Confocal microscopy for healthy and pathological nail

Nail diseases are often annoying for the patient and diagnostically challenging for dermatologists. New imaging techniques are of high interest in the diagnosis of nail disorders to reduce the number of nail biopsies. Confocal microscopy is a high‐resolution emerging imaging technique that can be used to explore the entire body surface, including skin, mucosa, hair and nails. A systematic review of the literature concerning the use of confocal microscopy for the study of either healthy or pathological nail has been performed to evaluate the current use of this technique and possible future applications. Confocal microscopy is particularly suitable for nails because it allows a non‐invasive in vivo examination of this sensitive body area, and nail plate transparency permits to image up to the nail bed with an easy identification of corneocytes. Confocal microscopy can play a role in the diagnosis of onychomycosis and melanonichia, and in the study of drug penetration through the nail plate. It could be used in the future as a non‐invasive procedure for the investigation of different nail diseases, such as psoriasis and lichen planus. Further application could be the intra‐operative ex vivo examination of nail specimens to outline tumour margins to assist surgery.     

High‐definition optical coherence tomography – an aid to clinical practice and research in dermatology

At present, beyond clinical assessment, the diagnosis of skin diseases is primarily made histologically. However, skin biopsies have many disadvantages, including pain, scarring, risk of infection, and sampling error. With recent advances in skin imaging technology, the clinical use of imaging methods for the practical management of skin diseases has become an option. The in vivo high‐definition optical coherence tomography (HD‐OCT) has recently been developed and commercialized (Skintell®; Agfa, Belgium). Compared with conventional OCT, it has a higher resolution; compared with reflectance confocal microscopy, it has a shorter time for image acquisition as well as a greater penetration depth and a larger field of view. HD‐OCT is promising but much work is still required to develop it from a research tool to a valuable adjunct for the noninvasive diagnosis of skin lesions. Substantial work has been done to identify HD‐OCT features in various diseases but interpretation can be time‐consuming and tedious. Projects aimed at automating these processes and improving image quality are currently under way.     

Optische Kohärenztomographie für die schnelle Bildgebung,Beurteilung und Überwachung entzündlicher Autoimmunerkrankungen der Haut am Krankenbett?

Optical coherence tomography (OCT) is a non‐invasive, high‐resolution imaging technique with a growing impact in dermatology. The principle of OCT is comparable to that of sonography, except that it uses infrared laser light instead of ultrasound waves. It has been clinically demonstrated that OCT is suitable for discriminating between different types of non‐melanoma skin cancer at an early stage of disease. Optical coherence tomography generates two‐ or three‐dimensional images of up to 2 mm penetration depth, a field of view of 6 mm × 6 mm, and an acquisition time of seconds. The resolution capability of OCT is more than 3 to 100 times higher than that of ultrasound imaging. It is of particular interest that the additional information on vasculature provided by OCT angiography enables the assessment and monitoring of inflammatory skin diseases. The use of OCT to locate exact blister levels was demonstrated for diagnosing autoimmune bullous diseases. It is anticipated that detection of subclinical lesions could indicate a relapse of the disease. In the future, this could enable intervention and early treatment. Furthermore, the development of high‐speed OCT could allow fast scanning and bedside imaging of large body sites.     

IgG4‐related disease with cutaneous manifestations treated with rituximab: Case report and literature review

Immunoglobulin type gamma 4 (Ig)G4‐related disease (IgG4‐RD) is a relatively recently described clinical entity characterised by elevated levels of serum IgG4 and tissue infiltration of IgG4+ plasma cells in various organ systems. Cutaneous involvement is rare but is becoming increasingly appreciated; typically presenting as erythematous papules and/or nodules that are commonly pruritic. We report a case of IgG4‐RD presenting with persistent pruritic papules and unilateral parotid swelling. His serum IgG4 level was elevated and a histological examination of his skin biopsies found a lymphoplasmacytic infiltration with an excess of IgG4+ non‐clonal plasma cells. The patient was intolerant of oral prednisolone, however complete resolution of the cutaneous lesions was achieved with the anti‐CD20 antibody, rituximab.     

