Unifocal scalp langerhans cell histiocytosis in an adolescent child: A case report

Langerhans cell histiocytosis (LCH) is a rare neoplasm of myeloid dendritic cells that often presents diagnostic challenges due to its variable clinical manifestations. It is most commonly seen in the first three years of life. LCH with isolated scalp involvement in children, particularly adolescents, remains underreported. We report a case of a 12-year-old boy who presented with a painless swelling on the left frontal scalp. Imaging revealed a lytic bone lesion in the frontal bone. Fine needle aspiration cytology of the mass suggested a benign histiocytic lesion consistent with Langerhans cell histiocytosis. The mass was completely excised, and subsequent histopathologic examination confirmed the diagnosis of LCH. Immunohistochemistry showed that the neoplastic cells were diffusely positive for Langerin and CD1a, further supporting the diagnosis. LCH should be considered as a differential diagnosis in children presenting with a lytic scalp mass. Histopathology combined with immunohistochemistry is crucial for definitive diagnosis. • LCH is mostly seen in the first three years of life with an annual incidence rate of 5 - 9 new cases per 1 million population (below 2 years) • HL is rare in adolescents and adults • Isolated LCH has an excellent outcome if diagnosed early. • Radiologic imaging along with fine needle aspiration cytology, histopathology and immunohistochemistry are crucial in diagnosing LCH