title: Keratinized squamous cells in fine needle aspiration of the brain. Cytopathologic correlates and differential diagnosis.
abstract: OBJECTIVE
  To analyze the differential diagnosis when keratinized squamous cells are found in a brain aspirate.
  
  
  METHODS
  Twenty cases of brain aspirates with keratinized squamous cells were retrieved (1982-2001). Diagnoses included craniopharyngioma (CP) (n = 11), metastatic squamous cell carcinoma (SCC) (n = 5), epidermoid cyst (EC) (n = 3) and Rathke cleft cyst (RCC) (n = 1). Aspirates were obtained under stereotactic radiologic (CT) guidance. Smears were stained with Diff-Quik or Papanicolaou stain, and cell block sections were stained with hematoxylin and eosin. Radiologic and histopathologic correlation with subsequent resection specimens was performed in selected cases.
  
  
  RESULTS
  CP showed cellular smears with numerous keratinized squamous cells in a background of degenerated cellular and keratinaceous debris. Also noted were clusters of anucleate squamous cells, multinucleated giant cells, histiocytes, calcified debris and characteristic fragments of basaloid epithelial cells. Metastatic SCC showed single cells and tissue fragments of markedly atypical and focally keratinized cells with enlarged, hyperchromatic nuclei; prominent pleomorphism in a background of necrotic cellular debris and acute inflammatory exudate. EC showed numerous isolated keratinized squamous cells often with prominent keratohyaline granules and occasional parakeratotic cells in a relatively clean background. RCC showed single cells and aggregates of benign-appearing squamous cells admixed with numerous anucleate squames and hemosiderin-laden macrophages. Glandular-type epithelium was present only rarely.
  
  
  CONCLUSIONS
  Squamous cell-containing lesions in the brain present a spectrum of pathologic entities. Although they all display the common morphologic denominator of keratinizing squamous cells, subtle cytomorphologic differences exist in these lesions, permitting an accurate cytopathologic diagnosis. Clinicardiologic features and anatomic location of the tumor in the brain are additionally helpful.
authors.affiliation: Departments of Pathology and Neurosurgery, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, Maryland 21287, USA.
authors.forename: Anil V
authors.initials: AV
authors.lastname: Parwani
authors.forename: David C
authors.initials: DC
authors.lastname: Taylor
authors.forename: Peter C
authors.initials: PC
authors.lastname: Burger
authors.forename: Yener S
authors.initials: YS
authors.lastname: Erozan
authors.forename: Alessandro
authors.initials: A
authors.lastname: Olivi
authors.forename: Syed Z
authors.initials: SZ
authors.lastname: Ali
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D001932:Brain Neoplasms / Q000737:chemistry / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000737:chemistry / Q000473:pathology*; D020863:Central Nervous System Cysts / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003397:Craniopharyngioma / Q000473:pathology; D003937:Diagnosis, Differential; D004814:Epidermal Cyst / Q000473:pathology; D005260:Female; D006801:Humans; D007633:Keratins / Q000032:analysis*; D008297:Male; D008875:Middle Aged
chemical_list: D007633:Keratins