A clinical review and history of pubic lice.

The ectoparasite Pthirus pubis (PtP), commonly known as the crab or pubic louse, has plagued primates from prehistoric apes to Homo sapiens. We combed the literature from antiquity to the present day, reviewing the pubic louse's origins, its evolution with mankind, and its presentation and management. MEDLINE and EMBASE provided the greatest yield of literature compared with other databases. Estimates for PtP incidence range from 0.3% to 4.6% and for prevalence around 2% in adults. War, disasters and overcrowding support lice transmission, but modern pubic hair grooming has reduced the incidence of PtP in recent years. PtP, is usually found on pubic hair, but may infest scalp and body hair, eyebrows and eyelashes. Reports suggest the possibility of PtP as a vector for Bartonella spp. and Acinetobacter spp., which require further study. Transmission of PtP is via close contact, so sexual abuse and concomitant sexually transmitted infections should be considered. Symptoms and signs of infestation include pruritus, red papules and rust/brown deposits from feeding or faecal matter. Visualization of live lice confirms the diagnosis. Traditional treatments include hand-picking and combing, but in modern times pediculicidal products may generate faster resolution. Permethrin or pyrethrins are the first-line recommendations. Resistance to pediculicides is common with head lice and is presumed likely with PtP, although data are lacking. Pseudoresistance occurs as a result of poor compliance, incorrect or ineffective dosing, and reinfestation. In true resistance, a different pediculicide class should be used, e.g. second-line agents such as phenothrin, malathion or ivermectin. Lice have existed long before humans and given their adaptability, despite habitat challenges from fashion trends in body hair removal, are likely to continue to survive.

Skin cancers in skin types IV-VI: Does the Fitzpatrick scale give a false sense of security?

The Fitzpatrick scale has been in use for skin colour typing according to the tanning potential of skin since its inception in 1975-1976. Thomas Fitzpatrick developed the scale to classify persons with 'white skin' in order to select the correct amount of UVA in Joules/cm2 for PUVA treatment for psoriasis. Since then, it has been widely used in Dermatology to gauge the skin's reaction to UV exposure, tanning potential, assessment of sunburn risk and amount of sun protection required for individual patients. However, the use of this scale has been of limited utility because of different self-perception in different areas of the world, particularly among those with skin of colour. Skin cancer risk is loosely inversely correlated with the initial genetic/inherent amount of melanin (most research has focused on eumelanin) present in the skin, although the pattern of exposure and amount of UV radiation required causing DNA damage varies widely according to different cancers. In this review, we have shown that the Fitzpatrick scale is neither correct nor adequate to reflect sunburn and tanning risk for skin of colour. Therefore, it may give both patients and physicians a false sense of security that there is little risk that people of colour can develop skin cancers. We have reviewed the small but not insignificant risk of skin of colour developing skin cancers and emphasise that there remains much research that needs to be done in this field.

Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare neuroendocrine carcinoma. The cellular origin of MCC may include Merkel cell precursors. The incidence of MCC has increased significantly however trends may have been confounded by evolving diagnostic criteria. The two key aetiologies of MCC are ultraviolet radiation and Merkel cell polyoma virus (MCPyV). Both have unique mechanisms of carcinogenesis. MCC presents non-specifically as a rapidly growing, red-to-violet nodule on sun-exposed areas. Diagnostic accuracy has improved through immunohistochemical markers such as CK-20. Lymph nodes should be evaluated in MCC through examination and sentinel biopsy. USS, CT, MRI and CT-PET may be useful in staging. Management depends on tumour location, stage and comorbidities. MCPyV status may guide treatment strategy in the future. Treatment for the primary MCC is commonly wide local excision followed by radiotherapy, guided by anatomical constraints. There is uncertainty about surgical margins. Treatments for nodal disease have not been determined through trials. They include nodal dissection or radiotherapy for clinically or radiologically apparent disease, and adjuvant nodal irradiation for negative nodes, microscopic disease or following nodal dissection for definite disease. Patients with loco-regional advanced inoperable disease should be considered for combination therapy including chemotherapy, radiotherapy, surgery and immunotherapy. Systemic therapy for advanced disease includes immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway. Avelumab can improve survival in metastatic MCC. Immunotherapy may result in longer disease control. Various other immunotherapeutic and molecular agents are undergoing trials. MCC continues to have a high mortality characterized by high recurrence and early metastases.

Clinical response to antibiotic regimens in lower limb cellulitis: a systematic review.

