A Unique Dermoscopy Pattern of Solitary Cutaneous Reticulohistiocytosis

Histiocytosis represents a group of rare disorders characterized by nonneoplastic proliferation of histiocytes and solitary cutaneous reticulohistiocytosis (SCR) is a form of non-Langerhans histiocytosis. SCR consists of small papule, usually single, varying in color from yellow to brownish-red, more frequent in young adults, and uncommon in childhood. We report a case of SCR in an 11-year-old child and emphasize a unique dermoscopy pattern of this lesion and its correlation with clinical and histopathological aspects in the diagnosis. 1. Introduction Initially described by Zak in 1959, solitary cutaneous reticulohistiocytosis (SCR) is a form of reticulohistiocytosis that is a rare presentation of non-Langerhans cell histiocytosis [1]. Despite being known since the 1950s its origin is still unknown. However, it is considered a nonneoplastic lesion, reactive, that originates by proliferation and differentiation of an anomalous histiocytic clone [2]. Still, regarding the etiology of the lesion, its development has already being related to traumatic areas, but the majority of cases appear spontaneously [3]. Recently, some authors have reviewed a high number of similar cases and proposed the name solitary epithelioid histiocytoma instead of the archaic “reticulohistiocytoma” [4]. It is more common in young adults and slightly more predominant in men [3]. The aim of this paper is to emphasize a unique dermoscopy pattern of this lesion and its correlation with clinical and histopathological aspects in the diagnosis. 2. Case Presentation An 11-year-old male was taken to a primary care because his mother noticed a lesion painful to touch on his neck that appeared 30 days previously; the lesion had been gradually growing. There was no history of obesity or dyslipidemia. The examination revealed a well-defined papule of firm consistency, 6.5？mm in diameter, erythematous, and nonexudative (Figures 1 and 2). There were no palpable lymph nodes or other systemic symptoms. Figure 1: Well defined papule of firm consistency on neck. Figure 2: Detail of the lesion: observe the nonexudative papule. Dermoscopy under nonpolarized light showed a well-defined central white-grayish area and white-pinkish streaks situated at the periphery, without dilated vessels (Figure 3). An excisional biopsy was done and the histopathologic study demonstrated a well-delimited lesion in the dermis that presented dilated venules and capillaries with erythrocytes inside: histiocytes with an eosinophilic cytoplasm of “glassy” appearance and vesiculosus nuclei. Also, lymphocytes were seen