Premalignant / preinvasive lesions
Atypical immature metaplasia

Topic Completed: 1 October 2013

Revised: 25 September 2019

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Atypical immature metaplasia [title]

Seema Khutti, M.D.
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Cite this page: Khutti S. Atypical immature metaplasia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cervixatypicalimmaturemetaplasia.html. Accessed December 5th, 2019.
Definition / general
  • First described by Crum et al (Cancer 1983;51:2214) as a low grade lesion but now often includes both high grade and low grade lesions
  • Currently is a poorly reproducible diagnosis which lacks a uniform definition; spans a morphologic spectrum and includes many diagnostically challenging cases with an immature appearance
  • HPV+ cases are associated with future diagnosis of HSIL
  • Squamous proliferation of transformation zone and endocervical glands associated with abnormal Pap smears and a colposcopically visible abnormality
  • Based on size and distribution of lesion
Microscopic (histologic) description
  • More cellular than usual immature squamous metaplasia
  • Nonpapillary, metaplastic squamous epithelium with nuclear atypic
  • Basal layer of uniform cells with a uniform chromatin pattern and variable hyperchromasia
  • Overlying squamous cells are monomorphic with prominent chromocenters and regular nuclear membranes
  • Normal cell polarity, rare / no cell crowding
  • Mitoses are < 1 per 10 HPF, normal (not atypical) and confined to lower third of epithelium
  • Occasionally higher mitotic rates, multinucleation, nuclear enlargement and perinuclear halos
Microscopic (histologic) images

Images hosted on other servers:
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Atypical immature metaplasia

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Atypical immature metaplasia

Use of immunostains to reclassify atypical immature metaplasia:
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Cytoplasmic CK17

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Positive stains
Reporting method
  • Atypical immature metaplasia is not commonly used as a diagnostic term in surgical pathology reports
  • Soslow et al. currently use diagnosis of HSIL if diffusely p16+ and hyperproliferative based on Ki67 (Arch Pathol Lab Med 2009;133:729)
  • HPV+, p16+ hypoproliferative lesions with Ki67+ may be early or regressing lesions
  • If immunostains do not support a proliferative, HPV associated lesion, diagnosis often includes explanatory note
Molecular / cytogenetics description
Differential diagnosis
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