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Arias-Stella reaction

Tuesday 27 April 2004

Arias-Stella’s effect, Arias-Stella’s phenomenon


Definition: Highly excretive gland epithelium due to increased gonadotropin stimulation. An endometrial gland cell abnormality consisting of hyperchromatic nuclei, which may be present in normal or ectopic pregnancy.

The Arias-Stella reaction (ASR) can mimic endometrial clear cell carcinoma (ECCC) in small biopsies, especially when drug or pregnancy history is unknown.


- vacuolated clear cytoplasm
- intraglandular tufts
- hobnail cells
- oxyphilic cytoplasm
- delicate filiform papillae
- intranuclear pseudoinclusions
- cribriform intraglandular growth

- superficial glands
- deep glands
- confluent or extensive gland involvement

Differential diagnosis

- cervical clear cell carcinoma

  • lack of a mass suspicious for cancer
  • absence of a desmoplastic response
  • lack of an infiltrative pattern
  • spectrum of cytologic atypia
  • low nuclear-cytoplasmic ratio
  • usual lack of mitotic activity


- Naspin A and HNF-1β are frequently expressed in both gestational and nongestational ASR, and ER expression is usually either reduced or loss. Interpretation of these markers in small biopsies containing atypical clear cells should be made with caution. (30608233)

See also

- uterine anomalies


- Nucci MR, Young RH. Arias-Stella Reaction of the Endocervix: A Report of 18 Cases With Emphasis on Its Varied Histology and Differential Diagnosis. Am J Surg Pathol. 2004 May;28(5):608-612. PMID: 15105648