Laboratory studies used to define the extent of disease include the following: Complete blood count with differential Comprehensive metabolic panel Coagulation studies Early morning urinalysis Imaging studies include the following: Skeletal survey, including chest x-ray Ultrasonography of the abdomen MRI of the brain (to evaluate the pituitary gland) MRI of the spine MRI or CT of the skull (to look for temporal bone lesions) MRI or CT of the orbit (to look for facial bone lesions) CT of the chest (if the chest x-ray is abnormal) CT or MRI of the abdomen (if examination reveals hepatosplenomegaly or if liver function test results are abnormal) PET / CT if available (because it can identify bone lesions not seen on skeletal survey) Prognosis of Langerhans Cell Histiocytosis Generally, patients with single system disease (unifocal, multifocal, and central nervous system [CNS] risk lesions) and multisystem disease without risk organ involvement are considered low risk.