Reflectance confocal microscopy features of mycosis fungoides and Sézary syndrome: correlation with histopathologic and T-cell receptor rearrangement studies

Abstract

Background: Mycosis fungoides/Sézary syndrome (MF/SS) often requires multiple skin biopsies for definitive diagnosis. In vivo reflectance confocal microscopy (RCM) visualizes high-resolution cellular detail of the skin. The objective of this study is to evaluate the morphologic features of MF/SS using RCM and to correlate RCM features with histopathology and T-cell receptor (TCR) gene rearrangement studies.

Methods: A cohort of patients with active/recurrent or suspicious MF/SS disease was prospectively recruited for RCM imaging and histopathologic/RCM images were evaluated. Statistical analyses were performed to identify unique RCM features and to correlate RCM features with histopathologic findings and TCR rearrangement studies.

Results: Eighty-three lesions were evaluated. Correlation between RCM and histopathology was moderate for all relatable features (κ = 0.41, p<0.001), almost perfect for intraepidermal atypical lymphocytes [prevalence and bias-adjusted kappa (PABAK) = 0.90], and fair for Pautrier collections (κ = 0.32, p = 0.03). Lesions with Pautrier collections identified by RCM were significantly more likely to show TCR clonality (p = 0.04) and diagnostic features of MF/SS on histopathology (p = 0.03).

Conclusions: Our study captures morphologic RCM criteria for a variety of skin lesions. Pautrier collections visualized by RCM are associated with improved histopathologic diagnosis and detection of TCR gene clonality. Although further studies are needed to validate the diagnostic implications of RCM for MF/SS, our study highlights the potential utility of RCM.

Keywords: RCM; mycosis fungoides.

Fig. 1

Study design and participants. Forty-one patients were included in the study. Nineteen participants were recently diagnosed mycosis fungoides/Sézary syndrome (MF/SS) patients with biopsy-proven active disease and 22 participants had suspicious MF/SS disease or disease recurrence. Among patients with suspicious MF/SS disease or disease recurrence, 29 biopsies were performed after reflectance confocal microscopy evaluation.

Fig. 2

Clinical images of mycosis fungoides/Sézary syndrome lesions used for reflectance confocal microscopy. (A) Erythematous patch, (B) hypopigmented patch, (C) plaque, (D) hyperpigmented patches, (E) papules, (F) erythroderma, (G) diffuse erythroderma, (H) perifollicular papules and (I) poikiloderma.

Fig. 3

Histopathology and reflectance confocal microscopy (RCM) images of plaque lesions. (A) Atypical lymphocytes infiltrating the epidermis [hematoxylin & eosin (H&E) stain, original magnification ×100]. (B) RCM image showing brightly reflective cells (arrows) scattered in the stratum spinosum with focal areas of epidermal disarray (asterisk, *) (scale bar = 100 μm). (C) Collections of atypical lymphocytes forming Pautrier collections within epidermis (H&E, ×100). (D) RCM image showing well-demarcated, vesicle-like, dark spaces containing weakly reflective cells (arrows) (scale bar = 100 μm).

Fig. 4

Histopathology and reflectance confocal microscopy (RCM) images of patch lesions. (A) Perivascular infiltration by atypical lymphocytes (H&E, ×50). (B) RCM image showing weakly reflective cells surrounding dilated canalicular structures in the papillary dermis (arrowheads) (scale bar = 100 μm). (C) HP showing fibrosis of upper papillary dermis (H&E, ×100). (D) RCM image showing disorganized distribution of reflective bundles (arrows) with scattered brightly reflective cells in the papillary dermis (scale bar = 100 μm).

Fig. 5

Histopathology and reflectance confocal microscopy (RCM) images of tumor lesions. (A) Langerhans cells in the epidermis (arrow) (CD4 immunohistochemical stain, ×200). (B) RCM image showing brightly reflective, dendritic cells with spinous processes (arrows) in the stratum spinosum (scale bar = 100 μm).

Fig. 6

Histopathology and reflectance confocal microscopy (RCM) images of folliculotropic mycosis fungoides. (A) HP highlighting features of atypical lymphocytes surrounding and infiltrating hair follicles (H&E, ×50). (B) RCM image showing weakly reflective cells (arrowheads) surrounding and infiltrating follicular epithelium (scale bar = 100 μm). (C) RCM image showing weakly reflective cells (arrowheads) infiltrating follicular epithelium (scale bar = 100 μm). (D) RCM image showing mucinous deposition (arrows) appearing as hypo-reflective space surrounding follicular epithelium (scale bar = 100 μm).