Line-Field Confocal Optical Coherence Tomography: A New Skin Imaging Technique Reproducing a "Virtual Biopsy" with Evolving Clinical Applications in Dermatology

Abstract

Background: Line-field confocal optical coherence tomography is a novel technology able to reproduce a "virtual biopsy" of the skin. The aim of this review is to explore the application of line-field confocal optical coherence tomography (LC-OCT) in various skin diseases, covering skin cancers, inflammatory and infectious skin diseases, genetic diseases, cosmetic procedures, and less common disorders.

Methods: Study selection was conducted based on LC-OCT and using pertinent MeSh terms, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines from inception to March 2024; to evaluate the quality and risk of bias of studies, Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used.

Results: the search retrieved 154 papers according to the selection criteria; after removing publications by one or more of the exclusion criteria, a total of 96 studies were found to be suitable for the analysis.

Conclusions: Increasing evidence supports the use of LC-OCT as an adjunctive diagnostic tool for the in vivo diagnosis of a variety of skin tumors. As this device can be considered a "bridge" between dermoscopy and histopathology, widening applications in numerous fields of clinical dermatology, including inflammatory skin disease treatment, presurgical mapping, cosmetic procedures, and monitoring of non-invasive therapies, have been explored.

Keywords: clinical dermatology; diagnostic imaging; histology of the skin; line-field confocal optical coherence tomography; review; virtual biopsy.

Figure 1

PRISMA flowchart diagram (adapted from Page et al., 2021) [20].

Figure 2

Dermatoscopy, horizontal LC-OCT, and histopathology of compound nevus, melanoma, genital melanosis: (a) compound nevus with globular pattern (b) associated with junctional nests (yellow asterisks) in LC-OCT and (c) histopathology; (d) melanoma showing atypical network and eccentric hyperpigmented areas in dermatoscopy, (e) due to atypical junctional melanocytes (red arrows) in LC-OCT (f) clearly seen in histopathology; (g) melanosis with dermatoscopic features of parallel pattern (h) that reveals a draped pattern (yellow asterisks) in LC-OCT, (i) corresponding to hyperpigmentation of the basal keratinocytes in histopathology.

Figure 3

Dermatoscopy, vertical LC-OCT, and histopathology of superficial basal cell carcinoma (sBCC), nodular basal cell carcinoma (nBCC), and Bowen disease: (a) sBCC showing leaf-like areas and erosions in dermatoscopy, (b) identified under LC-OCT as hemispheric lobules attached to the epidermis (yellow asterisks), (c) relating to tumor islands in histopathology; (d) nBCC with arborizing micro vessels and brown structureless areas in dermatoscopy, (e) visualized as ovoid-shaped lobules separated from the epidermis (yellow asterisks) in LC-OCT, and (f) histopathology; (g) Bowen disease with dermatoscopic pattern of glomerular vessels and a scaly surface, (h) revealing hyperkeratosis and dilated vessels (red arrows) in LC-OCT, and (i) histopathology.

Figure 4

Dermatoscopy, 3D LC-OCT, and histopathology of plaque psoriasis and bullous pemphigoid: (a) plaque psoriasis with a regular distribution of red dots and white scales in dermatoscopy, (b) showing elongation of the dermal papillae (red arrows) and dilated vessels in LC-OCT (c) clearly observed in histopathology; (d) bullous pemphigoid characterized by a yellow translucent structureless area in dermatoscopy, (e) justified by a junctional split creating a bulla with floating elements in LC-OCT (white asterisk), (f) as seen in histopathology.