5.0, 95% CI 2.5-10.0; aHR [hematologic malignancy] 2.7, 95% CI 1.6-4.6). The 5-year disease-specific survival for patients with mcSCC was 79.1%. LIMITATIONS: Only histopathologically confirmed mcSCCs were included. CONCLUSION: About 2% of cSCCs metastasize, with higher risk for men, increasing age, and immunocompromised patients. Disease-specific survival for patients with mcSCC is high.

Validation of four cutaneous squamous cell carcinoma staging systems using nationwide data.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is the second most common cancer worldwide with relatively low metastatic potential (2-5%). Developments in therapeutic options have highlighted the need to better identify high-risk patients who could benefit from closer surveillance, adjuvant therapies and baseline/follow-up imaging, while at the same time safely omitting low-risk patients from further follow-up. Controversy remains regarding the predictive performance of current cSCC staging systems and which methodology to adopt. OBJECTIVES: To validate the performance of four cSCC staging systems [American Joint Committee on Cancer 8th edition (AJCC8), Brigham and Women's Hospital (BWH), Tübingen and Salamanca T3 refinement] in predicting metastasis using a nationwide cohort. METHODS: A nested case-control study using data from the National Disease Registration Service, England, 2013-2015 was conducted. Metastatic cSCC cases were identified using an algorithm to identify all potential cases for manual review. These were 1 : 1 matched on follow-up time to nonmetastatic controls randomly selected from 2013. Staging systems were analysed for distinctiveness, homogeneity, monotonicity, specificity, positive predictive value (PPV), negative predictive value (NPV) and c-index. RESULTS: We included 887 metastatic cSCC cases and 887 nonmetastatic cSCC controls. The BWH system showed the highest specificity [92.8%, 95% confidence interval (CI) 90.8-94.3%, PPV (13.2%, 95% CI 10.6-16.2) and c-index (0.84, 95% CI 0.82-0.86). The AJCC8 showed superior NPV (99.2%, 95% CI 99.2-99.3), homogeneity and monotonicity compared with the BWH and Tübingen diameter and thickness classifications (P < 0.001). Salamanca refinement did not show any improvement in AJCC8 T3 cSCC staging. CONCLUSIONS: We validated four cSCC staging systems using the largest nationwide dataset of metastatic cSCC so far. Although the BWH system showed the highest overall discriminative ability, PPV was low for all staging systems, which shows the need for further improvement and refining of current cSCC staging systems.

Assessment of the Diagnostic Accuracy of Baseline Clinical Examination and Ultrasonographic Imaging for the Detection of Lymph Node Metastasis in Patients With High-risk Cutaneous Squamous Cell Carcinoma of the Head and Neck.

IMPORTANCE: Patients with cutaneous squamous cell carcinoma (SCC) of the head and neck may develop lymph node metastasis; therefore, additional workup of the regional lymph nodes in these patients should be considered. However, there is uncertainty regarding the value of baseline ultrasonographic imaging in addition to clinical examination for the detection of metastasis. OBJECTIVE: To assess the diagnostic accuracy of clinical examination and baseline ultrasonography for the detection of metastasis among patients with high-risk cutaneous SCC of the head and neck and to assess the accuracy of ultrasonography when baseline clinical examination produces negative results. DESIGN, SETTING, AND PARTICIPANTS: This diagnostic study was conducted among a retrospective cohort of 233 patients with 246 high-risk cutaneous SCC tumors of the head and neck. The study included all patients with high-risk cutaneous SCC of the head and neck who received clinical examination and baseline ultrasonographic imaging of their lymph nodes at the Erasmus Medical Center Cancer Institute, a tertiary referral hospital for patients with skin cancer in Rotterdam, the Netherlands, between January 1, 2015, and December 31, 2017. Data were analyzed from October 13, 2020, to September 29, 2021. MAIN OUTCOMES AND MEASURES: Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Fine-needle aspiration cytologic biopsy and 6 months of follow-up per patient were used as the reference standards. RESULTS: Among 233 patients (176 men [75.5%]; median age, 79.1 years [IQR, 71.5-83.7 years]; data on race and ethnicity were not collected) with 246 high-risk cutaneous SCC tumors of the head and neck, 20 metastases were cytologically confirmed at baseline, and 2 metastases were detected during 6 months of follow-up, yielding a 9% metastasis rate. The sensitivity of clinical examination was 50% (95% CI, 28%-72%), and the specificity was 96% (95% CI, 93%-98%). The PPV and NPV were 55% (95% CI, 36%-72%) and 95% (95% CI, 93%-97%), respectively. In the total cohort, ultrasonography had a sensitivity of 91% (95% CI, 71%-99%) and a specificity of 78% (95% CI, 72%-83%), with a PPV of 29% (95% CI, 23%-35%) and an NPV of 99% (95% CI, 96%-100%). In the group of patients with negative results at baseline clinical examination, 9 of 11 metastases were detected by ultrasonography, with 82% sensitivity (95% CI, 48%-98%); specificity was 79% (95% CI, 73%-84%), PPV was 17% (95% CI, 12%-23%), and NPV was 99% (95% CI, 96%-100%). CONCLUSIONS AND RELEVANCE: In this diagnostic study, among a cohort of patients with high-risk cutaneous SCC of the head and neck, baseline ultrasonography was more sensitive than clinical examination alone for the detection of lymph node metastasis. In the setting of a negative result at baseline clinical examination, ultrasonography had high sensitivity for detecting nodal metastases, but this sensitivity should be evaluated against the high rate of false-positive findings.

