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Benign / non-neoplastic lesions

Arias-Stella reaction

Reviewer: Farnaz Hasteh, M.D., UCSD Medical Center (see Reviewers page)
Revised: 12 November 2010, last major update November 2010
Copyright: (c) 2006-2010, PathologyOutlines.com, Inc.


● Pregnancy related changes that without a clinical history may appear worrisome, including cytomegaly, enlarged nuclei, smudgy chromatin, frequent nuclear inclusions, prominent nucleoli


● Named for Peruvian pathologist (Wikipedia)

Clinical features

● Often overdiagnosed as SIL, but pregnant women with atypical glandular lesions (AGUS) may have SIL on subsequent biopsy (Acta Cytol 2001; 45:294)
● Arias-Stella changes disappear after pregnancy
● Pathologists are often not told patient is pregnant or post-partum (Acta Cytol 1995; 39:905)

Case reports

● Cervicovaginal smear of nonpregnant woman undergoing infertility treatment with clomiphene and beta-hCG (Diagn Cytopathol 2005;32:94)
● 33 year old with Arias-Stella reaction in pap smear due to uterine adenomyomatomatous polyp (Acta Obstet Gynecol Scand 2007;86:106)
● 35 year old with Arias-Stella reaction due to cervical pregnancy (Acta Cytol 1994;38:218)

Cytology description

● Cytomegaly with dense variable cytoplasm, nucleomegaly, high N/C ratio, round/oval nuclei with smudgy chromatin, frequent nuclear inclusions, prominent nucleoli
● No crowding, no mitosis

Micro images

Histology (not cytology) images of endometrium (not cervix)


The gland outlines are complex, resembling tortuous late secretory endometrial glands. The stroma is cervical not endometrial in character. The cytoplasm of glandular cells is vacuolated, and an occasional nucleus is enlarged, hyperchromatic, and protrudes into the lumen, i.e., so-called hobnail cells.

Differential diagnosis

● Clear cell adenocarcinoma: clinical mass, desmoplasia, infiltrative, high N/C ratio, marked atypia, mitotic figures (Am J Surg Pathol 2004;28:608)
● Radiation or chemotherapy induced changes
● Glandular atypia

End of Cervix-cytology > Benign / non-neoplastic lesions > Arias-Stella reaction

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