Factors associated with residual tumor at time of Mohs micrographic surgery for basal cell and squamous cell carcinomas.

BACKGROUND: Residual tumor is not always clinically apparent following biopsy of cutaneous carcinomas, which may prompt patients to question the need for definitive treatment. OBJECTIVE: We investigated the percentage of cases in which residual tumor was histologically present at the time of Mohs micrographic surgery (MMS) for basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) and investigated factors associated with residual tumor. METHODS: We examined 483 MMS cases performed for biopsy-proven BCC (n = 287) and SCC (n = 196) between October 2022 and April 2023. Single-stage MMS specimens were step-sectioned en face to exhaust the block. Univariate and multivariable logistic regression models were created. RESULTS: Residual tumor was identified in 83.3% of BCC and 66.8% of SCC at the time of MMS (P = .01). In patients clinically appearing tumor-free following biopsy, residual histologic tumor was identified in 68.2% of BCC and 41.5% of SCC. Residual tumor was significantly more likely in men (P = .04), high-risk sites (P = .002), smaller biopsy sizes (P = .0003), and larger preoperative sizes (P < .0001). LIMITATIONS: Single center, retrospective cohort. CONCLUSION: The majority of patients with BCC and SCC have residual histologic tumor at the time of MMS, oftentimes even when tumor is not clinically apparent. Multiple factors impact the presence/absence of residual tumor.

Identifying critical quality metrics in Mohs Surgery: A national expert consensus process.

BACKGROUND: Amid a movement toward value-based healthcare, increasing emphasis has been placed on outcomes and cost of medical services. To define and demonstrate the quality of services provided by Mohs surgeons, it is important to identify and understand the key aspects of Mohs micrographic surgery (MMS) that contribute to excellence in patient care. OBJECTIVE: The purpose of this study is to develop and identify a comprehensive list of metrics in an initial effort to define excellence in MMS. METHODS: Mohs surgeons participated in a modified Delphi process to reach a consensus on a list of metrics. Patients were administered surveys to gather patient perspectives. RESULTS: Twenty-four of the original 66 metrics met final inclusion criteria. Broad support for the initiative was obtained through physician feedback. LIMITATIONS: Limitations of this study include attrition bias across survey rounds and participation at the consensus meeting. Furthermore, the list of metrics is based on expert consensus instead of quality evidence-based outcomes. CONCLUSION: With the goal of identifying metrics that demonstrate excellence in performance of MMS, this initial effort has shown that Mohs surgeons and patients have unique perspectives and can be engaged in a data-driven approach to help define excellence in the field of MMS.

Frequencies of house fly proto-Y chromosomes across populations are predicted by temperature heterogeneity within populations.

Sex chromosomes often differ between closely related species and can even be polymorphic within populations. Species with multifactorial sex determination segregate for multiple different sex determining loci within populations, making them uniquely informative of the selection pressures that drive the evolution of sex chromosomes. The house fly (Musca domestica) is a model species for studying multifactorial sex determination because male determining genes have been identified on all six of the chromosomes, which means that any chromosome can be a "proto-Y". Natural populations of house fly also segregate for a recently derived female-determining locus, meaning house flies also have a proto-W chromosome. The different proto-Y chromosomes are distributed along latitudinal clines on multiple continents, their distributions can be explained by seasonality in temperature, and they have temperature-dependent effects on physiological and behavioral traits. It is not clear, however, how the clinal distributions interact with the effect of seasonality on the frequencies of house fly proto-Y and proto-W chromosomes across populations. To address this question, we measured the frequencies of house fly proto-Y and proto-W chromosomes across nine populations in the United States of America. We confirmed the clinal distribution along the eastern coast of North America, but it is limited to the eastern coast. In contrast, annual mean daily temperature range predicts proto-Y chromosome frequencies across the entire continent. Our results therefore suggest that temperature heterogeneity can explain the distributions of house fly proto-Y chromosomes in a way that does not depend on the cline.

Predictor Variables Associated With Dermatology Referral Completion and the Impact on Surgical Treatment: A Retrospective Cohort Study.

