Spitz nevus and melanoma: evaluation with dermoscopy and reflectance confocal microscopy (2024)

Abstract

Keywords: melanoma, dermoscopy, reflectance confocal microscopy, Spitz nevus

Introduction

Spitz nevi (SN) include a wide range of benign nevi first described by Sophie Spitz in 1948 [1, 2]. SN are diagnostically ambiguous due to their clinical similarity to melanoma (MM). Dermoscopy has contributed significantly to improving the clinical diagnosis of pigmented and non-pigmented SN. More recently, reflectance Confocal Microscopy (RCM) has contributed substantially to improving a differential diagnosis between SN and melanoma [3]. SN occurs mainly in children and adolescents. MM is more frequent in the middle age and past the age of forty than among younger patients [1, 2, 4]. The dermoscopic patterns most commonly associated with SN are starburst, negative network, non-specific and hom*ogenous. Johr and Stolz described in total six dermoscopic patterns of SN. In addition to the four patterns mentioned above, they also included lesions with black pigment network and pink lesions [5–7].

In some cases, their presentation overlaps with the clinical features of malignant melanoma. The differential diagnosis of such lesions can be challenging. However, histopathological evaluation of SN reveals distinct patterns of genetic aberrations compared to melanoma and common nevi [7–9].

Many attempts have been made to determine dermoscopic diagnostic criteria of SN [10, 11]. RCM is a promising and useful tool in differentiating SN from MM and other melanocytic proliferations.

A non-invasive approach could open the possibility of a more precise pre-histological diagnosis with the reduction of surgical excision of SN.

Aim

This study aimed to describe dermoscopic and RCM features of SN compared to MM and assess the RCM usefulness in the final differential diagnosis.

Material and methods

A retrospective study including 26 melanocytic lesions was performed in three dermatologic centres (Private Dermatology Clinic in Tychy, Poland, between January 2016 and December 2020, Department of Dermatology at the University of Trieste, Italy from October 2017 to January 2020 and Military Institute of Medicine in Warsaw, Department of Dermatology, between January 2018 and January 2020).

Patients with a histopathological diagnosis of SN and MM who underwent RCM and dermoscopic evaluation were included in the study. Four SN regarding children under 12 years old were clearly benign in dermoscopy, with no biopsy, since the lesions were stable clinically and dermoscopically.

All images were analysed by certified dermatologists. The dermoscopic diagnosis was performed using standard terminology to qualify four dermoscopic patterns of SN: starburst, negative network, and hom*ogenous or non-specific pattern. Dermoscopic images were analysed by A.P.A., C.C., and E.F. Confocal imaging was performed with a reflectance confocal microscope in vivo (Vivascope1500; Lucid Inc., Rochester, NY, USA). For each lesion, a minimum of three mosaics were available for re-evaluation: one at the level of the superficial epidermis (stratum granulosum/spinosum), one at the level of the dermo-epidermal junction (DEJ), and one from the upper dermis.

RCM features assessed at the epidermis level and DEJ are reported in Table 1. The RCM examinations blinded to histology have been re-evaluated by two experts (A.P.A. and M.S.).

The study was conducted in compliance with the Declaration of Helsinki. For each evaluation, written informed consent was obtained.

Results

Discussion

SN are benign melanocytic lesions mostly identified by characteristic clinical and dermoscopic features. Although histopathological and dermoscopic criteria of SN have been considerably described, differential diagnosis of SN and MM is challenging [12–14]. In our study, most SN and MM in dermoscopy presented a “starburst” type of architecture (Figure 4 A). Dermoscopic features differed between MM and SN, with six of them reaching statistical significance. In symmetric and well-demarcated cases, differential diagnosis with melanoma is easier. The difficulties may occur in lesions with non-specific dermoscopic patterns [15–18]. Especially when blue colour within the lesion is observed. Pellacani et al. [19] described the most common features of SN in RCM. There were cut-off, dense junctional, and plump, bright cell nests. A broadened honeycomb pattern of the epidermis, disarranged epidermal pattern, and the presence of small pagetoid cells were more likely correlated with a melanoma diagnosis. Non-edged papillae were significant for MM diagnosis, while dense junctional nests were more common in SN [12, 18]. Previous studies showed different RCM epidermal features between MM and SN; a correlation between striking cells pleomorphism and melanoma was found [20]. Carrera and Marghoob [21] highlighted the importance of the distribution of epidermal pagetoid cells within SN. In SN, pagetoid cells are rare, distributed in the suprabasal layers, and mostly clustered toward the lesion centre. In melanoma, pagetoid cells are located randomly in a rather diffuse manner. However, both MM and SN can manifest architectural disarray and cytologic atypia. In our study, there were significant differences in the architecture of the epidermis between melanoma and Spitz nevi. MM showed an atypical honeycomb pattern, while most SN revealed typical epidermal architecture. The DEJ also showed significant differences between MM and SN. Most SN revealed a meshwork pattern, whereas melanoma had an atypical meshwork pattern. Cerebriform nests and sheet-like structures proved to be essential diagnostic features as they may have a significant role in melanoma recognition. It is worth mentioning that no study to date has shown the relevance of sheet-like structure presence in the differential diagnosis between MM and SN in RCM. This significant feature presents as clusters of atypical cells in the histopathological evaluation.

Conclusions

A combined approach using dermoscopy and RCM improves the differential diagnosis of SN and MM. The main limitation of our study was a small group of patients. Although our study showed some significant differences between SN and MM in RCM, further research on a larger group should be considered.

Acknowledgments

Research was conducted in EsteDerm, Private Dermatology Clinic, Aleja Bielska 135b/17, Tychy, Poland.

Conflict of interest

The authors declare no conflict of interest.

References