title: Atypical squamous cells as a diagnostic pitfall in pulmonary Wegener's granulomatosis. A case report.
abstract: BACKGROUND
  Wegener's granulomatosis (WG) is characterized by systemic, necrotizing, granulomatous inflammation accompanied by vasculitis. It classically involves the triad of the upper respiratory tract, lungs and kidneys. Isolated pulmonary lesions of WG may present in some patients as pulmonary masses, simulating neoplasms. The features of WG can be suggested by cytologic study. Atypical epithelial cells associated with WG have previously been reported as a cause of a false positive diagnosis of bronchoalveolar carcinoma.
  
  
  METHODS
  In this case the cytologic findings included atypical squamous cells in a background of acute, chronic and granulomatous inflammation. In several respiratory specimens the atypical squamous cells were incorrectly interpreted as diagnostic of squamous cell carcinoma. The correct diagnosis of WG was confirmed with open lung biopsy, which demonstrated necrotizing granulomatous inflammation with geographic necrosis and associated vasculitis.
  
  
  CONCLUSIONS
  Markedly atypical squamous cells mimicking squamous cell carcinoma can be found accompanying the inflammatory process associated with WG and are a possible diagnostic pitfall. The possibility of WG as well as other inflammatory processes should always be considered in the differential diagnosis of squamous cell carcinoma of the lung. This case is the only reported case of WG in which atypical squamous cells were a diagnostic pitfall, initially suggesting a diagnosis of squamous cell carcinoma.
authors.affiliation: Department of Pathology, Norton Suburban Hospital, 4001 Dutchman's Lane, Louisville, Kentucky 40207, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Williamson
authors.forename: Sidney S
authors.initials: SS
authors.lastname: Murphree
authors.forename: Lisa
authors.initials: L
authors.lastname: Wills-Frank
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005260:Female; D014890:Granulomatosis with Polyangiitis / Q000473:pathology*; D006801:Humans; D008168:Lung / Q000473:pathology