BACKGROUND: Delays or failure to complete a dermatologic referral may affect health care outcomes. Factors associated with these delays remain understudied. OBJECTIVE: This study investigated socioeconomic and demographic factors associated with delays or failure to complete dermatology referrals and potential impact on surgical outcomes. METHODS: A retrospective chart review was performed for 400 patients internally referred to an academic dermatology center from 19 primary-care clinics from July 2018 to June 2019. Only patients referred after an in-person primary-care visit in which the provider documented a specific concerning lesion were included. Multivariate analyses were performed to explore variables associated with delays or failure to complete dermatology referrals. RESULTS: Patients were more likely to complete their referral if they had a personal history (adjusted odds ratio [aOR] = 7.843, 95% CI 1.383-14.304) or family history (aOR = 11.307, 95% CI 2.344-20.27) of skin cancer. Patients were more likely to delay referral completion past 30 days if they were ages 18 to 34 (aOR = 6.665, 95% CI 1.285-12.044) and less likely to delay referral past 30 days if they had a previous history of skin cancer (aOR = 0.531, 95% CI 0.181-0.882). LIMITATIONS: Single institution, retrospective study, limited surgical patients. CONCLUSION: Understanding factors associated with delays in dermatology referral completion can help identify at-risk patient populations.

Genetics, genomics and mechanisms responsible for high levels of pyrethroid resistance in Musca domestica.

Insecticide resistance is both economically important and evolutionarily interesting phenomenon. Identification of the mutations responsible for resistance allows for highly sensitive resistance monitoring and allows tools to study the forces (population genetics, fitness costs, etc.) that shape the evolution of resistance. Genes coding for insecticide targets have many well-characterized mutations, but the mutations responsible for enhanced detoxification have proven difficult to identify. We employed multiple strategies to identify the mutations responsible for the extraordinarily high permethrin resistance in the KS17-R strain of house fly (Musca domestica): insecticide synergist assays, linkage analysis, bulk segregant analyses (BSA), transcriptomics and long read DNA (Nanopore) sequencing. The >85,100-fold resistance in KS17-R was partially suppressed by the insecticide synergists piperonyl butoxide and S,S,S-tributylphosphorothionate, but not by diethyl maleate nor by injection. This suggests the involvement of target site insensitivity, CYP-mediated resistance, possibly hydrolase mediated resistance and potentially other unknown factors. Linkage analysis identified chromosomes 1, 2, 3 and 5 as having a role in resistance. BSA mapped resistance loci on chromosomes 3 and 5. The locus on chromosome 3 was centered on the voltage sensitive sodium channel. The locus on chromosome 5 was associated with a duplication of multiple detoxification genes. Transcriptomic analyses and long read DNA sequencing revealed overexpressed CYPs and esterases and identified a complex set of structural variants at the chromosome 5 locus.

Piperonyl butoxide elicits a robust transcriptional response in adult Drosophila melanogaster.

While much attention has been devoted to understanding the transcriptional changes underlying resistance to insecticides, comparatively little is known about the transcriptional response of naive insects to agrochemicals. In this study, we analyze the transcriptomic response of an insecticide susceptible strain of Drosophila melanogaster to nine agrochemicals using a robust method that goes beyond classical replication standards. Our findings demonstrate that exposure to piperonyl butoxide (PBO), but not to eight other compounds, elicits a robust transcriptional response in a wild-type strain of Drosophila melanogaster. PBO exposure leads to the upregulation of a subset of Cyps, GSTs, UGTs and EcKls. This response is both time and concentration-dependent, suggesting that the degree of inhibition of P450 activity correlates with the magnitude of the transcriptional response. Furthermore, the upregulation of these enzymes is excluded from reproductive organs. Additionally, different sets of genes are regulated in the digestive/secretory tract and the carcass. Our results suggest that P450s play a role in metabolizing yet unidentified endogenous compounds and are involved in an as-yet-unknown physiological regulatory feedback loop.

Isolation and characterization of the decreased cuticular penetration mechanism of fluralaner resistance in the house fly, Musca domestica.

Decreased cuticular penetration has been documented as a mechanism of resistance in several insects, yet this mechanism remains poorly understood. Levels of resistance conferred, effects of the physicochemical properties on the manifestation of resistance and the effects of different routes of exposure are largely unknown. We recently selected a strain (FlurR) of house fly that was >11,000-fold resistance to fluralaner, and decreased cuticular penetration was one of the mechanisms of resistance (Norris et al., 2023). We sought to isolate the decreased penetration mechanism from FlurR into the background of the susceptible aabys strain, and to characterize the protection it conferred to fluralaner and other insecticides. We successfully isolated the decreased penetration mechanism and found that it conferred 7.1-fold resistance to fluralaner, and 1.4- to 4.9-fold cross-resistance to five other insecticides by topical application. Neither mass, metabolic lability, vapor pressure, nor logP explained the differences in the resistance ratios. The mechanism also conferred cross resistance by residual and feeding exposure, although at reduced levels compared to topical application. Remaining data gaps in our understanding of this mechanism are discussed.

