Bone Langerhans cell histiocytosis with pulmonary involvement in an adult non-smoker: A case report and brief review of the literature.

Langerhans cell histiocytosis (LCH) is a rare disease of unknown cause, which encompasses a set of disorders of multiple organs with various clinical presentations that share the common characteristic of sizeable Langerhans cell infiltration. The clinical spectrum of LCH ranges from solitary bone lesions to involvement of other organs. lung involvement in LCH may be part of a multisystem disease, which almost exclusively occurs in adult smokers, while it is overlooked or misdiagnosed in the majority of non-smokers. High-resolution computed tomography (HRCT) of the chest is crucial for diagnosis; however, the treatment and prognosis of this disease have not been clearly determined. We herein present the case of a non-smoking adult patient who presented with lower limb pain and was diagnosed via biopsy with lch with multisystem involvement, including the bone and lungs. Lytic lesions in the corpus of the sacroiliac joint, sacrum, acetabulum and femoral head by a soft tissue mass were observed on diagnostic CT. In addition, chest HRCT revealed multiple cysts in the bilateral lungs, predominantly in the upper lobes. The final diagnosis of LCH was confirmed by histopathological examination and immunohistochemical staining for CD1a and S-100. Corticosteroid treatment alleviated lower limb pain and improved the patient's quality of life; thus, corticosteroids may be considered as a potential treatment option for patients with LCH.