LAUSR

Dear Editors, In vivo reflectance confocal microscopy (RCM) is a noninvasive technique that enables realtime imaging of superficial layers of the skin at a quasihistologic resolution. By means of RCM, the different skin structures can be visualized up to a depth of 300 μm, that usually encompasses the epidermis and superficial part of the dermis.1 Granulomatous diseases of the skin, such as cutaneous sarcoidosis, are characterized by the presence of an inflammatory infiltrate in dermis and hypodermis composed of histiocytes, multinucleated giant cells (MGC), and leukocytes adopting nodular, palisaded, or interstitial architecture.2 To our knowledge, cutaneous sarcoidosis features have never been characterized by means of RCM. A 55yearold man previously diagnosed with pulmonary sarcoidosis was referred due to the appearance of an asymptomatic lesion on his forehead 2 months ago. He presented an erythematous macule on clinical examination (Figure 1A). Polarized dermoscopy (DermLite DL4, 3Gen LLC, Dana Point, California, USA) revealed the presence of pseudonetwork and white rosettes (Figure 1B). Differential diagnoses included neoplasms like actinic keratosis and inflammatory conditions such as cutaneous sarcoidosis, subacute cutaneous lupus, and seborrheic dermatitis. A RCM examination was performed (Vivascope 1500, LucidTech, Inc; MAVIG GmbH), showing roundish structures in the papillary dermis corresponding to granulomas with MGC inside, characterized by a dark nuclei surrounded by a highly hyperrefractile cytoplasm (Figure 2A). A biopsy was performed. Histopathology revealed pale staining cell nodules occupying the superficial reticular dermis, located under the epidermis and in a periadnexal fashion. They were composed by circumscribed collections of epithelioid histiocytes, lacking central necrosis, and relatively devoid of lymphocytes. Only sparse