Imaging of basal cell carcinoma by high‐definition optical coherence tomography: histomorphological correlation. A pilot study

Summary Background With the continued development of noninvasive therapies for basal cell carcinoma (BCC) such as photodynamic therapy and immune therapies, noninvasive diagnosis and monitoring become increasingly relevant. High‐definition optical coherence tomography (HD‐OCT) is a high‐resolution imaging tool, with micrometre resolution in both transversal and axial directions, enabling visualization of individual cells up to a depth of around 570 μm, and filling the imaging gap between conventional optical coherence tomography (OCT) and reflectance confocal microscopy (RCM). Objectives We sought to determine the feasibility of detecting BCC by this technique using criteria defined for RCM and conventional OCT and compared with histology. Methods In this pilot study skin lesions of 21 patients with a histologically proven BCC were imaged by HD‐OCT just before excision and images analysed qualitatively. Results Features for four different BCC subtypes were described in both transverse and axial directions. In general, these features were subepidermal or intradermal aggregations of cells. These islands or trabeculae were surrounded by a less refractile border corresponding with palisading and peritumoral mucin production. There was a pronounced architectural disarray of the epidermis. A variably refractile stroma together with abundant dilated peritumoral blood vessels was present. These features were comparable with histological features for each patient. Conclusions Using features already suggested by RCM and conventional OCT, the study implies that HD‐OCT facilitates in vivo diagnosis of BCC and allows the distinction between different BCC subtypes for increased clinical utility.     

Real‐time three‐dimensional imaging of epidermal splitting and removal by high‐definition optical coherence tomography

While real‐time 3‐D evaluation of human skin constructs is needed, only 2‐D non‐invasive imaging techniques are available. The aim of this paper is to evaluate the potential of high‐definition optical coherence tomography (HD‐OCT) for real‐time 3‐D assessment of the epidermal splitting and decellularization. Human skin samples were incubated with four different agents: Dispase II, NaCl 1 M, sodium dodecyl sulphate (SDS) and Triton X‐100. Epidermal splitting, dermo‐epidermal junction, acellularity and 3‐D architecture of dermal matrices were evaluated by High‐definition optical coherence tomography before and after incubation. Real‐time 3‐D HD‐OCT assessment was compared with 2‐D en face assessment by reflectance confocal microscopy (RCM). (Immuno) histopathology was used as control. HD‐OCT imaging allowed real‐time 3‐D visualization of the impact of selected agents on epidermal splitting, dermo‐epidermal junction, dermal architecture, vascular spaces and cellularity. RCM has a better resolution (1 μm) than HD‐OCT (3 μm), permitting differentiation of different collagen fibres, but HD‐OCT imaging has deeper penetration (570 μm) than RCM imaging (200 μm). Dispase II and NaCl treatments were found to be equally efficient in the removal of the epidermis from human split‐thickness skin allografts. However, a different epidermal splitting level at the dermo‐epidermal junction could be observed and confirmed by immunolabelling of collagen type IV and type VII. Epidermal splitting occurred at the level of the lamina densa with dispase II and above the lamina densa (in the lamina lucida) with NaCl. The 3‐D architecture of dermal papillae and dermis was more affected by Dispase II on HD‐OCT which corresponded with histopathologic (orcein staining) fragmentation of elastic fibres. With SDS treatment, the epidermal removal was incomplete as remnants of the epidermal basal cell layer remained attached to the basement membrane on the dermis. With Triton X‐100 treatment, the epidermis was not removed. In conclusion, HD‐OCT imaging permits real‐time 3‐D visualization of the impact of selected agents on human skin allografts.     

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.     

