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Summary Background Nail disorders can be diagnostically challenging to the dermatologist. Noninvasive methods might help to avoid nail biopsies. More knowledge of the typical features of healthy nails with these techniques is needed for comparison with nail diseases. Objectives To describe the typical morphology of healthy nails in optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM) and to examine the influence of exposure to water on OCT features, nail thickness as well as on transonychial water loss (TOWL) before and after a hand bath. Material and methods In the first part healthy nail plates were investigated with OCT and CLSM. The thickness of layers as well as structural details were defined. Secondly, in a prospective study 30 healthy volunteers conducted 10 hand baths with water within a 2-week period. Measurements of nail thickness and signal intensity by OCT as well as of the TOWL were performed over time. Results In OCT the unaffected nail plate appears as a band-like, layered structure, yet with some individual differences. In addition, CLSM is able to display single corneocytes and the integrity of their borders. Exposure to water led to a transient rise of TOWL and in nail thickness. Conclusions OCT, CLSM and TOWL offer valuable noninvasive diagnostic tools for the examination of nails. Using CLSM, microscopic features like integrity of single corneocytes can be investigated. OCT allows determination of nail plate thickness and both OCT and TOWL measurements are able to detect short-term effects after exposure to water.

Background We previously described the principal results from an observational, prospective, multicentre, clinical trial of the diagnostic value of optical coherence tomography (OCT) for basal cell carcinoma (BCC) in a clinical setting. In this trial, much additional useful information was gathered that warranted further analysis, presented here. Objectives To investigate the influence of candidate diagnostic criteria, OCT image quality, lesion location, and observer confidence and interobserver variability on the diagnostic performance of OCT, and to assess its potential use for diagnosis of BCC subtypes. Methods A total of 234 clinically unclear 'pink lesions' were evaluated in three steps: after clinical examination, after adding dermoscopy and after adding OCT. In addition to the diagnoses (including lesion subtype), observers recorded which of 15 diagnostic criteria the OCT image contained, their confidence in the diagnoses, the OCT image quality and the anatomical location of the lesion. Results Diagnostic performance of OCT did not depend on the lesion's anatomical location. Good OCT image quality was correlated with improved diagnostic performance, but diagnostic performance for lesions with mediocre image quality was still better than by clinical and dermoscopic examination. The main reason for reduced image quality was superficial scales and crusting. Observer confidence in diagnosis was correlated with diagnostic performance. Interobserver diagnostic performance was consistently higher than clinical examination and dermoscopy across all sites. BCC subtype could be determined with moderate accuracy, but further independent image markers are required. Conclusion OCT is useful in the diagnosis of BCC.

Summary Background Skin atrophy is one of the main side-effects of topical corticosteroid therapy. Although the use of high-frequency ultrasound is an established method that has been studied previously, it allows measurements of the slow-reacting dermal thickness only. Objectives To investigate the decreasing epidermal thickness, which occurs earlier, we used optical coherence tomography (OCT), a high-resolution noninvasive imaging technique, and compared it with 20-MHz ultrasound and profilometry. Patients/methods In this double-blind placebo-controlled trial 20 healthy volunteers applied four different corticosteroids and the cream base formulation as placebo to the volar part of both arms once a day over a 4-week period. The epidermal thickness, the dermal thickness and the skin surface roughness were assessed using OCT, high-frequency ultrasound and profilometry. Results Each of the three methods allowed the detection and monitoring of significant corticosteroid-induced skin atrophy and its reversibility. The changes correlated with the potency of the steroids. The epidermal thickness decreased significantly in all test areas, even in the placebo and the untreated fields. As expected, the reduction in epidermal thickness was more pronounced and could be detected earlier by OCT than the reduction of dermal thickness using ultrasound. The epidermal surface roughness investigated using profilometry showed a slight smoothing. Conclusions OCT allows a simple, fast and noninvasive in vivo measurement of the epidermal thickness. To evaluate the atrophogenic potential of corticosteroids it is more suitable than high-frequency ultrasound as epidermal thickness decreases earlier. In addition, epidermal thickness is a more sensitive indicator of steroid atrophy as the degree of thinning is much higher compared with the dermal atrophy. Profilometry might give further information; however, it would not be suitable for clinical use as the results were generally less pronounced. In the future, OCT might be useful to detect corticosteroid-induced side-effects at the beginning for monitoring the therapy.

Background Although it is known that the skin acts as a water reservoir and participates in the fluid content of the whole body, no method has been established to quantify the fluid shifts in superficial tissue. Objectives The aim of this study was to investigate changes in dermal and subcutis thickness and echodensity at the forehead and lower leg by high-frequency (20 MHz) ultrasound under various physiological conditions influencing water balance. Methods These parameters were measured in the skin of 20 healthy male volunteers at baseline and successively at 30 min after lying down, in a head-down position, after physical activity and after infusion of 10 mL kg−1 body weight of Ringer’s solution. Results Dermal thickness at the forehead showed a significant increase from baseline to a horizontal position and a further increase in the head-down position. Physical activity did not lead to further changes, whereas after fluid infusion the dermal thickness also increased markedly. The echodensity showed inverse changes, with decreasing values. The thickness of the subcutis increased slightly from baseline to a lying position and decreased in the head-down position and after fluid infusion. At the lower leg, skin thickness decreased slightly in the head-down position with elevated legs, and increased after fluid infusion. Conclusions Our results show that slight changes in the water distribution of the body influence the thickness and the echodensity of the dermis. Changes are more pronounced at the forehead than on the lower legs. Further, the fluid storage takes place mainly in the dermis and not in the subcutis. High-frequency ultrasound is able to quantify these effects and is a sensitive method for measuring fluid intake and balance during anaesthesia and therapy.

Changes in skin thickness and echodensity during the spontaneous menstrual cycle, in women taking hormonal contraceptives and pregnant women were investigated by high-frequency (20 MHz) ultrasound. Women with a spontaneous ovulatory menstrual cycle (group I), women taking one-phase contraceptives (group II), women taking three-phase contraceptives (group III) and pregnant women (group IV) were measured at the following locations: proximal and distal forearm and lower leg on both sides. The skin was investigated during three phases of the menstrual cycle: days 2-4 (phase A), days 12-14 (phase B) and days 20-22 (phase C). Oestradiol and progesterone levels were determined at each phase. The pregnant women were investigated 2 weeks prepartal and 6 weeks after delivery. Group I showed a statistically significant increase in the skin thickness from phase A to phase B, but not from phase B to phase C. Group II showed no significant changes in skin thickness, whereas the skin thickness increased from phase A to phase B in group III. In group IV, the skin was significantly thicker prepartal than after delivery. The measured echodensity showed a negative correlation with skin thickness in group III and in pregnant women. We were able to demonstrate that the status of female sex hormones influences the thickness of the skin. These results can be explained by hormone-induced water retention in the skin. Sonography at 20 MHz is able to quantify these effects, which should be considered when performing ultrasound measurement in women.