title: Diagnostic pitfalls in fine needle aspiration cytology of atypical apocrine metaplasia in a breast lesion. A case report.
abstract: BACKGROUND
  Apocrine metaplastic cells are frequently encountered in fine needle aspirates of breast lesions. Atypical apocrine metaplastic cells with signet ring features can also occur, and their presence may present a diagnostic dilemma in the differentiation of benign versus malignant lesions.
  
  
  METHODS
  A fine needle aspirate of a 2.5 x 1.0-cm, subareolar mass in a 47-year-old female showed atypical cells with signet ring morphology. Also present were clusters of cells that were enlarged and showed nuclear atypia, prominent nucleoli and cytoplasmic granules. Papillary cohesive clusters of ductal cells were also identified. The fine needle aspiration diagnosis was mucinous carcinoma. The nodule was excised, and the histologic diagnosis was sclerosing ductal papilloma with atypical apocrine metaplasia.
  
  
  CONCLUSIONS
  Atypical apocrine cells can be misinterpreted as mucinous carcinoma or usual duct adenocarcinoma on fine needle aspiration cytology. We present clues that may help in rendering the correct interpretation.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Department of Pathology, M. D. Anderson Cancer Center, Houston, Texas, USA. deepali.gupta@uth.tmc.edu
authors.forename: Deepali
authors.initials: D
authors.lastname: Gupta
authors.forename: James A
authors.initials: JA
authors.lastname: Wolf
authors.forename: Illana A
authors.initials: IA
authors.lastname: Rubenchik
authors.forename: Lavinia P
authors.initials: LP
authors.lastname: Middleton
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000473:pathology*; D001050:Apocrine Glands / Q000473:pathology*; D001707:Biopsy, Needle; D001943:Breast Neoplasms / Q000473:pathology*; D002466:Cell Nucleolus / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008679:Metaplasia / Q000473:pathology*; D008875:Middle Aged; D010212:Papilloma / Q000473:pathology