In vivo optical coherence tomography imaging of human skin: norm and pathology

Background/aims: Since the majority of skin diseases are known to be accompanied by structural alterations, research efforts are focused on the development of various novel diagnostic techniques capable of providing in vivo information on the skin structure. An essential parameter here is spatial resolution. In this paper we demonstrate the capabilities of optical coherence tomography (OCT) in detecting in vivo specific features of thin and thick skin. A particular focus is made on the identification of OCT patterns typical of certain pathological processes in skin, by performing parallel histological and tomographical studies. Methods: To obtain images of the skin, we used a compact fiber OCT system developed at the Institute of Applied Physics of the Russian Academy of Sciences. A low coherence source (superluminescent diode) operated at a wavelength of 1280 nm; the output power was 0.5–2 mW. This power is low enough to conform to the ANSI safety standards for light exposure. The in‐depth resolution limited by the spectral bandwidth (40–50 nm) of the probing light was ～20 μm. The lateral resolution determined by the probe light focusing ranged from 15 to 30 μm. In this series of experiments the maximum depth of imaging did not extend beyond 1.5 mm. Obtaining images of skin regions 2–6 mm long took 2–4 s. OCT capabilities for imaging normal skin of different localization and some skin diseases were studied in 12 healthy volunteers and 24 patients. Results: OCT imaging of the skin can detect in vivo such general pathological reactions of the human body as active inflammation and necrosis. OCT is useful for in vivo diagnosis of some specific processes in the skin, including hyperkeratosis, parakeratosis and formation of intradermal cavities. OCT imaging is noninvasive and therefore allows frequent multifocal examination of skin without any adverse effects. OCT can perform monitoring of disease progress and recovery in the course of therapy. Morphometric studies, measurements of the depth and extension of skin pathology within the human body can be easily performed by OCT. Conclusions: OCT allows imaging of subsurface soft tissues with the spatial resolution of 15–20 μm, a resolution one order of magnitude higher than that provided by other clinically available noninvasive diagnostic techniques. An imaging depth of up to 1.5–2 mm, given by current OCT technology, is sufficient to examine the skin. Real time OCT imaging can provide information not only on the structure, but also on some specific features in the functional state, of tissues. OCT imaging is a noninvasive technique, i.e., OCT does not cause trauma and has no side effects since it utilizes radiation in the near infrared wavelength range at a power as low as 1 mW.     

Actinic keratosis in the en‐face and slice imaging mode of high‐definition optical coherence tomography and comparison with histology

Background Optical coherence tomography (OCT) allows real‐time, in vivo examination of nonmelanoma skin cancer. An innovative high‐definition (HD)‐OCT with a horizontal (en‐face) and vertical (slice) imaging mode offers additional information in the diagnosis of actinic keratosis (AK) and may potentially replace invasive diagnostic biopsies. Objectives To define the characteristic morphological features of AK by using HD‐OCT in the two imaging modes compared with histopathology as gold standard. Methods In total, 20 AKs were examined by HD‐OCT in the en‐face and slice imaging modes and characteristic features were described and evaluated in comparison with the histopathological findings. Furthermore, the HD‐OCT images of a subgroup of AKs were compared with those of the clinically normal adjacent skin. Results The preoperative in vivo diagnostics showed the following features in the en‐face imaging mode of HD‐OCT: disruption of stratum corneum, architectural disarray, cellular/nuclear polymorphism in the stratum granulosum/stratum spinosum, and bright irregular bundles in the superficial dermis. In the vertical slice imaging mode the following characteristics were found: irregular entrance signal, destruction of layering, white streaks and dots, and grey areas. In contrast, the clinically healthy adjacent skin showed mainly a regular epidermal ‘honeycomb’ pattern in the en‐face mode and distinct layering of the skin in the slice mode. Conclusions HD‐OCT with both the en‐face and slice imaging modes offers additional information in the diagnosis of AK compared with conventional OCT and might enhance the possibility of the noninvasive diagnosis of AK prior to treatment procedures and possibly in the monitoring of noninvasive treatment strategies.     

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.     