There is variation in the treatment of lower limb cellulitis (LLC) with no agreement on the most effective antibiotic regimen. Many patients with cellulitis fail to respond to first-line antibiotics. This can negatively affect patient care and result in unnecessary hospital admissions. The aim of this systematic review was to determine the clinical response and safety of antibiotic regimens for the management of LLC. A systematic review for randomized controlled trials (RCTs) was conducted using OVID MEDLINE, Ovid Embase and Cochrane Central Register of Controlled Trials in January 2019. Outcomes of interest included the clinical response to antibiotic regimens (type, dose, route, duration) and the safety of antibiotics in LLC. Trial quality was identified using the Cochrane Risk of Bias tool. Four RCTs were included. All included studies showed no significant differences between the clinical response to different antibiotic type, administration route, treatment duration or dose. LLC may be overtreated and shorter courses of oral antibiotics, possibly with lower doses, may be more suitable. There is a lack of published data on the clinical response and safety of antibiotics in LLC. Three studies were high risk for bias overall. Further high-quality studies may help determine whether less intensive antibiotic regimens can effectively treat LLC.

Randomized controlled trial of topical corticosteroid and home-based narrowband ultraviolet B for active and limited vitiligo: results of the HI-Light Vitiligo Trial.

BACKGROUND: Evidence for the effectiveness of vitiligo treatments is limited. OBJECTIVES: To determine the effectiveness of (i) handheld narrowband UVB (NB-UVB) and (ii) a combination of potent topical corticosteroid (TCS) and NB-UVB, compared with TCS alone, for localized vitiligo. METHODS: A pragmatic, three-arm, placebo-controlled randomized controlled trial (9-month treatment, 12-month follow-up). Adults and children, recruited from secondary care and the community, aged ≥ 5 years and with active vitiligo affecting < 10% of skin, were randomized 1 : 1 : 1 to receive TCS (mometasone furoate 0·1% ointment + dummy NB-UVB), NB-UVB (NB-UVB + placebo TCS) or a combination (TCS + NB-UVB). TCS was applied once daily on alternating weeks; NB-UVB was administered on alternate days in escalating doses, adjusted for erythema. The primary outcome was treatment success at 9 months at a target patch assessed using the participant-reported Vitiligo Noticeability Scale, with multiple imputation for missing data. The trial was registered with number ISRCTN17160087 on 8 January 2015. RESULTS: In total 517 participants were randomized to TCS (n = 173), NB-UVB (n = 169) and combination (n = 175). Primary outcome data were available for 370 (72%) participants. The proportions with target patch treatment success were 17% (TCS), 22% (NB-UVB) and 27% (combination). Combination treatment was superior to TCS: adjusted between-group difference 10·9% (95% confidence interval 1·0%-20·9%; P = 0·032; number needed to treat = 10). NB-UVB alone was not superior to TCS: adjusted between-group difference 5·2% (95% CI - 4·4% to 14·9%; P = 0·29; number needed to treat = 19). Participants using interventions with ≥ 75% expected adherence were more likely to achieve treatment success, but the effects were lost once treatment stopped. Localized grade 3 or 4 erythema was reported in 62 (12%) participants (including three with dummy light). Skin thinning was reported in 13 (2·5%) participants (including one with placebo ointment). CONCLUSIONS: Combination treatment with home-based handheld NB-UVB plus TCS is likely to be superior to TCS alone for treatment of localized vitiligo. Combination treatment was relatively safe and well tolerated but was successful in only around one-quarter of participants.

A Systematic Review of Model-Based Economic Evaluations of Treatments for Venous Leg Ulcers.

OBJECTIVE: The aim of this review was to identify, and assess the quality of, published model-based economic evaluations relating to treatments for patients with venous leg ulcers to help inform future decision-analytic models in this clinical area. METHODS: A systematic literature search was performed on six electronic databases, from database inception until 21 May 2018. Search results were screened against predefined criteria by two independent reviewers. Data was then extracted from the included studies using a standardised form, whilst the decision-analytic model-specific Philips Checklist was used to assess quality and to inform model critique. RESULTS: A total of 23 models were identified, 12 studies used a Markov modelling approach, five used decision trees and six studies did not detail the model type. Studies were predominantly from the National Health Service (NHS)/payer perspective, with only two taking a societal perspective. Interventions were wide ranging, but dressing technologies (11/23) were most common. The intervention studied was found to be dominant in 22/23 studies. The reporting quality of papers was mostly low, with evidence behind model structures, time horizons and data selection consistently underreported across the included papers. CONCLUSIONS: This review has identified a sizeable literature of model-based economic evaluations, evaluating treatments for venous leg ulcers. However, the methods used to conduct such studies were generally poorly reported. In particular, the reporting of evidence surrounding the model structure, justification of the time horizon used and the rationale for selecting data inputs should be focused on in any future models developed.

A review of trench foot: a disease of the past in the present.

From the French Invasion of Russia in 1812, to Glastonbury festival in 2007, trench foot has been reported, yet the exact nature of the condition remains unclear. This review explores the pathogenesis and treatment of trench foot. Trench foot is considered to be a nonfreezing cold injury often complicated by infection, in which exposure to cold temperatures just above freezing, combined with moisture, results in a peripheral vasoneuropathy. The presence of physical trauma, bacterial or fungal infections, malnutrition, venous hypertension and lymphoedema mean that some individuals are at greater risk of trench foot. Trench foot may be prevented by warming the feet, changing socks, staying active, rubbing the skin with oil and regularly inspecting the feet. Avoiding risk factors may help prevent the condition. The management of trench foot is less clear. Vasodilators such as iloprost and nicotinyl tartrate or sympathectomy may help. Trench foot may lead to necrosis, cellulitis, sepsis and amputation. It remains a poorly understood condition.

