Arias-Stella reaction

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.

Synopsis

 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

IHC

 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

• endometrial anomalies
  • endometrial epithelial anomalies
  • endometrial stromal anomalies

References

 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