LAUSR

To the Editor, Rosai-Dorfman disease, or Sinus histiocytosis with massive lymphadenopathy, described by Rosai and Dorfmann in 1969,1 is mostly a benign idiopathic histiocytic proliferation, that commonly affects the cervical lymph nodes, but can also involve other nodal sites and any organs of the body. However, the extranodal involvement is purely cutaneous. The cutaneous Rosai-Dorfman disease (CRD), without nodal and visceral involvement, is extremely rare, and a few such cases have been reported.2-10 The use of dermoscopy and reflectance confocal microscopy to asses CRD have not yet been reported. The histological examination revealed dense and diffuse, or nodular inflammatory infiltrates, composed of neutrophils, plasma cells, lymphocytes, and histiocytes in the dermis. The histiocytes engulfed the inflammatory cells, within their cytoplasm, through a process known as emperipolesis.2 Immunohistochemistry showed that the large histiocytes, with abundant cytoplasm, were positive for S-100 and CD68 proteins, and negative for the CD1a protein.3,4 Herein, we report a case of generalized pure cutaneous Rosai-Dorfman disease and its dermoscopic and reflectance confocal microscopic features. A 53-year-old man presented with a 4-month history of numerous, asymptomatic, dome-shaped, firm papules, and nodules on the face, neck, trunk, and extremities (Figure 1A-D). These were 1-8 mm in diameter, red-brownish in color, and had smooth shiny surfaces. The patient never complained of fever, cough, weight loss, or fatigue. The examination failed to show any superficial lymphadenopathy; however, a superficial lymph node ultrasound showed an increase in left inguinal lymph nodes, and the result of the ultrasound-guided superficial lymph node fine-needle aspiration biopsy was normal. Routine laboratory and serological tests, for Epstein-Barr virus or cytomegalovirus titers, were normal. The chest and abdominal computed tomography (CT), the brain magnetic resonance, and the bone marrow examination were negative. Notably, the indicators of the tumor necrosis factor alpha (11.50 pg/mL) and interleukin-6 (12.90 pg/mL) were elevated, suggesting that treatment with a biological agent may be effective.