Diagnostic impact of reflectance confocal microscopy as a second-level examination for facial skin lesions

Abstract

Background and objective: Benign and malignant facial skin lesions may be difficult to differentiate clinically and with dermoscopy. The present study aimed to evaluate the potential utility of in vivo reflectance confocal microscopy (RCM) as a second-level examination for facial skin neoplasms.

Patients and methods: Retrospective and blinded evaluation of 160 consecutive facial lesions was carried out in two separate steps. Clinical and dermoscopic images were assessed first, followed by combined evaluation of clinical/dermoscopic and RCM images. Our study included 60 % malignant lesions, comprising 43 % melanomas, 9 % basal cell carcinomas, 5 % in situ squamous cell carcinomas and 3 % lymphomas.

Results: Ancillary RCM significantly improved diagnostic specificity for the detection of malignancy compared to clinical/dermoscopic evaluation alone (58 % vs 28 %). However, sensitivity was slightly lower for RCM-based image evaluation (93 % vs 95 %) due to misclassification of one in situ SCC and one lymphoma. In terms of melanoma diagnosis, RCM-based image evaluation was generally superior; sensitivity was only slightly increased (88 % vs 87 %), but melanoma specificity was significantly higher (84 % vs 58 %).

Conclusion: RCM is a valuable diagnostic adjunct for facial skin lesions; unnecessary biopsies in this cosmetically sensitive area could be reduced by one third without missing a melanoma.

Keywords: benign facial macules; dermatopathology; dermoscopy; face; in vivo reflectance confocal microscopy (RCM); melanoma.

Figure 1

Clinical, dermoscopic, and RCM images of a solar lentigo, destined for biopsy based on clinical/dermoscopic examination to rule out melanoma. An irregularly shaped, tan to dark‐brown macule is seen on the right cheek (a; arrow). Dermoscopy shows an ill‐defined macule with tan to dark‐brown pseudonetwork. A few gray‐brown dots (arrow) are observed in an area with eccentric hyperpigmentation, raising suspicion of malignancy (b). Confocal microscopy of the dermo‐epidermal junction (approximately 3 mm x 2.5 mm field of view) displays densely packed and well‐defined, round to polycyclic, edged dermal papillae (c; arrows). At higher magnification (approximately 0.5 mm x 0.5 mm field‐of‐view), bright monomorphic cells aligned around dermal papillae are seen (arrow); the interpapillary spaces appear dark. The RCM findings are characteristic of a solar lentigo (d).

Figure 2

Clinical, dermoscopic, and RCM images of a lentigo maligna. The primary diagnosis after clinical/dermoscopic examination was solar lentigo with regression; however, lentigo maligna was in the differential diagnosis. On clinical examination, an irregularly shaped tan macule is seen in the left mandibular area (a). With dermoscopy, a tan pseudonetwork with focal dark‐brown angulated lines and streaks as well as an area with a few gray dots (arrow) can be seen (b). RCM of upper epidermal layers (approximately 1 mm x 1 mm field of view) shows loss of the regular epidermal architecture due to presence of large, bright, round and dendritic pagetoid cells (arrows) as well as sheets of dendrites (c; arrowhead). At the DEJ (approximately 1 mm x 1 mm field of view), there are bright dendrites (arrowhead) and tubular cell nests of various reflectivities (arrows) in irregularly shaped rete ridges with abrupt endings, also referred to as “medusa head‐like structures” or “irregular meshwork pattern” at the DEJ 28; outlines of single cells are occasionally observed within the nests. These RCM findings are consistent with lentigo maligna (d).