High-definition optical coherence tomography imaging of melanocytic lesions: a pilot study

High-definition optical coherence tomography (HD-OCT) is a non-invasive in vivo imaging technique with cellular resolution based on the principle of conventional optical coherence tomography. The objective of this study was to evaluate HD-OCT for its ability to identify architectural patterns and cytologic features of melanocytic lesions. All lesions were examined by one observer clinically and using dermoscopy. Cross-sectional HD-OCT images were compared with histopathology. En face HD-OCT images were compared with reflectance confocal microscopy (RCM). Twenty-six melanocytic lesions of 26 patients were imaged. Identification of architectural patterns in cross-sectional mode and cytologic features of pigmented cells in the epidermis, dermo-epidermal junction, papillary dermis, and superficial reticular dermis in the en face mode was possible by HD-OCT. HD-OCT provides morphological imaging with sufficient resolution and penetration depth to discriminate architectural patterns and cytologic features of pigmented cells in epidermis and dermis. The method appears to offer the possibility of additional three-dimensional structural information complementary to that of RCM, albeit at a slightly lower lateral resolution. The diagnostic potential of HD-OCT regarding malignant melanoma is not high enough for ruling out a diagnosis of malignant melanoma.     

Recellularizing of human acellular dermal matrices imaged by high‐definition optical coherence tomography

High‐definition optical coherence tomography (HD‐OCT) permits real‐time 3D imaging of the impact of selected agents on human skin allografts. The real‐time 3D HD‐OCT assessment of (i) the impact on morphological and cellular characteristics of the processing of human acellular dermal matrices (HADMs) and (ii) repopulation of HADMs in vitro by human fibroblasts and remodelling of the extracellular matrix by these cells. Four different skin decellularization methods, Dispase II/Triton X‐100, Dispase II/SDS (sodium dodecyl sulphate), NaCl/Triton X‐100 and NaCl/SDS, were analysed by HD‐OCT. HD‐OCT features of epidermal removal, dermo‐epidermal junction (DEJ) integrity, cellularity and dermal architecture were correlated with reflectance confocal microscopy (RCM), histopathology and immunohistochemistry. Human adult dermal fibroblasts were in vitro seeded on the NaCl/Triton X‐100 processed HADMs, cultured up to 19 days and evaluated by HD‐OCT in comparison with MTT proliferation test and histology. Epidermis was effectively removed by all treatments. DEJ was best preserved after NaCl/Triton X‐100 treatment. Dispase II/SDS treatment seemed to remove all cellular debris in comparison with NaCl/Triton X‐100 but disturbed the DEJ severely. The dermal micro‐architectural structure and vascular spaces of (sub)papillary dermis were best preserved with the NaCl/Triton X‐100. The impact on the 3D structure and vascular holes was detrimental with Dispase II/SDS. Elastic fibre fragmentation was only observed after Dispase II incubation. HD‐OCT showed that NaCl/Triton X‐100 processed matrices permitted in vitro repopulation by human dermal fibroblasts (confirmed by MTT test and histology) and underwent remodelling upon increasing incubation time. Care must be taken in choosing the appropriate processing steps to maintain selected properties of the extracellular matrix in HADMs. Processing HADMs with NaCl/Triton X‐100 permits in vitro the proliferation and remodelling activity of human dermal fibroblasts. HD‐OCT provides unique real‐time and non‐invasive 3D imaging of tissue‐engineered skin constructs and complementary morphological and cytological information.     

Ex vivo high‐definition optical coherence tomography of basal cell carcinoma compared to frozen‐section histology in micrographic surgery: a pilot study

Background Micrographic surgery is an established, but time‐consuming operating procedure for facial basal cell carcinoma (BCC). A new high‐definition (HD) optical coherence tomography (OCT) with high lateral and axial resolution in a horizontal (en‐face) and vertical (slice) imaging mode allows a fast and non‐invasive in vivo examination of BCC. Objectives To compare the diagnosis of BCC in excised tissue ex vivo by high‐definition optical coherence tomography (HD‐OCT) with the findings of frozen‐section histology in micrographic surgery. Methods Twenty freshly excised BCC were examined by HD‐OCT in the en‐face and slice imaging mode divided into four sections each in concordance with the four excision margins of histography, and subsequently processed for conventional micrographic evaluation. Results A total of 80 HD‐OCT images of 20 BCCs were evaluated and in 45% (9/20) HD‐OCT correlated perfectly with the histography results. The sensitivity and specificity for the 80 evaluated HD‐OCT images were 74% and 64% respectively. Conclusions High‐definition optical coherence tomography allows the postoperative identification of BCC in excised tissue ex vivo, but has still limitations in the recognition of tumour margins in comparison with the micrographic evaluation of frozen sections.     