Tolerance of low‐frequency ultrasound sonophoresis: a double‐blind randomized study on humans

Background: Sonophoresis [low‐frequency ultrasound (US)] has been used in animals and in vitro to investigate enhanced percutaneous absorption of drugs. No study focused on its clinical human tolerance has been published as yet. Methods: We aimed to assess the bioeffects of low‐frequency US in vivo on human skin in a double‐blind randomized‐controlled study. We applied pulse‐mode US at 36 kHz for 5 min in a step procedure of increasing dosage, from 1.57 to 3.50 W/cm², and placebo. The primary outcome was toxic effects of the procedure, defined as a pain score >40 on a 0–100 mm visual analogue scale or necrosis. Erythema (scored from 0 to 3 in severity) was also evaluated. The secondary outcomes were measurements of skin thickness by high‐resolution skin imaging, of skin capacitance and temperature. Results: We included 34 healthy volunteers. We found no pain score >38 and no skin necrosis with either US or placebo. Erythema was systematically observed immediately after US application, but after 1 day, we observed three cases in the knee group. The most frequent adverse effect was tinnitus. We observed no marked increase in temperature or cutaneous thickness after US or placebo. Cutaneous capacitance increased immediately after both applications. Conclusion: Such data demonstrating good tolerance of sonophoresis can be useful before the initiation of a clinical trial of the therapeutic use of low‐frequency sonophoresis in humans.     

Cutaneous lesions of Kikuchi's disease: Evolution of histopathological findings

We report a 38‐year‐old male patient who presented with cutaneous lesions mimicking widespread discoid lupus erythematosus with high‐grade fever, arthralgia and lymphadenopathy. Additional lymph node and skin biopsies, however, revealed karyorrhectic debris without neutrophils and numerous CD68‐positive cells, a characteristic finding of Kikuchi's disease (KD). Comparing skin biopsies on different occasions, we could see different forms of histopathology. The histopathology of skin lesions of KD may vary during the clinical course, which may reflect the stage of the disease.     

Ultrasound findings in idiopathic facial aseptic granuloma: Case series and literature review

Idiopathic facial aseptic granuloma is an inflammatory nodule commonly located on the cheeks and eyelids in young children. Despite its prolonged course, it tends toward spontaneous resolution, so invasive diagnostic procedures should be avoided. Cutaneous ultrasound is a noninvasive modality that has been found to improve the diagnostic accuracy of nodular skin lesions. We report five children with idiopathic facial aseptic granuloma in whom high‐resolution ultrasound examination provided distinctive findings.     

High‐definition optical coherence tomography enables visualization of individual cells in healthy skin: comparison to reflectance confocal microscopy

High‐definition OCT (HD‐OCT) is an innovative technique based on the principle of conventional OCT. Our objective was to test the resolution and image quality of HD‐OCT in comparison with reflectance confocal microscopy (RCM) of healthy skin. Firstly, images have been made of a ultra‐high‐resolution line‐pair phantome with both systems. Secondly, we investigated 21 healthy volunteers of different phototypes with HD‐OCT and RCM on volar forearm and compared the generated images. HD‐OCT displays also differences depending on the skin phototype and anatomical site. The 3‐μm lateral resolution of the HD‐OCT could be confirmed by the phantom analysis. The identification of cells in the epidermis can be made by both techniques. RCM offers the best lateral resolution, and HD‐OCT has the best penetration depth, providing images of individual cells deeper within the dermis. Eccrine ducts and hair shafts with pilosebaceous units can be observed depending on skin site. HD‐OCT provides morphological imaging with sufficient resolution and penetration depth to permit visualization of individual cells at up to 570 μm in depth offering the possibility of additional structural information complementary to that of RCM. HD‐OCT further has the possibility for rapid three‐dimensional imaging.     

Pre‐operative ultrasound with a 12–15 MHz linear probe reliably differentiates between melanoma thicker and thinner than 1 mm

Background Pre‐operative determination of primary melanoma thickness could be a tool to identify those patients who could be treated with radical primary tumour excision and sentinel lymph node biopsy in a single procedure. An excellent correlation between sonographic and histological measurement of maximal tumour thickness has been achieved using 20‐MHz transducers. Objective To show that widely available high resolution ultrasound with 12–15 MHz linear probe could also reliably assess the thickness of primary melanoma. Methods Sixty‐nine patients underwent ultrasound evaluation of 70 clinically and dermoscopically suspicious pigmented skin lesions before surgical excision. Results The sensitivity, specificity, positive and negative predictive values of ultrasound to detect melanoma > 1 mm were 92%, 92%, 95% and 81% respectively. The correlation between ultrasound and histological tumour thickness was very good [Pearson’s correlating index 0.823 (P < 0.001)]. Mean difference between sonographic and histological measurements was 0.045 mm with limits of agreement estimated at ?1.4 and +1.49, and a bias between two methods 45 μm. Conclusion Ultrasound examination with a 12–15 MHz linear transducer can reliably differentiate primary melanoma > 1 mm from those ≤ 1 mm.     