Predictors of patient satisfaction with Mohs micrographic surgery at time of surgery and 3 months postsurgery: A prospective cohort study.

BACKGROUND: Despite the importance of patient satisfaction in ensuring high-quality care, studies investigating patient satisfaction in Mohs micrographic surgery (MMS) are limited. OBJECTIVE: We investigated the factors associated with patient satisfaction in MMS for nonmelanoma skin cancer and how patient satisfaction changes in the postoperative period. METHODS: In this prospective cohort study including 100 patients, patient satisfaction surveys were administered at the time of surgery and at 3 months postsurgery. Sociodemographic characteristics, medical history, and surgical parameters were collected by chart review. Univariate linear and logistic regression models were created to examine these relationships. RESULTS: Decreased satisfaction was observed in patients requiring 3 or more MMS stages both at the time of surgery (P = .047) and at 3 months post-surgery (P = .0244). Patients with morning procedures ending after 1:00 pm had decreased satisfaction at the time of surgery (P = .019). A decrease in patient satisfaction between the time of surgery and 3 months postsurgery was observed in patients with surgical sites on the extremities (P = .036), larger preoperative lesion sizes (P = .012), and larger defect sizes (P = .033). LIMITATIONS: Single-institution data, self-selection bias, and recall bias. CONCLUSION: Patient satisfaction with MMS is impacted by numerous factors and remains dynamic over time.

New insights into immune genes and other expanded gene families of the house fly, Musca domestica, from an improved whole genome sequence.

The house fly, Musca domestica, is a pest of livestock, transmits pathogens of human diseases, and is a model organism in multiple biological research areas. The first house fly genome assembly was published in 2014 and has been of tremendous use to the community of house fly biologists, but that genome is discontiguous and incomplete by contemporary standards. To improve the house fly reference genome, we sequenced, assembled, and annotated the house fly genome using improved techniques and technologies that were not available at the time of the original genome sequencing project. The new genome assembly is substantially more contiguous and complete than the previous genome. The new genome assembly has a scaffold N50 of 12.46 Mb, which is a 50-fold improvement over the previous assembly. In addition, the new genome assembly is within 1% of the estimated genome size based on flow cytometry, whereas the previous assembly was missing nearly one-third of the predicted genome sequence. The improved genome assembly has much more contiguous scaffolds containing large gene families. To provide an example of the benefit of the new genome, we used it to investigate tandemly arrayed immune gene families. The new contiguous assembly of these loci provides a clearer picture of the regulation of the expression of immune genes, and it leads to new insights into the selection pressures that shape their evolution.

Patient Anxiety Related to Patient-Perceived Delays in Surgical Treatment of Skin Cancer.

BACKGROUND: Patients undergoing dermatologic surgery report higher anxiety levels than those undergoing nonsurgical treatments. However, little is known about the association between patient-perceived delays in skin cancer surgery and patient-reported anxiety. OBJECTIVE: To examine the relationship between patient-perceived delays in surgery and patient-reported anxiety. METHODS MATERIALS: Patients undergoing wide local excision or Mohs micrographic surgery were recruited to complete a survey to assess perception of surgical delay and anxiety related to skin cancer surgery using the validated Psychosocial Screen for Cancer-Revised. Demographic and surgical characteristics were collected through chart review. Chi-square and Student t -tests were used to compare demographic and surgical information between patients who did and did not perceive a surgical delay. Differences in anxiety and depression scores for patients who did and did not report a delay were assessed using univariate and multivariate regressions. RESULTS: Twenty-seven percent ( N = 33) of patients perceived a surgical delay. Perception of surgical delay was associated with increased time between biopsy and surgery ( p = .0001) and increased self-reported anxiety scores after controlling for various demographic and surgical factors ( p = .038). CONCLUSION: Patient-perceived delays in dermatologic surgery are associated with increased time to surgery and patient-reported anxiety.

Mechanisms of Acute Right Ventricular Injury in Cardiothoracic Surgical and Critical Care Settings: Part 2.

