Langerhans cell histiocytosis presenting as folliculitis decalvans and intertrigo

Langerhans cell histiocytosis is a rare disease of unknown etiology characterized by a proliferation of histiocytic cells in various tissues. A few years ago, it was discovered that a large proportion of LCH cells carry a BRAF mutation, making a neoplastic genesis conceivable. Since multiple organs can be affected by the proliferating cells, the symptoms of Langerhans cell histiocytosis are diverse. The most commonly affected organ in adult Langerhans cell histiocytosis is the lung, followed by bones. In one third of cases, the skin is affected, giving the dermatologist a particularly important role in diagnosis.

Characteristic findings include the triad of erosive, eczema-like skin changes on the scalp and in the intertriginous areas combined with diabetes insipidus. The diagnosis is ultimately made histologically. Typical findings are dense infiltrates consisting of large cells with bean-shaped nuclei, characterized immunohistochemically by detection of CD1a antigen on the cell surface.

Therapeutically, in addition to topical steroids, PUVA, systemic immunosuppressants, polychemotherapy regimens as well as surgical and radiotherapeutic measures are applied. Based on the latest findings regarding the existing BRAF mutation, the use of BRAF inhibitors is currently being discussed.