Cutaneous involvement in Rosai–Dorfman disease: clinical and dermoscopic features

Abstract

Rosai–Dorfman disease (RDD) is a rare non-Langerhans cell histiocytosis. RDD usually presents with massive, painless, bilateral cervical lymphadenopathy, with or without systemic symptoms. Although the skin represents the most common extranodal site, clinical and dermoscopic features of cutaneous involvement in RDD (CRDD) remain insufficiently described, based mainly on single observations.1, 2 A better understanding of CRDD is required to avoid diagnostic delays and unnecessary investigations. This series aimed to describe the clinical, dermoscopic, and therapeutic features of CRDD. Records of all patients diagnosed with cutaneous histiocytosis from 2016 to 2024 at the Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia, were retrieved. Only patients with histopathologically confirmed CRDD were included. Two dermatologists (NL and RT) independently evaluated dermoscopic images. Nine cases of CRDD were identified. Clinical, histopathological, and therapeutic data are detailed in Table 1 (available via Mendeley https://doi.org/10.17632/krxz2jkyn3.1). The mean age was 55 (37–66), with a slight male predominance (sex ratio 0.66). Patients had infiltrated plaques and nodules, often showing yellowish or brick-red color, and telangiectasia, frequently located in the head and neck region (5/9). Four patients had enlarged lymph nodes (4/9), which frequently involved the neck and axillae. Three patients had ocular manifestations, all involving the anterior segment: two had ocular redness with neovascularization and one had episcleritis. The liver and central nervous system were less commonly involved. Dermoscopy was performed in seven patients, revealing yellow clods (n = 3), homogeneous yellow backgrounds (n = 2), linear and/or serpentine vessels (n = 3), yellow-brown structureless areas (n = 3), pigment network (n = 2), and red-purple background (Figure 1). Interestingly, dermoscopy of the conjunctiva showed yellow clods or structureless areas in two patients (Figure 1). Histological examination confirmed the diagnosis of RDD in all cases. Emperipolesis was noted in six cases. In three patients, several biopsies were needed to confirm the diagnosis, with initial biopsies showing dense lymphocytic infiltrate that hindered histiocytic proliferation. Several treatment options were employed, with systemic corticosteroids being the most common approach, leading to partial regression of lesions. Observation was indicated in two patients who experienced remarkable remission of their disease. This series, the largest describing CRDD in North Africa, highlighted characteristic features of the disease. Cutaneous manifestations are non-specific, with asymptomatic red-brown to yellow papules, nodules, or plaques of varying sizes that can be confined or disseminated. Lesions are commonly located in the head and neck region.3 However, all anatomic sites could be affected. The primary differential diagnoses are lymphomas and pseudolymphomas. Dermoscopy helps point toward the correct diagnosis. Dermoscopic features of CRDD include reddish-brown, red-orange, or yellowish background with yellowish or orange clods or structureless areas. Yellow and orange structures correlate with dense dermal infiltrate of histiocytes.1 Linear irregular vessels are common and are correlated with rich vascularization. These aspects are distinct from those of lymphomas that typically reveal a salmon-red background with white and orange structures.4 This series also highlights the importance of the dermoscopy of the conjunctiva, which could reveal signs of RDD. However, dermoscopic features of CRDD are not specific, differentials include sebaceous tumors and xanthomatous lesions that may show similar features. Histopathological diagnosis is based on the identification of large histiocytes, typically S100, CD68-positive, and CD1a-negative, with emperipolesis. However, dense lymphocytic infiltrate may hinder histiocytic proliferation, falsely suggesting the diagnosis of pseudolymphoma. Therefore, keeping high suspicion of the disease based on characteristic clinical and dermoscopic features of CRDD is paramount. CRDD is a self-limited disorder that is often managed conservatively. For severe cases of extracutaneous involvement, corticosteroids are the first-line therapy.5 In refractory cases, immunosuppressants or monoclonal antibodies may be considered. We thank Drs. Fatma Ghezail and Meriem Tabka for their contribution to the data collection. Informed consent was obtained from all patients included in this study. Clinical, histopathological, and therapeutic data are available via Mendeley https://doi.org/10.17632/krxz2jkyn3.1. Additional data can be made available upon reasonable request from the corresponding author.