JEADV
DOI: 10.1111/jdv.12330
REVIEW ARTICLE
Confocal microscopy for healthy and pathological nail E. Cinotti,1,* B. Fouilloux,1 J. L. Perrot,1 B. Labeille,1 C. Douchet,2 F. Cambazard1 1
Dermatology Department and 2Pathology Department, University Hospital of Saint-Etienne, Saint-Etienne, France *Correspondence: E. Cinotti. E-mail: [email protected]
Abstract 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. Received: 22 August 2013; Accepted: 6 November 2013
Conflicts of interest None declared.
Funding sources None declared.
Introduction Confocal laser-scanning microscopy (CLSM) is an emerging technique which optically sections living tissue at various depths, to image horizontal layers of the skin1 with resolution at a cellular level and without alteration of the tissue surface. Four devices dedicated to the skin are available, two work in vivo (VivaScopeâ 1500 and 3000, CALIBER, New York, USA, distributed in Europe by the company MAVIG GmbH, Munich, Germany) and two ex vivo (VivaScopeâ 2000 and 2500, CALIBER, distributed in Europe by the company MAVIG GmbH). The use of CLSM in the field of dermatology, was first reported 20 years ago.2,3 Recently, it has also been applied to the examination of skin appendages, like hairs4 and nails.5 Confocal laser-scanning microscopy is particularly interesting for the diagnosis of nail disorders because the in vivo examination could allow to reduce the number of biopsies in this sensitive body site and the ex vivo device could assist surgery intra-operatively. Moreover, nail plate transparency allows deep penetration of CLSM that can image up to the nail bed. Here, we summarize the literature on the use of confocal microscopy for the study of healthy and pathological nail.5–14 The review was performed utilizing PubMed database. Search
JEADV 2013
terms employed were ‘nail’, ‘reflectance confocal microscopy’, ‘confocal microscopy’ and ‘onychomycosis’.
Confocal microscopy and normal nails Kaufman et al.5 were the first ones to use confocal microscope to study the ultrastructure of the nail and showed that the unique properties of confocal microscope make possible to explore the capillary nailfold and the nails up to the deeper layers of the nail plate. Sattler et al.11 have recently investigated healthy nail plates with CLSM, obtaining resolution images better than those taken by Kaufman et al. using the mercury lamp confocal microscope. The depth to which the CLSM can penetrate optically corresponds to 200–300 lm for skin tissue, but is 400–500 lm11 for the nails that are more transparent, probably due to fewer cell organelles absorbing the light and the lower refractive index of the nail unit.11 CLSM is able to display single corneocytes and the integrity of their borders. The nail plate can be scanned from the surface to the lower part adjacent to the underlying nail bed. Three different layers can be differentiated by CLSM according to the intensity of the reflection (Fig. 1). The superficial layer shows a brighter reflection, followed by a zone with slightly poorer signal, followed again by a brighter zone in the deepest part. The transition to
© 2013 European Academy of Dermatology and Venereology
Cinotti et al.
2
(a)
(d)
(b)
(e)
(c)
(f)
the underlying nail bed is visible only in thin nails (
DOI: 10.1111/jdv.12330
REVIEW ARTICLE
Confocal microscopy for healthy and pathological nail E. Cinotti,1,* B. Fouilloux,1 J. L. Perrot,1 B. Labeille,1 C. Douchet,2 F. Cambazard1 1
Dermatology Department and 2Pathology Department, University Hospital of Saint-Etienne, Saint-Etienne, France *Correspondence: E. Cinotti. E-mail: [email protected]
Abstract 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. Received: 22 August 2013; Accepted: 6 November 2013
Conflicts of interest None declared.
Funding sources None declared.
Introduction Confocal laser-scanning microscopy (CLSM) is an emerging technique which optically sections living tissue at various depths, to image horizontal layers of the skin1 with resolution at a cellular level and without alteration of the tissue surface. Four devices dedicated to the skin are available, two work in vivo (VivaScopeâ 1500 and 3000, CALIBER, New York, USA, distributed in Europe by the company MAVIG GmbH, Munich, Germany) and two ex vivo (VivaScopeâ 2000 and 2500, CALIBER, distributed in Europe by the company MAVIG GmbH). The use of CLSM in the field of dermatology, was first reported 20 years ago.2,3 Recently, it has also been applied to the examination of skin appendages, like hairs4 and nails.5 Confocal laser-scanning microscopy is particularly interesting for the diagnosis of nail disorders because the in vivo examination could allow to reduce the number of biopsies in this sensitive body site and the ex vivo device could assist surgery intra-operatively. Moreover, nail plate transparency allows deep penetration of CLSM that can image up to the nail bed. Here, we summarize the literature on the use of confocal microscopy for the study of healthy and pathological nail.5–14 The review was performed utilizing PubMed database. Search
JEADV 2013
terms employed were ‘nail’, ‘reflectance confocal microscopy’, ‘confocal microscopy’ and ‘onychomycosis’.
Confocal microscopy and normal nails Kaufman et al.5 were the first ones to use confocal microscope to study the ultrastructure of the nail and showed that the unique properties of confocal microscope make possible to explore the capillary nailfold and the nails up to the deeper layers of the nail plate. Sattler et al.11 have recently investigated healthy nail plates with CLSM, obtaining resolution images better than those taken by Kaufman et al. using the mercury lamp confocal microscope. The depth to which the CLSM can penetrate optically corresponds to 200–300 lm for skin tissue, but is 400–500 lm11 for the nails that are more transparent, probably due to fewer cell organelles absorbing the light and the lower refractive index of the nail unit.11 CLSM is able to display single corneocytes and the integrity of their borders. The nail plate can be scanned from the surface to the lower part adjacent to the underlying nail bed. Three different layers can be differentiated by CLSM according to the intensity of the reflection (Fig. 1). The superficial layer shows a brighter reflection, followed by a zone with slightly poorer signal, followed again by a brighter zone in the deepest part. The transition to
© 2013 European Academy of Dermatology and Venereology
Cinotti et al.
2
(a)
(d)
(b)
(e)
(c)
(f)
the underlying nail bed is visible only in thin nails (
