Arias-Stella reaction


Arias-Stella reaction, also Arias-Stella phenomenon, is a benign change in the endometrium associated with the presence of chorionic tissue.
Arias-Stella reaction is due to progesterone primarily. Cytologically, it looks like a malignancy and, historically, it was diagnosed as endometrial cancer.

Significance

It is significant only because it can be misdiagnosed as a cancer. It may be seen in a completely normal pregnancy.

Diagnosis

It is characterized by nuclear enlargement and may also have any of the following: an irregular nuclear membrane, granular chromatin, centronuclear vacuolization, and pseudonuclear inclusions.
Five subtypes are recognized:
  1. Minimal atypia.
  2. Early secretory pattern.
  3. Secretory or hypersecretory pattern.
  4. Regenerative, proliferative or nonsecretory pattern.
  5. Monstrous cell pattern.

    History

It was first described by Javier Arias Stella, a Peruvian pathologist, in 1954.