title: Mediastinal masses diagnosed as thymus hyperplasia by fine needle aspiration cytology.
abstract: OBJECTIVE
  Thymic hyperplasia in the anterior mediastinum can occur in healthy children as idiopathic thymic hyperplasia or as a rebound effect after administration of chemotherapy in patients with malignancies. Thymic hyperplasia after chemotherapy is a well-documented phenomenon, particularly in children and less frequently in adults. Both forms of thymic hyperplasia are a diagnostic challenge, and most patients undergo surgical exploration. Fine needle aspiration cytology (FNAC) has supposed to be inadequate to diagnose benign thymic hyperplasia and to separate it from malignant disease.
  
  
  METHODS
  We report the cytologic findings on eight patients presenting with a mass in the anterior mediastinum that was diagnosed as thymic hyperplasia on FNAC. In five patients the masses developed after chemotherapy. The remaining three patients were healthy children. Three patients underwent ultrasound-guided aspiration; in five cases the procedure was performed under computerized guidance.
  
  
  RESULTS
  In all eight patients the cytologic smears showed a mixed population of lymphoid cells. Cytologic diagnosis of thymic hyperplasia was confirmed by immunophenotyping in three patients and by follow-up studies in all of them (median, 68 months; range, 8-113).
  
  
  CONCLUSIONS
  In contrast to previous reports, this study demonstrated the utility of FNAC as a front-line investigative procedure in diagnosing thymic hyperplasia.
authors.affiliation: Department of Medicine III, University of Ulm, Germany. markus.bangerter@medizin.uni-ulm.de
authors.forename: M
authors.initials: M
authors.lastname: Bangerter
authors.forename: W
authors.initials: W
authors.lastname: Behnisch
authors.forename: M
authors.initials: M
authors.lastname: Griesshammer
mesh_terms: D000293:Adolescent; D000328:Adult; D001707:Biopsy, Needle; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008477:Mediastinal Diseases / Q000175:diagnosis* / Q000473:pathology*; D013952:Thymus Hyperplasia / Q000175:diagnosis* / Q000473:pathology*