Nose, Epithelium - Hyperplasia, Atypical
comment:Atypical hyperplasia ( Figure 1 , Figure 2 , Figure 3 , Figure 4 , and Figure 5 ) is a focal or multifocal hyperplastic change (i.e., increased numbers of cells) with features of cellular atypia, which suggests a more aggressive behavior. "Cellular atypia" refers to the presence of morphologic features that are consistent with altered differentiation (cellular pleomorphism, anaplasia) or growth (disorganization of cells, dyskeratosis, abnormal mitotic figures). Atypical hyperplasia can occur in any of the epithelial cell types found in the nasal cavity or in the glands (septal, Bowman's, or Steno's glands) but is most commonly seen in the transitional or respiratory epithelium. Atypical hyperplasia of the olfactory epithelium often manifests as proliferation of basal epithelial cells that extends below the basement membrane. Atypical hyperplasia is thought to represent a preneoplastic change.
recommendation:Atypical hyperplasia is an important finding that should be diagnosed whenever present and assigned a severity grade. When atypia occurs within a metaplastic lesion, the metaplasia should be diagnosed, but the modifier "atypical" should be added to the diagnosis (e.g., Nose, Olfactory epithelium - Metaplasia, Respiratory, Atypical). The type of epithelium affected should be included in the diagnosis as a site modifier (i.e., squamous, transitional, respiratory, or olfactory epithelium).
related links:Nose, Epithelium - Hyperplasia
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