Langerhans Cell Histiocytosis Arising From a BCC: A Case Report and Review of the Literature

Langerhans cell histiocytosis (LCH) is a rare disease characterized by a proliferation of Langerhans cells. Several organs may be involved, including the skin, bone, and central nervous system. Adult onset of LCH and solely localized cutaneous involvement are quite uncommon. Langerhans cell histiocytosis has been found in combination with other skin lesions and systemic conditions, but no definitive conclusion exists for this phenomenon. We present a case report of a 63-year-old woman who initially presented with 3 pink papules on her forehead that had developed sequentially within 1 month, all diagnosed by biopsy as basal cell carcinoma (BCC) and appropriately treated. Concurrent with the appearance of the third BCC, the patient began developing crusted ulcerative nodules on her scalp. Biopsy of 1 scalp nodule revealed a BCC, but a repeat biopsy of the same nodule weeks later revealed LCH. Langerhans cell histiocytosis arising from a BCC is extremely rare. No absolute explanation exists regarding the transformation of a BCC into LCH, but understanding the behavior of Langerhans cells may give us better insight into how this process could occur.