Atrophic Pattern with Predominantly Parabasal Cells in Pap Smear
An atrophic pattern with predominantly parabasal cells on a Pap smear indicates benign cellular changes due to estrogen deficiency, most commonly seen in postmenopausal women, and typically requires only repeat cytology in 3 months if severe inflammation is present, or routine follow-up if the smear is otherwise normal. 1, 2
What This Finding Represents
Parabasal cell predominance reflects hypoestrogenic state where the cervical epithelium becomes thin and immature, with cells from deeper layers (parabasal cells) appearing on the surface rather than mature superficial squamous cells 1
This is a benign, non-neoplastic finding that represents physiologic changes related to decreased estrogen levels, not cervical dysplasia or malignancy 2, 3
Most commonly occurs in postmenopausal women but can also be seen in breastfeeding women, those on certain medications (like aromatase inhibitors), or women with premature ovarian insufficiency 1
Critical Diagnostic Pitfall
The major clinical concern is that atrophic changes can mimic high-grade squamous intraepithelial lesion (HSIL) cytologically, leading to false-positive interpretations and unnecessary invasive procedures 3, 4, 5, 6:
Atrophic parabasal cells may show nuclear enlargement, hyperchromasia, and irregular nuclear membranes that can be misinterpreted as dysplasia 3, 5, 6
Studies demonstrate that Pap smears with atrophic cellular patterns have significantly higher false-positive rates for high-grade lesions compared to non-atrophic smears 6
Research shows that 86% of false-positive cytologic diagnoses in postmenopausal women with atrophy can be avoided using ancillary testing 4
Recommended Management Algorithm
If Atrophy is the Only Finding (No Atypia):
Resume routine screening intervals with no need for colposcopy or additional testing 2
Consider estrogen therapy (topical preferred) to improve specimen adequacy for future screening 1
If Atrophy with Reactive/Inflammatory Changes:
Repeat Pap smear in 3 months after treating any underlying infection 2
Treat identified infections before obtaining repeat specimen 2
If Atrophy with Atypical Cells (ASC-US or Higher):
Do NOT immediately proceed to colposcopy - this is where overtreatment commonly occurs 3, 6
Prescribe vaginal estrogen therapy (typically 2-4 weeks of topical estrogen) 1, 3
Repeat Pap smear 1-2 weeks after completing estrogen course 3
If repeat smear normalizes after estrogen, return to routine screening 3, 4
If atypia persists after estrogen therapy, then proceed to colposcopy 1
Special Considerations for Postmenopausal Women
Technical challenges in obtaining adequate specimens are common in postmenopausal women with atrophy 1:
The squamocolumnar junction may be inaccessible due to atrophic vagina and stenotic cervical os 1
Use gentle circular scraping with spatula followed by endocervical brush rotation 1
If severe cervicitis is present, consider deferring Pap smear until after antibiotic therapy to obtain optimal specimen 2
When to Suspect True Dysplasia Despite Atrophy
Be aware that HPV16 infection can cause vacuolated parabasal cells that may appear in atrophic backgrounds but actually represent true CIN2+ lesions 7:
If patient is HR-HPV positive (especially HPV16) with atypical parabasal cells, maintain higher suspicion 7
In HPV16-positive cases with vacuolated parabasal cells, 80% had CIN2+ on biopsy 7
HR-HPV testing can help stratify risk in atrophic smears with atypia, similar to its use in ASC-US triage 1
Key Clinical Pearls
Atrophic changes are distinct from ASC-US - these are separate diagnostic categories with different management pathways 2
The Pap smear is not effective for STD screening, so additional testing may be needed if infection is suspected clinically 2
Proliferation markers (Ki-67/MIB-1) can reliably distinguish atrophy from dysplasia if diagnostic uncertainty persists, with negative staining indicating benign atrophy in 96-100% of cases 3, 4