The right ventricle (RV) is intricately linked in the clinical presentation of critical illness; however, the basis of this is not well-understood and has not been studied as extensively as the left ventricle. There has been an increased awareness of the need to understand how the RV is affected in different critical illness states. In addition, the increased use of point-of-care echocardiography in the critical care setting has allowed for earlier identification and monitoring of the RV in a patient who is critically ill. The first part of this review describes and characterizes the RV in different perioperative states. This second part of the review discusses and analyzes the complex pathophysiologic relationships between the RV and different critical care states. There is a lack of a universal RV injury definition because it represents a range of abnormal RV biomechanics and phenotypes. The term "RV injury" (RVI) has been used to describe a spectrum of presentations, which includes diastolic dysfunction (early injury), when the RV retains the ability to compensate, to RV failure (late or advanced injury). Understanding the mechanisms leading to functional 'uncoupling' between the RV and the pulmonary circulation may enable perioperative physicians, intensivists, and researchers to identify clinical phenotypes of RVI. This, consequently, may provide the opportunity to test RV-centric hypotheses and potentially individualize therapies.

Selection and characterization of spinetoram resistance in field collected Drosophila melanogaster.

Insecticides are commonly employed in vineyards to control vinegar flies and limit sour rot disease. Widespread resistance to available insecticides is having a negative impact on managing Drosophila melanogaster populations, rendering control of sour rot more difficult. An insecticide registered for use in vineyards to which resistance is not yet widespread (at least in New York and Missouri) is spinetoram. Spinetoram targets the nicotinic acetylcholine receptor α6, and mutations in α6 have been associated with resistance in some insects. Our goals were to select for a spinetoram resistant strain of D. melanogaster (starting with field collected populations), characterize the resistance, and identify the mutation responsible. After five selections a strain (SpinR) with >190-fold resistance was obtained. Resistance could not be overcome by insecticide synergists, suggesting an altered target site was involved. We cloned and sequenced the α6 allele from the spinetoram resistant strain and identified a mutation causing a glycine to alanine change at amino acid 301 (equivalent position to the G275E mutation found in some spinosad/spinetoram resistant insects). This mutation was found at low levels in field populations, but increased with each selection until it became homozygous in SpinR. We discuss how the identification of the spinetoram resistance mutation can be used for resistance management.

Frequencies and distribution of kdr and Ace alleles that cause insecticide resistance in house flies in the United States.

House flies (Musca domestica L) are nuisances and vectors of pathogens between and among humans and livestock. Population suppression has been accomplished for decades with pyrethroids and acetylcholinesterase (AChE) inhibitors, but recurrent selection has led to increased frequency of alleles conferring resistance to those two classes of active ingredients (Geden et al., 2021). A common mechanism of resistance to both classes involves an altered target site (mutations in Voltage gated sodium channel (Vgsc) for pyrethroids or in Ace for AChE inhibitors). As part of ongoing efforts to understand the origin, spread and evolution of insecticide resistance alleles in house fly populations, we sampled flies in 11 different US states, sequenced, and then estimated frequencies of the Vgsc and Ace alleles. There was substantial variation in frequencies of the four common knockdown resistance alleles (kdr (L1014F), kdr-his (L1014H), super-kdr (M918T + L10414F) and 1B (T929I + L1014F) across the sampled states. The kdr allele was found in all 11 states and was the most common allele in four of them. The super-kdr allele was detected in only six collections, with the highest frequencies found in the north, northeast and central United States. The kdr-his allele was the most common allele in PA, NC, TN and TX. In addition, a novel super-kdr-like mutation in mutually exclusive exon 17a was found. The overall frequencies of the different Ace alleles, which we name based on the amino acid present at the mutation sites (V260L, A316S, G342A/V and F407Y), varied considerably between states. Five Ace alleles were identified: VAGF, VAVY, VAGY, VAAY and VSAY. Generally, the VSAY allele was the most common in the populations sampled. The susceptible allele (VAGF) was found in all populations, ranging in frequency from 3% (KS) to 41% (GA). Comparisons of these resistance allele frequencies with those previously found suggests a dynamic interaction between the different alleles, in terms of levels of resistance they confer and likely fitness costs they impose in the absence of insecticides.

Selection for, and characterization of, fluralaner resistance in the house fly, Musca domestica.

