Artifacts in Cervical Cytology: Cornflakes, Cockleburs, Glycogenation, Contaminants, Virtual Slides and MCQs

Pap smear with a cocklebur, cornflake artifact, an insect hair and a glycogenated cell

Subtitle: A practical guide to artifacts and contaminants in Pap smears: cornflake artifact, cockleburs vs Actinomyces, glycogenation vs koilocytes, insect parts, trichomes, air-drying and starch, with virtual slides and 10 MCQs.

Author: PathologyMCQ Editorial Board

Category: Cytopathology

Last Updated: October 2026

Read Time: 7 minutes

At-a-Glance

Artifacts come from preparation (cornflakes, air-drying); contaminants come from outside the patient (insect parts, plant trichomes, starch, pollen).
Physiological mimics such as glycogenated navicular cells and cockleburs are real but harmless findings, common in pregnancy.
Know the true lesion they mimic: koilocytes (LSIL), Actinomyces, Candida.
Cornflake artifact is fixed by remounting, not by repeating the smear.

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Quick Guide: Artifact or Lesion?

Before you call it abnormalAsk four questions

1Is it in the cell?Same focal planeContaminants and cornflakes often sit on top of cells, in a different plane.

2Are the nuclei normal?Size, chromatin, membraneGlycogen and air-drying change the cytoplasm or stain, not true nuclear atypia.

3Is it refractile or birefringent?PolariseStarch, crystals and some fibres light up; organisms do not.

4Does the clinical setting fit?Pregnancy, IUDCockleburs and navicular cells in pregnancy; Actinomyces with an IUD.

Rule: if it is too big, too regular or sitting in the wrong plane, think artifact or contaminant first.

Preparation Artifacts

Cornflake artifact

Cause: air trapped over cells when xylene evaporates before coverslipping.
Appearance: brown-black, refractile, flake-like deposits overlying cells and obscuring nuclei.
Fix: soak off the coverslip in xylene and remount. Do not repeat the smear for this alone.

Air-drying artifact

Cause: delayed fixation of conventional smears.
Appearance: enlarged, pale cells with smudged chromatin and poor staining.
Pitfall: can mimic atypia; extensive air-drying may make the smear unsatisfactory.

Physiological Mimics

Cockleburs (pseudoactinomycotic radiate granules)

Appearance: radiating arrays of thick, blunt, club-shaped, refractile golden-orange spokes, often ringed by histiocytes.
Setting: classically pregnancy.
Mimic of: Actinomyces, which are fine filamentous bacteria (not fungi) forming tangled “cotton ball” clumps, usually with an IUD.

Cocklebur artifact in a Pap smear — Cockleburs.

Glycogenation (navicular cells)

Appearance: boat-shaped intermediate cells with abundant yellow cytoplasmic glycogen.
Setting: pregnancy and progesterone effect (luteal phase, progestogens).
Mimic of: koilocytes (LSIL). Glycogen clearing is pale yellow and ill-defined with normal nuclei; koilocytes have a sharp cavity, dense rim and atypical nuclei.

Glycogenated navicular cells in a Pap smear — Glycogenated (navicular) cells.

Contaminants

Carpet beetle (dermestid) larval hairs

Appearance: large, brown, segmented bristles with an arrowhead or spear-shaped tip.
Source: environmental contamination of slides or reagents.
Pitfall: their size and segmentation can be mistaken for fungal or parasitic elements.

Carpet beetle larval hair contaminant in a Pap smear — Carpet beetle larval hair.

Trichomes (plant hairs)

Appearance: large, star-shaped or branching plant epidermal hairs.
Pitfall: may be mistaken for fungal elements. Note the spelling: trichome, not “trichrome” (the stain) or Trichomonas (the parasite).

Plant trichome contaminant in a Pap smear — Plant trichome.

Other contaminants to know

Starch granules from glove powder: round, refractile, “Maltese cross” under polarised light.
Pollen and Alternaria spores: environmental; Alternaria has brown, segmented, club-shaped conidia.
Lubricant or ultrasound gel: granular purple-blue background material that can obscure cells.
Cotton and synthetic fibres: refractile, often birefringent, lying in a different plane.

Mimic vs Real Lesion

Do not be fooled

Mimic	Looks like	How to tell them apart
Cockleburs	Actinomyces	Thick blunt refractile spokes vs fine branching bacterial filaments; pregnancy vs IUD
Navicular cells	Koilocytes (LSIL)	Yellow, ill-defined glycogen with normal nuclei vs sharp cavity and nuclear atypia
Air-drying	Atypia, HSIL	Pale, smudgy staining across many cells vs crisp hyperchromatic nuclei
Insect hairs, trichomes	Fungi	Size, segmentation and arrowhead tip; different focal plane
Cornflakes	Pigment	Refractile brown flakes over cells; clears on remounting

Virtual Slides

Compare true Actinomyces with what you have learned about cockleburs, then review a normal smear. Tap an annotated region to zoom to it.

Virtual slides · Pap smearsReal lesion vs normal background

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What to look for

Drag to pan · pinch or double-tap to zoom · use the + / − buttons

Test Yourself: 10 MCQs

Cervical cytology artifacts: 10 MCQs

Artifacts, contaminants and mimics, with instant explanations.

Score: 0 / 10

More practice: the gynaecological pathology MCQ bank →

Exam Pearls

Cornflake artifact: trapped air after xylene dries; remount.
Cockleburs: blunt golden spokes, pregnancy. Actinomyces: fine filamentous bacteria, IUD.
Navicular cells: yellow glycogen, normal nuclei; not koilocytes.
Carpet beetle hairs: segmented with an arrowhead tip.
Trichomes are plant hairs; starch shows a Maltese cross.

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