An introduction to the methods of decision-analytic modelling used in economic evaluations for Dermatologists.

Economic evaluations are used to identify which health treatments or preventions offer the most effective use of resources, or value for money. This is achieved by identifying, measuring and valuing the inputs and outcomes of alternative interventions. These evaluations are often conducted alongside clinical trials; however, these trials may end before the outcomes of economic interest have been observed and measured. An alternative to within trial economic evaluation is to use decision modelling, which can model the cost-effectiveness of interventions over an extended time period. This paper aims to provide an overview for clinicians of the different modelling techniques used within health economic evaluations and to introduce methods for critical appraisal. The most common modelling approaches, and their associated strengths and weaknesses, were discussed. Alongside this, practical examples specific to dermatology were given. These examples include studies where the model chosen or the methods used may not have been the most appropriate. Methods for critical appraisal were also highlighted. Common modelling approaches include Decision Trees, Markov Cohort, extensions to the Markov model (Monte Carlo Simulation) and Discrete Event Simulation models. Items of the Philips Checklist were discussed in the context of performing critical appraisal. Health economic decision models are multi-faceted and can often be complex. Full critical appraisal requires clinicians' unique knowledge, which is complementary to the knowledge of health economists.

A systematic review showing the lack of diagnostic criteria and tools developed for lower-limb cellulitis.

BACKGROUND: Cellulitis can be a difficult diagnosis to make. Furthermore, 31% of patients admitted from the emergency department with suspected lower-limb cellulitis have been misdiagnosed, with incorrect treatment potentially resulting in avoidable hospital admission and the prescription of unnecessary antibiotics. OBJECTIVES: We sought to identify diagnostic criteria or tools that have been developed for lower-limb cellulitis. METHODS: We conducted a systematic review using Ovid MEDLINE and Embase databases in May 2018, with the aim of describing diagnostic criteria and tools developed for lower-limb cellulitis, and we assessed the quality of the studies identified using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. We included all types of study that described diagnostic criteria or tools. RESULTS: Eight observational studies were included. Five studies examined biochemical markers, two studies assessed imaging and one study developed a diagnostic decision model. All eight studies were considered to have a high risk for bias in at least one domain. The quantity and quality of available data was low and results could not be pooled owing to the heterogeneity of the findings. CONCLUSIONS: There is a lack of high-quality publications describing criteria or tools for diagnosing lower-limb cellulitis. Future studies using prospective designs, validated in both primary and secondary care settings, are needed. What's already known about this topic? Diagnosing lower-limb cellulitis on first presentation is challenging. Approximately one in three patients admitted from the emergency department with suspected lower-limb cellulitis do not have cellulitis and are given another diagnosis on discharge. Consequently, this results in potentially avoidable hospital admissions and the prescription of unnecessary antibiotics. There are no diagnostic criteria available for lower-limb cellulitis in the U.K. What does this study add? This systematic review has identified a key research gap in the diagnosis of lower-limb cellulitis. There is a current lack of robustly developed and validated diagnostic criteria or tools for use in clinical practice.

Understanding economic evidence for the prevention and treatment of atopic eczema.

BACKGROUND: Atopic eczema is an inflammatory skin condition, with a similar impact on health-related quality of life as other chronic diseases. Increasing pressures on resources within the National Health Service increase the importance of having good economic evidence to inform their allocation. OBJECTIVES: To educate dermatologists about economic methods with reference to currently available economic evidence on eczema. METHODS: The role of different types of economic evidence is illustrated by evidence found in a systematic literature search conducted across 12 online databases up to 22 May 2017. Primary empirical studies either reporting the results of a cost-of-illness study or evaluating the cost, utility or full economic evaluation of interventions for preventing or treating eczema were included. Two reviewers independently assessed studies for eligibility and performed data abstraction, with disagreements resolved by a third reviewer. Evidence tables of results were produced for narrative discussion. The reporting quality of economic evaluations was assessed. RESULTS: Seventy-eight studies (described in 80 papers) were deemed eligible. Thirty-three (42%) were judged to be economic evaluations, 12 (15%) cost analyses, six (8%) utility analyses, 26 (33%) cost-of-illness studies and one a feasibility study (1%). The calcineurin inhibitors tacrolimus and pimecrolimus, as well as barrier creams, had the most economic evidence available. Partially hydrolysed infant formula was the most commonly evaluated prevention. CONCLUSIONS: The current level of economic evidence for interventions aimed at preventing and treating eczema is limited compared with that available for clinical outcomes, suggesting that greater collaboration between clinicians and economists might be beneficial.