Advances in non‐invasive techniques as aids to the diagnosis and monitoring of therapeutic response in plaque psoriasis: a review

Plaque psoriasis is a common, chronic, inflammatory disease with a multifactorial etiopathogenesis. Although its diagnosis is often based on clinical features, in ambiguous cases a biopsy with histopathologic confirmation may be necessary. Advanced high‐definition imaging techniques may be useful in the study of skin properties in vivo and may facilitate therapeutic monitoring. Available imaging tools vary in their resolution, depth of penetration and visual representation (horizontal, vertical, three‐dimensional), and in the type of skin structures visualized. The purpose of this review is to analyze a variety of non‐invasive techniques that may assist in establishing definitive diagnoses, as well as in the therapeutic monitoring of psoriasis. These include dermoscopy, videocapillaroscopy (VC), high‐frequency ultrasound (HFUS), reflectance confocal microscopy (RCM), laser Doppler imaging (LDI), optical coherence tomography (OCT), optical microangiography (OMAG) and multiphoton tomography (MPT). Their characteristics, indications, advantages, and limits are reviewed and discussed. Dermoscopy may be useful for a first, rapid outpatient evaluation. Videocapillaroscopy and HFUS represent the imaging techniques with the longest history of use in psoriasis. However, whereas VC is useful in both diagnosis and therapeutic monitoring, the utility of HFUS appears to be limited to the monitoring of response to therapy only. Both devices are cost‐effective and easy to use in the office setting. Both RCM and OCT allow high‐resolution microscopic imaging of psoriatic plaque in a manner comparable with that of virtual histopathology and represent more promising techniques. The utility of LDI, OMAG, and MPT in psoriasis skin imaging requires further study and validation.     

Electron paramagnetic resonance (EPR) imaging in skin: biophysical and biochemical microscopy.

Electron paramagnetic resonance (EPR) is a spectroscopic technique that allows detection of paramagnetic compounds, e.g., free radicals, in skin, and is used for measuring skin membrane fluidity and polarity. EPR imaging is concerned with spatially resolved EPR spectroscopy. We studied EPR images at X-band frequency (9 GHz) in the skin biopsies of hairless mice. Our particular imaging technique utilized a modulated field gradient to obtain cross-sectional images perpendicular to the skin surface. Employing nitroxide free radicals, this approach allows analysis of skin biophysical and biochemical features at the micrometer resolution level. By spin labeling drugs, pharmacokinetic properties of the labeled compound can be monitored in skin. We suggest that EPR imaging has a broad application potential in dermatologic research. In comparison to other spatially visualizing techniques, such as nuclear magnetic resonance (NMR) imaging and ultrasound, EPR imaging has significant advantages, such as high spatial resolution and providing specific biochemical and biophysical information that cannot be obtained by other methods in skin.     

External vascular compression by hyaluronic acid filler documented with high‐frequency ultrasound

We present a case report of a hyaluronic acid filler‐induced complication documented using high‐frequency ultrasound. We regard the scientific value of the case as indicating the benefit that ultrasound provides for the management and documentation of this complication. This technology has been becoming increasingly widespread in the care of patients who experience unwanted effects of hyaluronic acid filler because it can be used for the high‐resolution visualization of skin layers as well as the differentiation of filler types and their relationships with adjacent tissues (via gray scale or B‐mode ultrasound) and blood vessels (via color Doppler ultrasound). In addition, it was possible to conclude that external vascular compression causes clinical repercussions, a fact that is often questioned by some dermatologists. This questioning is based on the vast vascularization and anastomosis of arteries of the face, which should permit compensation for vascular compression. However, in this case, there was no doubt that compression caused a region of low output with the clinical manifestation of peri‐oral pallor. Ultrasound was used to document the compression of a vessel by the filler; after application of hyaluronidase, increased vessel lumen and clinical reversal of hypoperfusion in the affected area were observed.     

Tissue expansion: update and prospects

This brief history of the development of the tissue expansion technique, from the initial intuitions of C.G. Neumann to the later applications by C. Radovan and subsequent uses, includes notes on the surgical techniques involved and the structural modifications of expanded skin. The author explains his preference for use of the external valve expander and presents data regarding use of high resolution ultrasound to monitor the thickness of expanded tissues. Dermatologists as well as surgeons should be familiar with the possible uses of this technique in the treatment of various wounds and skin lesions.     