House flies, Musca domestica (L), are the mechanical vector of >100 human and animal pathogens, including those that are antibiotic-resistant. Given that house flies are associated closely with human and livestock activity, they present medical and veterinary health concerns. Although there are numerous strategies for control of house fly populations, chemical control has been favored in many facilities. Products with pyrethroid active ingredients have been used predominantly for >35 years in space sprays. As a result, strong selection for pyrethroid resistance has led to reduced control of many populations. Reliance on a limited number of insecticides for decades has created fly control problems necessitating the discovery and formulation of new control chemistries. Fluralaner is a relatively new insecticide and acaricide (first reported in 2010), belonging to the isoxazoline class. These insecticides target the glutamate- and gamma-aminobutyric acid-gated (GABA) chloride channels, which is a different mode of action from other insecticides used against house flies. Although is it not currently registered for house fly control in the United States, previous work has shown that fluralaner is highly toxic to house flies and that there was limited cross-resistance found in laboratory strains having high levels of resistance to other insecticides. Herein, we characterized the time and age dependency of fluralaner toxicity, detected cross-resistance in populations from across the United States, and selected a highly resistant (>11,000-fold) house fly strain. We found that the fluralaner LD50 of 18-24 h old flies was 2-fold higher than for 5-6 d old flies. This appears to be due to more rapid penetration of fluralaner into the 5-6 d old flies. Fluralaner resistance was inherited as an intermediate to incompletely dominant trait and was mapped to chromosomes 5 and 3. Resistance could be suppressed to 7-fold with piperonyl butoxide, suggesting that cytochrome P450 (CYP)-mediated detoxification was a major mechanism of resistance. Decreased penetration was also demonstrated as a mechanism of resistance. The utility of fluralaner for house fly control is discussed.

Surgical Techniques Following Free Cartilage Grafting.

BACKGROUND: Reconstruction of surgical defects with free cartilage grafts poses unique challenges. OBJECTIVES: To characterize surgical techniques following free cartilage grafting. MATERIALS AND METHODS: A literature review was performed using the Embase, PubMed Medline, Cochrane Library, ClinicalTrials.gov , and Web of Science databases from inception to May 21, 2021. Studies describing free cartilage grafts harvested from the ear or nose under local anesthesia, specifically for reconstruction of facial surgical defects, were selected for inclusion. Only surgical defects resulting from tumor resection were included. RESULTS: In total, 34 studies involving 713 patients with 723 surgical defects met inclusion criteria. The mean age of patients was 63.3 ± 10.4 years. Free cartilage grafts were most commonly harvested from the ear (93.1%). The most common recipient site was the nose (90.3%), followed by the lower eyelid (6.7%) and ear (3.0%). CONCLUSION: Free cartilage grafts are an effective reconstructive option for patients with deep or cartilaginous defects that have compromised structural support on the nose, ear, or eyelid.

A Multimetric Readability Analysis of Online Patient Educational Materials for Submental Fat Reduction.

BACKGROUND: Patients often utilize the Internet to seek information related to their care. This study assesses the readability of online patient educational materials for submental fat reduction. METHODS: Patient educational materials from the 12 most popular websites related to submental fat reduction were downloaded and assessed for readability grade level using 10 unique scales. RESULTS: Analysis of the 12 most popular websites (and corresponding 47 articles) revealed that patient educational materials were written, on average, at an 11th grade reading level. The Flesch Reading Ease score was 48.9 (range 39.8-59.2), representing a "difficult" level of reading. Mean readability grade levels (range 9-13th grade for individual websites) were as follows: Coleman-Liau, 11.1; Flesch-Kincaid, 10.8; FORCAST, 10.8; Fry Graph, 10.1; Gunning Fog, 12.7; New Dale-Chall, 10.1; New Fog Count, 11.8; Simple Measure of Gobbledygook, 11.7; Raygor, 6.7. No website was at the 6th grade reading level for patient educational materials recommended by the American Medical Association and National Institutes of Health. CONCLUSIONS: Online patient educational materials for submental fat reduction are written well above the recommended reading level. Recognition of disparities in health literacy is necessary to enable patients to make informed decisions and become active participants in their own care. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266.

NCCN Guidelines® Insights: Squamous Cell Skin Cancer, Version 1.2022.

The NCCN Guidelines for Squamous Cell Skin Cancer provide recommendations for diagnostic workup, clinical stage, and treatment options for patients with cutaneous squamous cell carcinoma. The NCCN panel meets annually to discuss updates to the guidelines based on comments from panel members and the Institutional Review, as well as submissions from within NCCN and external organizations. These NCCN Guidelines Insights focus on the introduction of a new surgical recommendation terminology (peripheral and deep en face margin assessment), as well as recent updates on topical prophylaxis, immunotherapy for regional and metastatic disease, and radiation therapy.