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.     

In vivo reflectance confocal microscopy of shave biopsy wounds: feasibility of intraoperative mapping of cancer margins

Background Reflectance confocal microscopy (RCM) images skin at cellular resolution and has shown utility for the diagnosis of nonmelanoma skin cancer in vivo. Topical application of aluminium chloride (AlCl₃) enhances contrast in RCM images by brightening nuclei. Objectives To investigate feasibility of RCM imaging of shave biopsy wounds using AlCl₃ as a contrast agent. Methods AlCl₃ staining was optimized, in terms of concentration vs. immersion time, on excised tissue ex vivo. RCM imaging protocol was tested in patients undergoing shave biopsies. The RCM images were retrospectively analysed and compared with the corresponding histopathology. Results For 35% AlCl₃, routinely used for haemostasis in clinic, minimum immersion time was determined to be 1 min. We identified three consistent patterns of margins on RCM mosaic images by varying depth: epidermal margins, peripheral dermal margins, and deep dermal margins. Tumour islands of basal cell carcinoma were identified at peripheral or deep dermal margins, correlating on histopathology with aggregates of neoplastic basaloid cells. Atypical cobblestone or honeycomb patterns were identified at the epidermal margins in squamous cell carcinomas, correlating with a proliferation of atypical keratinocytes extending to biopsy margins. Conclusions RCM imaging of shave biopsy wounds is feasible and demonstrates the future possibility of intraoperative mapping in surgical wounds.     

Optische Kohärenztomographie

Optical coherence tomography (OCT) is a high-resolution imaging method for in vivo investigation of the human skin. In cross-sectional images of several millimeters length with a penetration depth of the light signal into deeper parts of the dermis, architectural details of the upper skin layers can be assessed and monitored non-invasively over time. The resolution is not high enough to visualize cellular details. Several studies have been performed using OCT to assess its significance as a diagnostic tool for dermatology. The actual technical configuration of OCT is suitable to assess therapeutic effects objectively and to observe skin changes over time.     

Validation of a diagnostic algorithm for the discrimination of actinic keratosis from normal skin and squamous cell carcinoma by means of high‐definition optical coherence tomography

Actinic keratoses (AKs) commonly arise on sun‐damaged skin. Visible lesions are often associated with subclinical lesions on surrounding skin, giving rise to field cancerization. To avoid multiple biopsies to diagnose subclinical/early invasive lesions, there is an increasing interest in non‐invasive diagnostic tools, such as high‐definition optical coherence tomography (HD‐OCT). We previously developed a HD‐OCT‐based diagnostic algorithm for the discrimination of AK from squamous cell carcinoma (SCC) and normal skin. The aim of this study was to test the applicability of HD‐OCT for non‐invasive discrimination of AK from SCC and normal skin using this algorithm. Three‐dimensional (3D) HD‐OCT images of histopathologically proven AKs and SCCs and images of normal skin were collected. All images were shown in a random sequence to three independent observers with different experience in HD‐OCT, blinded to the clinical and histopathological data and with different experience with HD‐OCT. Observers classified each image as AK, SCC or normal skin based on the diagnostic algorithm. A total of 106 (38 AKs, 16 SCCs and 52 normal skin sites) HD‐OCT images from 71 patients were included. Sensitivity and specificity for the most experienced observer were 81.6% and 92.6% for AK diagnosis and 93.8% and 98.9% for SCC diagnosis. A moderate interobserver agreement was demonstrated. HD‐OCT represents a promising technology for the non‐invasive diagnosis of AKs. Thanks to its high potential in discriminating SCC from AK, HD‐OCT could be used as a relevant tool for second‐level examination, increasing diagnostic confidence and sparing patients unnecessary excisions.     

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.     

