title: Abnormal fluorodeoxyglucose PET in pulmonary Langerhans cell histiocytosis.
abstract: BACKGROUND
  Pulmonary Langerhans cell histiocytosis (PLCH) is an inflammatory lung disease strongly associated with cigarette smoking and an increased risk of malignant neoplasms. Although the chest CT scan characteristics of PLCH are well recognized, the PET scan characteristics of adults with PLCH are unknown.
  
  
  METHODS
  We identified 11 patients with PLCH who underwent PET scanning over a 6-year period from July 2001 to June 2007. The presenting clinicoradiologic features including PET scan and chest CT scan findings were analyzed.
  
  
  RESULTS
  Five of 11 patients had positive PET scan findings. Of the five PET scan-positive patients, 4 (80%) were women, 4 (80%) were current smokers, and the median age was 45 years (age range, 31 to 52 years). PET scan-positive findings were more likely to be present if the scan was performed early in the clinical course. Three PET scan-positive patients (60%) had multiorgan involvement. PET scan-positive patients had predominantly nodular inflammatory lung disease (> 100 nodules) with most nodules measuring < 8 mm, whereas all PET scan-negative patients had predominantly cystic lung disease with fewer nodules (< 25 nodules). Notable abnormal PET scan findings included foci of increased uptake in nodular lung lesions, thick-walled cysts, bone, and liver lesions. The mean maximum standardized uptake value of the PET scan-positive lesions ranged from 2.0 to 18.2.
  
  
  CONCLUSIONS
  PLCH may be associated with abnormal thoracic and extrathoracic PET scan results. Patients with nodular disease seen on chest CT scans appear more likely to have abnormal PET scan findings. Our results suggest that PET scan imaging cannot reliably distinguish between the benign inflammatory nodular lesions of PLCH and malignant lesions.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Krajicek
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Jay H
authors.initials: JH
authors.lastname: Ryu
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hartman
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN.
authors.forename: Val J
authors.initials: VJ
authors.lastname: Lowe
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN. Electronic address: vassallo.robert@mayo.edu.
authors.forename: Robert
authors.initials: R
authors.lastname: Vassallo
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D006646:Histiocytosis, Langerhans-Cell / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011336:Probability; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D019788:Fluorodeoxyglucose F18