Congenital self-healing histiocytosis. Report of two cases with histochemical and ultrastructural studies.

Congenital self-healing histiocytosis (CSHH) is a rare primary skin disorder. Of the two cases in newborn infants reported here, one had numerous widespread lesions while the other had a solitary ulcerating scalp nodule. Both neonates were otherwise healthy; neither exhibited either systemic involvement or involvement of mucous membranes. The findings drawn from the skin biopsies, including histology, S-100 positivity in the majority of the cells, and the presence of Birbeck granules, were indistinguishable from those described in infantile Letterer-Siwe disease (histiocytosis X). However, the benign clinical course, with rapid regression of the nodules in both cases, was diagnostic of CSHH.