Optical coherence tomography in dermatology: a review

Background/aims: Optical coherence tomography (OCT) is a non‐invasive technique for morphological investigation of tissue. Since its development in the late 1980s it is mainly used as a diagnostic tool in ophthalmology. For examination of a highly scattering tissue like the skin, it was necessary to modify the method. Early studies on the value of OCT for skin diagnosis gave promising results. Methods: The OCT technique is based on the principle of Michelson interferometry. The light sources used for OCT are low coherent superluminescent diodes operating at a wavelength of about 1300 nm. OCT provides two‐dimensional images with a scan length of a few millimeters (mm), a resolution of about 15 μm and a maximum detection depth of 1.5 mm. The image acquisition can be performed nearly in real time. The measurement is non‐invasive and with no side effects. Results: The in vivo OCT images of human skin show a strong scattering from tissue with a few layers and some optical inhomogeneities. The resolution enables the visualization of architectural changes, but not of single cells. In palmoplantar skin, the thick stratum corneum is visible as a low‐scattering superficial well defined layer with spiral sweat gland ducts inside. The epidermis can be distinguished from the dermis. Adnexal structures and blood vessels are low‐scattering regions in the upper dermis. Skin tumors show a homogenous signal distribution. In some cases, tumor borders to healthy skin are detectable. Inflammatory skin diseases lead to changes of the OCT image, such as thickening of the epidermis and reduction of the light attenuation in the dermis. A quantification of treatment effects, such as swelling of the horny layer due to application of a moisturizer, is possible. Repeated measurements allow a monitoring of the changes over time. Conclusion: OCT is a promising new bioengineering method for investigation of skin morphology. In some cases it may be useful for diagnosis of skin diseases. Because of its non‐invasive character, the technique allows monitoring of inflammatory diseases over time. An objective quantification of the efficacy and tolerance of topical treatment is also possible. Due to the high resolution and simple application, OCT is an interesting addition to other morphological techniques in dermatology.     

Noninvasive diagnosis in dermatology

In addition to dermoscopy, there are other imaging and biophysical methods for the noninvasive diagnosis of skin lesions. Confocal laser microscopy allows for high‐resolution imaging of the epidermis and upper dermis. It is particularly suitable in the differential diagnosis of melanocytic lesions. Optical coherence tomography (OCT) has a lower resolution compared to confocal laser microscopy but a greater depth of penetration. It is primarily used for imaging epithelial skin cancer, especially in the context of monitoring the effectiveness of nonsurgical therapies. Electrical impedance spectroscopy does not yield cutaneous images but rather provides a score based on the cellular irregularity of the skin. Multispectral analysis involves illumination of the skin with different wavelengths and likewise results in the computation of a score. Both methods are used in the differentiation of dysplastic nevi from melanoma. Other diagnostic imaging and biophysical methods are currently still in the developmental stages. By increasing the sensitivity and specificity of clinical and dermoscopic findings, the aforementioned methods bring about an improvement in noninvasive diagnosis. They allow for skin lesions to be monitored over time and therapeutic effects to be quantified. Finally, they facilitate early diagnosis of skin cancer, and help avoid unnecessary surgery of benign lesions.     

Optical coherence tomography in dermatology: technical and clinical aspects

Optical coherence tomography (OCT), a fairly new non-invasive optical real-time imaging modality, is an emergent in vivo technique, based on the interference (Michelson interferometry) of infrared radiation and living tissues, that allows high-resolution, 2- or 3-dimensional, cross-sectional visualisation of microstructural morphology of tissues. OCT provides depth-resolved images of tissues with resolution up to a few micrometers and depth up to several millimetres depending on tissue type. The investigations using OCT to assess skin structure in clinical settings started in the past decade and consequently proved that this imaging method is useful in visualizing subsurface structures of normal skin, including the epidermis, dermoepidermal junction, dermis, hair follicles, blood vessels and sweat ducts. An increasing number of papers brought evidence of the utility and the precision of OCT technology, in its different technical variants, in diagnosing and monitoring skin disorders, including malignancies and inflammatory conditions, respectively. The present comprehensive review describes and illustrates technical aspects and clinical applications of OCT methods in dermatology.     

