The Differential Diagnosis of Hypopigmented Mycosis Fungoides and Vitiligo With Reflectance Confocal Microscopy: A Preliminary Study

Abstract

Objective: To investigate the role of reflectance confocal microscopy (RCM) in the differential diagnosis of hypopigmented mycosis fungoides (HMF) and vitiligo. Methods: Cases with persistent hypopigmented patches, suspicious of early stage vitiligo, or HMF were imaged with RCM. The melanin contents and inflammatory conditions of the epidermis and superficial dermis of the lesions were compared with the same layers of the adjacent skin, and then, the imaged lesions were biopsied and analyzed by histology. Results: 15 cases were enrolled in this study, and based on the RCM findings, there was just slight or moderate reduction of melanin but no melanin absence in the basal cell layer of HMF lesions. The finding of monomorphous weakly refractile, oval to round cells on the basis of vesicle-like dark space was clearly elucidated in the epidermis of the lesions by RCM, which indicates the Pautrier's microabscesses on histopathology. Among those 15 cases, 13 cases were identified as HMF, and the other two cases were vitiligo, based on RCM findings, which were confirmed by histology analysis. Conclusions: The RCM findings correlated well with histology results in the screening of HMF, which indicates the RCM is an important tool in the early detection and differential diagnosis of HMF.

Keywords: detection; differential daignosis; hypo-pigmented mycosis fungoides; imaging; reflectance confocal microscopy (RCM); vitiligo.

Figure 1

The clinical image of three cases of HMF. An 18-year old woman with the hypopigmented patches for 2 years on arms (a) and legs, and a 25-year-old (b) and 19-year-old man (c), with generalized lesions on bodies and limbs. The hypopigmentary patches were 2–5 cm in diameter, slightly scaly, with no infiltration (arrows).

Figure 2

The honeycomb pattern of stratum spinosum (a), the normal basal cell layer, the dermal-epidermal junction of vitiligo (c) and the histology of vitiligo. There was no inflammation in the regular arranged honeycomb pattern of stratum spinosum (a). There was no melanin reduction in the basal cell layer of normal DEJ (b). The significant reduction or melanin absence (circles) in the basal cell layer of DEJ of vitiligo (c). There is no melanin in basal cell layer of vitiligo (d).

Figure 3

The RCM image of HMF (a,b), the histology of HMF (c) and immunochemistry-stained image of HMF (d). The monomorphous weakly refractile, oval-to-round cells (a,b, arrows) on the basis of vesicle-like dark spaces were clearly elucidated in epidermis of the lesions by RCM, which indicates the Pautrier's microabscesses on histopathology (c). Immunohistochemical analysis (d) demonstrated the HMF was characterized by CD8+ T cells residing predominantly in the dermal papillae.