High‐frequency ultrasound evaluation of cellulite treated with the 1064 nm Nd:YAG laser

Objectives: To investigate non‐invasive laser treatment for cellulite using the 1064?nm Nd:YAG laser and to correlate clinical results with high‐frequency skin ultrasound images. Methods: Twelve individuals of normal weight were treated on either the left or right posterior side of the thigh with the following parameters: fluence 30?J/cm, 18?mm spot size and dynamic cooling device pulse duration of 30?ms. Three treatments were performed at intervals of 3–4 weeks, and followed‐up 1 and 3 months after the last session. Photographs and ultrasound imaging were assessed before each session. Results: The 1064?nm Nd:YAG laser resulted in a tightening of the skin and an improvement in cellulite. No side effects were reported. High‐resolution ultrasound imaging showed a significant improvement in dermis density and a reduction of dermis thickness. The method is described in detail in Appendix 1. Conclusion: Infra‐red lasers may constitute a safe and effective treatment for cellulite and high‐frequency ultrasound imaging provides a quantitative and objective measurement of the treatment efficacy.     

High-frequency ultrasound imaging of the skin during normal and hypertensive pregnancies

Background/aims: Diagnosis of preeclampsia is currently made from blood pressure measurements taken at antenatal visits (either at the hospital or in the community). The aim of this work was to see whether the presence of underlying hypertensive diseases is accompanied by changes in the skin of pregnant women, which can be visualized using high‐frequency diagnostic ultrasound. Method: This was a prospective study of pregnant and non‐pregnant, hypertensive and non‐hypertensive patients visiting the outpatient department of a central London Teaching Hospital. The study group consisted of 93 women, of which 30 were non‐hypertensive in the second trimester of pregnancy, 26 were non‐hypertensive in the third trimester of pregnancy, 9 were hypertensive in the second trimester of pregnancy, and 14 were hypertensive in the third trimester of pregnancy. Fourteen non‐pregnant women of comparable age were recruited as controls. Changes in abdominal skin thickness and also skin structure, as analysed by fractal image analysis, was assessed in each patient. Results: In a normal pregnancy, abdominal skin gets thinner as pregnancy progresses. In hypertensive patients, the skin thickness did not appear to alter. Image analysis of abdominal skin scans showed that the skin of non‐hypertensive pregnant women and non‐pregnant women are different. Whereas the analysis of hypertensive pregnant women and non‐pregnant women showed they were the same. Conclusions: The data used to compare the groups indicates that if the abdominal skin of the patient does not get thinner as the pregnancy progresses there is an indication that the patient may be hypertensive. The fractal data comparing the groups indicates the following when comparing a patient’s fractal signature with the non‐pregnant control data: If the abdominal fractal for a pregnant woman is similar to the control group, there is an indication that the patient is hypertensive. It is difficult to predict hypertension in patients, and it is possible that a patient could develop severe preeclampsia between visits to the antenatal clinics. Therefore, if the high‐frequency ultrasound scanner can pick up potential hypertensives early in pregnancy, these women could be identified as potentially high risk.     

In vivo reflectance confocal microscopy detects pigmentary changes in melasma at a cellular level resolution

Please cite this paper as: In vivo reflectance confocal microscopy detects pigmentary changes in melasma at a cellular level resolution. Experimental Dermatology 2010; 19 : e228–e233. Abstract: Melasma is a frequent pigmentary disorder caused by abnormal melanin deposits in the skin. In vivo reflectance confocal microscopy (RCM) is a repetitive imaging tool that provides real‐time images of the skin at nearly histological resolution. As melanin is the strongest endogenous contrast in human skin, pigmentary disorders are the most suitable candidates for RCM examination but RCM features of melasma have never been reported. This study investigates the pilot use of RCM in melasma to provide a set of well‐described morphological criteria with histological correlations. RCM images were acquired from melasma skin and compared to adjacent control skin in 26 patients. Skin biopsies were obtained from eight patients. In the epidermis, RCM showed in all patients a significant increase in hyperrefractile cobblestoning cells. These cells corresponded to hyperpigmented basal keratinocytes in histology. In six patients, dendritic cells corresponding to activated melanocytes were also found in the epidermis. In the dermis, RCM identified in nine patients plump bright cells corresponding to melanophages. Interestingly, for a given patient, the topographic distribution of melanophages in melasma lesions was very heterogeneous. RCM also showed a significant increase in solar elastosis and blood vessels in the dermis. RCM is a non‐invasive technique that detects pigmentary changes in melasma at a cellular level resolution. Therefore, RCM provides an innovative way to classify melasma by pigment changes.     