Reflectance confocal microscopy: an effective tool for monitoring ultraviolet B phototherapy in psoriasis

Background In vivo reflectance confocal microscopy (RCM) is a novel, noninvasive imaging technique which enables imaging of skin at a cellular resolution comparable to conventional microscopy. Objectives We performed a pilot study to evaluate RCM as a noninvasive tool for monitoring ultraviolet (UV) B phototherapy in psoriasis. Methods In six patients with psoriasis, lesional and nonlesional skin was selected for RCM imaging using a standardized protocol. Well‐known histological features of psoriasis were visualized: parakeratosis, acanthosis, agranulosis, papillomatosis, presence of epidermal inflammatory cells, increased number of papillary capillaries and increased capillary blood flow. RCM imaging was performed before the first irradiation with UVB phototherapy, after nine irradiations, at clearance and 12 weeks after clearance. In four patients, 4‐mm punch biopsies were obtained and stained with haematoxylin‐eosin. Additionally, immunohistochemical staining was performed with monoclonal antibodies specific for CD31, CD3, filaggrin, K16, Ki67 and CD1a for correlation to RCM images. Results There was a high correlation between clinical, RCM and histological features. Normalization of RCM and histological features corresponded highly to clinical improvement of psoriasis. Conclusions This study is the first to establish the use of RCM as an effective tool for noninvasive monitoring of UVB phototherapy in patients with psoriasis. Potentially, RCM could be used in many other skin diseases for monitoring therapeutic response on a cellular level in a clinical or research setting.     

Optical coherence tomography imaging of bullous diseases

Background Optical coherence tomography (OCT) is a non‐invasive optical imaging technique with a micrometer resolution that may potentially offer real‐time bedside imaging of sufficient detail to allow for morphological discrimination between different types of bullae. Objective To explore the potential of OCT in bullous skin disorders by looking at a set of patients with skin blisters of known origin and study the OCT images for possible hallmarks of the blistering level. Materials and methods OCT provides cross‐sectional, tomographic images of the skin. A consecutive series of patients were recruited and their lesions imaged by OCT: 3 patients with bullous pemphigoid (BP), 1 patient with extensive bullae following burns, 1 patient with pemphigus, 1 patient with subcorneal pustular dermatosis, and a patient with Dariers disease. The latter two were included due to similarity to pemphigus with respect to the level of defect cell adhesion. Results In OCT images, BP bullae are easily depicted as dark, ovoid to round well‐demarquated areas, and BP bulla morphology is clearly different from the burn blisters and the pemphigus‐like disease with respect to the blistering level. Discussion Differentiation of epidermal and subepidermal blisters is demonstrated using OCT. The variation within pemphigoid lesions and pemphigus‐like diseases is however too subtle to allow for differential diagnosis; this may be ascribed to limited resolution. Enhanced resolution of OCT may overcome this obstacle.     

Morphology of basal cell carcinoma in high definition optical coherence tomography: en‐face and slice imaging mode,and comparison with histology

Background Optical coherence tomography (OCT) allows real‐time, in vivo examination of basal cell carcinoma (BCC). A new high definition OCT with high lateral and axial resolution in a horizontal (en‐face) and vertical (slice) imaging mode offers additional information in the diagnosis of BCC and may potentially replace invasive diagnostic biopsies. Objectives To define the characteristic morphologic features of BCC by using high definition optical coherence tomography (HD‐OCT) compared to conventional histology. Methods A total of 22 BCCs were examined preoperatively by HD‐OCT in the en‐face and slice imaging mode and characteristic features were evaluated in comparison to the histopathological findings. Results The following features were found in the en‐face mode of HD‐OCT: lobulated nodules (20/22), peripheral rimming (17/22), epidermal disarray (21/22), dilated vessels (11/22) and variably refractile stroma (19/22). In the slice imaging mode the following characteristics were found: grey/dark oval structures (18/22), peripheral rimming (13/22), destruction of layering (22/22), dilated vessels (7/22) and peritumoural bright stroma (11/22). In the en‐face mode the lobulated structure of the BCC was more distinct than in the slice mode compared to histology. Conclusion HD‐OCT with a horizontal and vertical imaging mode offers additional information in the diagnosis of BCC compared to conventional OCT imaging and enhances the feasibility of non‐invasive diagnostics of BCC.