Solitary congenital self-healing reticulohistiocytosis.

Congenital self-healing reticulohistiocytosis (CSHR) was first described in 1973 by Hashimoto and Pritzker. Since then, both multiple and solitary forms have been described. We report a further case of solitary congenital self-healing reticulohistiocytosis. CSHR is a rare disorder which frequently presents a diagnostic dilemma in the newborn. Nodular forms of systemic Langerhans cell histiocytosis may present in a manner similar to CSHR. Because their differentiation on histopathological grounds is impossible, physical examination, laboratory investigations, and follow-up are necessary to ensure a lack of systemic involvement. Although previously thought to represent a rare variant of CSHR, solitary lesions of CSHR account for almost 25% of reported cases. A review of the literature relating to solitary CSHR, and a consideration of the differential diagnosis of a solitary congenital nodule, are also presented.