Cervix - Cytology
Benign cells / nonneoplastic lesions
Squamous metaplasia

Topic Completed: 1 March 2011

Revised: 21 December 2018, last major update March 2011

Copyright: (c) 2006-2017, PathologyOutlines.com, Inc.

PubMed search: Squamous metaplasia [title] cervix

Farnaz Hasteh, M.D.
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Cite this page: Hasteh F. Squamous metaplasia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cervixcytologysquamousmetaplasia.html. Accessed November 12th, 2019.
Definition / general
  • Common metaplastic process that occurs in transformation zone
  • Common during puberty, pregnancy and postpartum
  • During the reproductive years, the transformation zone (where metaplasia occurs) is distal to external cervical os
  • In the postmenopausal years, the T zone may become more proximal and within the endocervical canal
  • Due to proliferation of reserve cells under columnar cells
  • First step in the process is reserve cell hyperplasia; then squamous differentiation begins which is immature; then mature squamous metaplasia, which fills endocervical glands
  • Promoted by increased acidity at puberty, inflammation, polyps, OCP (oral contraceptive) use
Prognostic factors
Cytology description
  • Immature squamous metaplasia
    • Associated with endocervical cells
    • Arranged in cobblestone pattern (jigsaw pattern) or singly
    • Parabasal like cells with dense, dark cytoplasm reduced in quantity, increased N/C ratio
    • Blue cytoplasm with sharp cell border; often cytoplasmic vacuoles
    • Round to oval nuclei with smooth membrane and fine chromatin
    • Spidery forms are common
    • Nucleoli are present if reactive process
    • May resemble reserve cell hyperplasia
    • In liquid based cytology, they have higher N/C ratio and can mimic HSIL
  • Mature squamous metaplasia
    • Resembles intermediate cells but with denser cytoplasm and rounded cell outlines
    • Normal N/C ratio
Cytology images

Images hosted on other servers:

Various images

Immature squamous and transitional (urothelial) metaplasia

Contributed by: Dr. Marilin Rosa,
University of Florida (USA)

Differential diagnosis
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