<s>[INST] <<SYS>> This is a medical question of type : exams and tests <</SYS>> How to diagnose Langerhans cell histiocytosis ? [/INST] How is Langerhans cell histiocytosis diagnosed? Testing for Langerhans cell histiocytosis (LCH) may include bronchoscopy with biopsy, x-ray, skin biopsy, bone marrow biopsy, complete blood count, and pulmonary function tests. Because LCH is sometimes associated with cancer, CT scans and a biopsy may be done to rule out possible cancer. Additional information about the diagnosis of LCH can be viewed on the Histiocytosis Association's website. </s>