Premalignant / preinvasive lesions - H&E

SIL variants

Topic Completed: 1 May 2007

Minor changes: 18 February 2021

Copyright: 2007-2019 PathologyOutlines.com, Inc.

PubMed Search: SIL Variant cervix

See subtypes below: Atypical immature metaplasiaCondyloma-immatureHSIL with immature metaplastic differentiationHSIL with eosinophilic dysplasia

Branko Perunovic, D.M.
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Cite this page: Perunovic B. SIL variants. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cervixSILvariant.html. Accessed December 3rd, 2021.
Atypical immature metaplasia
Definition / general
  • Controversial term not accepted by most gynecologist pathologists
  • Poorly reproducible diagnosis which lacks a uniform definition; spans a morphologic spectrum and includes many diagnostically challenging cases with an immature appearance
  • 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
  • HPV+ cases are associated with future diagnosis of HSIL
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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Definition / general
  • Also called papillary immature metaplasia, immature exophytic LSIL, squamous papilloma
  • Considered a variant of LSIL
  • Infection of transformation zone epithelium that fails to mature, maintains a phenotype resembling immature metaplasia
  • Involves proximal transformation zone and endocervix
  • Strongly associated with HPV subtypes 6 and 11 (Mod Pathol 1992;5:391)
  • Excisional biopsy, diathermy or laser vaporization
Microscopic (histologic) description
  • Patterns of immature condyloma include:
    1. Close similarity to squamous metaplasia with
      1. Mild increases in nuclear cytoplasmic ratio
      2. Preservation of nucleoli
      3. Slight nuclear crowding
      4. A near absence of keratinocyte maturation
    2. Formation of small slender filiform papillae (pathognomic)
    3. Frequent preservation of overlying columnar cells
    4. No / rare mitotic figures
Microscopic (histologic) images

Contributed by Seema Khutti, M.D.

Slender papillae 100x

Slender papillae 200x

Slender papillae 400x


HSIL with immature metaplastic dysplasia
Differential diagnosis
  • Air drying artifact
  • Papillary immature metaplasia: papillary not flat, less nuclear pleomorphism and atypia

HSIL with eosinophilic dysplasia
Definition / general
  • Present in 10% of HSIL lesions
  • Associated with HPV infection and classic HSIL in adjacent areas
  • May arise from metaplastic cervical squamous epithelium that has become infected with high risk HPV
Microscopic (histologic) description
  • Lack of normal maturation
  • Compared to classic HSIL, cells have distinct cell borders and abundant eosinophilic cytoplasm, increased N/C ratio and focal dysplastic nuclei with nuclear enlargement, hyperchromasia, variable nuclear membrane abnormalities and distinct nucleoli
  • Associated with classic SIL and squamous metaplasia
Positive stains
Differential diagnosis
Additional references
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