Imaging actinic keratosis by high‐definition optical coherence tomography. Histomorphologic correlation: a pilot study

With the continued development of non‐invasive therapies for actinic keratosis such as PDT and immune therapies, the non‐invasive diagnosis and monitoring become increasingly relevant. High‐definition optical coherence tomography is a high‐resolution imaging tool, with micrometre resolution in both transversal and axial directions, enable to visualize individual cells up to a depth of around 570 μm filling the imaging gap between conventional optical coherence tomography and reflectance confocal microscopy. We sought to determine the feasibility of detecting and grading of actinic keratosis by this technique using criteria defined for reflectance confocal microscopy compared to histology. In this pilot study, skin lesions of 17 patients with a histologically proven actinic keratosis were imaged by high‐definition optical coherence tomography just before excision and images analysed qualitatively. The surrounding normal looking skin has been used as control group. In lesional skin, dyskeratotic and atypical keratinocytes could be noticed with this new technique. An atypical honeycomb pattern in variable degree or a disarranged epidermal pattern could be observed. A good correlation between the dimension of atypia and/or disarrangement of the spinous–granular layer on en face images and the histopathological grading could be demonstrated. Relevant cross‐sectional imaging criteria could be defined for the different histopathological variants of actinic keratoses. The surrounding skin displayed features of photodamage. Using features already suggested by reflectance confocal microscopy, the study implies that high‐definition optical coherence tomography facilitates in vivo diagnosis of actinic keratosis and allows the grading of different actinic keratosis lesions for increased clinical utility.     

Reflectance confocal microscopy for pigmentary disorders

Please cite this paper as: Reflectance confocal microscopy for pigmentary disorders. Experimental Dermatology 2010; 19: 233–239. Abstract: In vivo reflectance confocal microscopy (RCM) is a non‐invasive, repetitive imaging tool that provides real‐time images at nearly cellular histological resolution. Application of this technology to skin imaging during the last decade has been a great advance in dermatology. As melanin is the strongest endogenous contrast in human skin, pigmentary disorders caused by abnormal amounts of melanin in the skin could be the most suitable candidates for RCM examination. This article reviewed the RCM applications in the characterization and management of pigmentary disorders. The application of RCM in pigmentary disorders has been expanded to describe hyper‐ and hypopigmentary disorders as well as pigmented skin tumors. The great advantages of non‐invasive and repetitive examination of RCM may provide its usefulness not only in the diagnosis and management of pigmentary disorders, but also in researching pathogenesis of pigmentary disorders.     

Objective assessment of dermal fibrosis in cutaneous scarring,using optical coherence tomography,high-frequency ultrasound and immunohistomorphometry of human skin

The wound healing process can result in the formation of a scar, which replaces normal tissue after injury. Many scar treatments are available but none can totally erase a scar and many can result in a poor outcome. Therefore, in order to evaluate current treatments, as well as research to develop new methods for treating scars, devices which give numerical values at each stage of wound healing are needed. Assessing skin fibrosis (scarring) remains a challenge. This study therefore aimed to find out if high frequency ultrasound (HFUS) and optical coherence tomography (OCT) devices were able to provide a numerical indicator (score) of skin fibrosis over the course of wound healing. This was achieved by recruiting 62 healthy volunteers in Manchester, United Kingdom and carrying out small skin biopsies to their upper inner arms over eight weeks. They had measurements taken each week by HFUS and OCT and this was supported by laboratory analysis. Both devices were able to provide numerical measurements for skin thickness and this was shown to be similar to laboratory measurements. The device software also gave measurements that linked with the amount of collagen in the skin (which gives skin its structure). This was supported by laboratory analysis of different types of collagen. Both techniques were able to identify different structures within the skin but at different depths and resolutions depending upon which device was used. Skin structures were better seen by OCT due to the resolution, whilst HFUS allowed the researchers to see the deeper skin layers. In conclusion, the choice of device is important as this would depend on the type, size and depth of the wound or scar, and specific factors to be investigated or monitored.     

Characterisation of gravity-induced facial skin oedema using biophysical measurement techniques

Background/aims: In humans, the microgravity environment can be expected to induce swelling of facial tissues and shrinking of the tissues in the lower limbs, together with a loss in body weight. To evaluate fluid shifts in skin, the head‐down bed‐rest model was used. The aim of the present study was to evaluate the appearance of facial oedema in subjects undergoing anti‐orthostatic bed‐rest at an angle of ?10°. Methods: The forehead of each of four subjects was measured before and after 1, 10 and 24 h in this head‐down tilt position. At these time points, interstitial fluid migration and facial oedema were assessed using a high resolution B‐scan ultrasound and a device for measuring the skin's mechanical properties. Results: The results obtained showed a progressive increase in dermal thickness and initial stress, and a reduction in stiffness and elasticity of the skin during the study period. Conclusions: This preliminary study has demonstrated the feasability of the method in measuring fluid displacement and retention in the skin. Furthermore, it highlights the influence of fluids on the mechanical behaviour of the skin. These techniques could be used for studying the redistribution of liquid masses during periods spent in space.