Crohn's disease and lichen nitidus: a case report and comparison of common histopathologic features.

We describe a 54-year-old black woman with Crohn's disease, who developed lichen nitidus, the third report of a patient with both diseases. The rarity of these diseases individually and the histopathologic features in common imply that the two diseases are linked. Multinucleated giant cells, a common finding in the lesions of Crohn's disease, are less common in the lesions of lichen nitidus. The presence of multinucleated giant cells in lichen nitidus in all three case reports is distinctly unusual. The infiltrates of Crohn's disease and lichen nitidus contain CD-68-positive macrophages. As such, the subset of lichen nitidus with giant cells should be recognized as a cutaneous manifestation of Crohn's disease.