Dermoscopy of Early-Stage Mycosis Fungoides: Comparative Study with Inflammatory Dermatoses

The diagnosis of early-stage mycosis fungoides (MF) is challenging and may be confused with plaque psoriasis (PP) and chronic dermatitis (CD).

Our study aimed to describe the dermoscopic features of early-stage MF and compare them with PP and CD.

This was a multicenter cross-sectional study conducted in three tertiary referral dermatology departments in Tunisia between January 2021 and December 2021, including 89 patients with phototype III-V. For all patients, up to three representative cutaneous lesions were selected and examined using dermoscopy. Both clinical and dermoscopic photos were recorded for each selected lesion. Dermoscopic photos were interpreted by two independent evaluators.

Vascular structures significantly associated with the diagnosis of early-stage MF included polymorphic, coiled, serpentine, and linear vessels, in an unspecific distribution. Perpendicular white lines, white circles, and spermatozoa-like vessels were only noted in MF. Branched vessels were only observed in granulomatous MF. Conversely, monomorphous vessels in uniform distribution were associated with PP, whereas CD was associated with monomorphous vessels with unspecific distribution. Non-vascular structures associated with the diagnosis of MF included reticular lines, orange background color, and structureless areas. Pink background was more prevalent in PP and CD. Additionally, yellow clods were more frequently observed in patients with CD.

This study highlights the characteristic dermoscopic features of early-stage MF compared with PP and CD. Perpendicular white lines, white circles, and spermatozoa-like vessels were only seen in MF. Follicular plugs and clods were features of folliculotropic MF and can help guide skin biopsy sites in difficult cases.