Tumor primary site as a prognostic factor for Merkel cell carcinoma disease-specific death.

BACKGROUND: Merkel cell carcinoma (MCC) primary site has not been fully investigated as a potential prognostic factor. OBJECTIVE: To determine the incidence by tumor primary site of death due to MCC. METHODS: We undertook a retrospective analysis of the Survival, Epidemiology, and End Results database. MCC patients treated between 1973 and 2016 were grouped by tumor primary site and a competing risks analysis was performed to test the impact of primary site on disease-specific death. Cumulative incidence of Merkel cell carcinoma-specific mortality (CMMI) at 5 years was estimated for each primary site. RESULTS: Of 9407 MCC patients identified, 6305 (67.0%) had localized disease, 2397 (25.5%) had regional metastasis, and 705 (7.5%) had distant metastasis. Tumor primary site was predictive of CMMI and varied by stage at diagnosis. Tumors involving the scalp/neck carried the highest CMMI among localized MCC (26.0%). Tumors involving the lip had the highest CMMI among MCC with regional metastasis (56.7%) and distant metastasis (82.1%). LIMITATIONS: Tumor size data were missing for a large proportion of patients, precluding stratification by stage according to current American Joint Committee on Cancer guidelines. CONCLUSIONS: Probability of MCC disease-specific death varies by primary site. The primary site of the tumor may be useful as a prognostic indicator for MCC.

Parallel veno-venous and veno-arterial extracorporeal membrane circuits for coexisting refractory hypoxemia and cardiovascular failure: a case report.

BACKGROUND: The complexity of extracorporeal membrane oxygenation (ECMO) techniques continues to evolve. Different cannulation methods and configurations have been proposed as a response to a challenging cardiovascular and pulmonary physiology of the patients. The use of parallel ECMO circuits represents a unique and novel approach for patients with refractory respiratory failure and cardiovascular collapse with very large body surface areas. CASE PRESENTATION: We present the case of a 25-year-old morbidly obese male patient admitted for severe acute respiratory distress syndrome (ARDS) and refractory hypoxemia, requiring institution of double cannulation for veno-venous ECMO. Since his hypoxemia persisted, likely due to insufficient flows given his large body surface area, an additional drainage venous cannula was implemented to provide higher flows, temporarily addressing his oxygenation status. Unfortunately, the patient developed concomitant cardiogenic shock refractory to inotropic support and extracorporeal fluid removal, further worsening his oxygenation status, thus the decision was to institute four-cannulation/parallel-circuits veno-venous and veno-arterial ECMO, successfully controlling both refractory hypoxemia and cardiogenic shock. CONCLUSIONS: Our case illustrates a novel and complex approach for combined severe ARDS and cardiovascular collapse through the use of parallel veno-venous and veno-arterial ECMO circuits, and exemplifies the expansion of ECMO techniques and its life-saving capabilities when conservative approaches are futile.

Pure and Mixed Desmoplastic Melanomas: A Retrospective Clinicopathologic Comparison of 33 Cases.

BACKGROUND: Pure and mixed desmoplastic melanomas (DMs) may have different natural histories and behaviors. METHODS: We conducted a retrospective review of patients diagnosed with DM at our institution between January 1997 and April 2019. A total of 33 unique DMs were identified and subsequently analyzed based on the histologic type (pure vs. mixed). RESULTS: The majority (57.6%) of our cases were classified as pure histology. Patients with pure DMs were more likely to be men (P = 0.035) and be older than 65 years (P = 0.019) compared with patients with mixed DMs. Patients with mixed DM were more likely to have mitoses present (P = 0.001) compared with patients with pure DM. There were no differences in ulceration, perineural invasion, vascular invasion, or survival between patients with pure and mixed histologic subtypes. In addition, no differences in sentinel lymph node biopsy, radiation, or chemotherapy were noted between the 2 histologic subtypes. Immunohistochemistry showed that 27.3% of the pure DMs stained with Melan-A and HMB45 were positive for these immunomarkers. CONCLUSIONS: Pure and mixed variants of DM were found to have similar clinicopathologic characteristics. Patients with the mixed histologic subtype were more likely to have mitoses, but no difference in the therapeutic management or patient survival was seen between the 2 subtypes.