Solitary congenital self-healing reticulohistiocytosis in monozygotic twins.

We report monozygotic twins with congenital self-healing reticulohistiocytosis, whose lesions initially presented as hemorrhagic bullae at birth with rapid progression into crusted papules the following day. Physical examination disclosed crusted papules on the right side of the neck of twin 1 and a similar solitary lesion on the lateral side of the right thumb of twin 2. Excisional biopsy specimen findings of the neck and thumb lesions were consistent with Langerhans cell histiocytosis, which was further confirmed by positive CD1a staining. The lesions resolved completely by 2 months with no evidence of recurrence or systemic involvement. Congenital self-healing reticulohistiocytosis is a rare, self-limited form of Langerhans cell histiocytosis. Although familial clustering in Langerhans cell histiocytosis was previously reported, to the best of our knowledge there is no report suggesting familial clustering in congenital self-healing reticulohistiocytosis. Our patients are interesting in terms of raising the question of whether the presence of congenital self-healing reticulohistiocytosis in monozygotic twins is implicative of a genetic role in its pathogenesis.