False positive FDG uptake in melanoma patients treated with talimogene laherparepvec (T-VEC).

Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex virus-1-based oncolytic immunotherapy and has been approved for the local treatment of unresectable (stage IIIB/C and IVM1a) cutaneous melanoma. During T-VEC treatment, tumor response is often evaluated using [18F]2-fluoro-2-deoxy- d-glucose(FDG) positron emission tomography/computed tomography (PET/CT). In a Dutch cohort (n = 173), almost one-third of patients developed new-onset FDG uptake in uninjected locoregional lymph nodes during T-VEC. In 36 out of 53 (68%) patients with new nodal FDG uptake, nuclear medicine physicians classified this FDG uptake as "suspected metastases" without clinical or pathological confirmation in the majority of patients. These false positive results indicate that new-onset FDG uptake in locoregional lymph nodes during T-VEC treatment does not necessarily reflect progressive disease, but may be associated with immune infiltration. In current clinical practice, physicians should be aware of the high false positive rate of FDG uptake during treatment with T-VEC in patients with melanoma. Therefore, pathological examination of lymph node lesions with new FDG uptake is recommended to differentiate between progressive disease and immune infiltration after treatment with T-VEC.

Molecular testing in metastatic basal cell carcinoma.

BACKGROUND: Metastatic basal cell carcinoma (mBCC) is a very rare entity, and diagnosis can be challenging. Therapeutic options are limited, and response to targeted therapy is poor. OBJECTIVE: To demonstrate a clonal relationship between BCCs and their metastases and to explore which hedgehog pathway-related mutations are involved in mBCC. METHODS: Genetic analysis was conducted in 10 primary BCCs and their metastases. Genes relevant for BCC development were analyzed in tumor and metastasis material with small molecule molecular inversion probes (smMIPs) for PTCH1, PTCH2, SMO, SUFU, GLI2, and TP53 or with targeted next generation sequencing of the same genes and CDKN2A, CDKN2B, CIC, DAXX, DDX3X, FUBP1, NF1, NF2, PTEN, SETD2, TRAF7, and the TERT promoter. RESULTS: In 8 of 10 patients, identical gene mutations could be demonstrated in the primary tumors and their metastases. A broad spectrum of mutations was found. Four patients had SMO mutations in their tumor or metastasis, or both. All SMO mutations found were known to cause resistance to targeted therapy with vismodegib. LIMITATIONS: In 2 patients there was insufficient qualitative DNA available for genetic analysis. CONCLUSIONS: Molecular testing can help to identify the origin of a BCC metastasis and may be of prognostic and therapeutic value.

Trichoblastic carcinosarcoma with panfollicular differentiation (panfollicular carcinosarcoma) and CTNNB1 (beta-catenin) mutation.

We present a case of trichoblastic carcinosarcoma with panfollicular differentiation. An 80-year-old man presented with a lesion on the left ear, which had been present for several months. Histopathology revealed a well-demarcated neoplasm in the dermis composed of intimately intermingled malignant epithelial and mesenchymal cells. The epithelial component showed multilineage follicular differentiation toward all of the elements of a normal hair follicle. Molecular analysis revealed identical molecular aberrations in both epithelial and mesenchymal components including CTNNB1 and SUFU mutations. To the best of our knowledge, this is the first report of panfollicular carcinosarcoma and of the presence of a CTNNB1 mutation in trichoblastic carcinosarcoma.