Pronunciation: [ˈe͡əɹi͡əzstˈɛlə fɪnˈɒmɪnən] (IPA)

The arias-stella phenomenon, pronounced /əˈraɪəs ˈstɛlə fɪˈnɒmɪnən/, is a rare medical condition that occurs during pregnancy. It results in changes to the cells that line the uterus, leading to the formation of cysts and abnormal growths. This can cause bleeding, pain and infertility. The word 'arias-stella' is derived from the names of two researchers who first described the condition in the early 1900s, Eduardo Arias-Stella and Gustavo Fernando A. Stella. The spelling of the word reflects its Latin origins and its usage in medical terminology.

ARIAS-STELLA PHENOMENON Meaning and Definition

  1. Arias-Stella phenomenon is a medical condition characterized by changes in the cells that line the uterus, also known as the endometrium. Specifically, the condition is marked by the presence of large, glandular-like cells with eosinophilic cytoplasm and enlarged, hyperchromatic nuclei.

    These changes occur in response to the influence of hormones, predominantly progesterone, during a normal pregnancy or certain hormonal imbalances. The Arias-Stella phenomenon is commonly observed in women who experience an ectopic pregnancy (pregnancy outside the uterus), a molar pregnancy (abnormal growth of tissue inside the uterus), or a gestational trophoblastic disease (abnormal growth of cells in the uterus). It is also occasionally seen in women using certain hormonal medications.

    Histologically, the Arias-Stella phenomenon is characterized by the presence of atypical decidual cells, which are usually located glands of the endometrium. These cells differ from normal decidual cells by their enlarged size, altered shape, and increased cytoplasmic eosinophilia. The nuclei are often enlarged, hyperchromatic (darker staining), and contain irregular chromatin patterns.

    Clinically, the Arias-Stella phenomenon typically presents as abnormal bleeding or irregular menstrual periods. However, it is important to note that this condition is generally benign and does not require treatment unless it is associated with a specific underlying pathology, such as an ectopic pregnancy or molar pregnancy.

    In summary, the Arias-Stella phenomenon refers to the histological changes observed in the endometrial cells, involving the presence of large, glandular-like cells with eosinophilic cytoplasm and enlarged, hyperchromatic nuclei. In most cases, it is a benign finding associated with normal pregnancy or hormonal imbalances.


The term "Arias-Stella phenomenon" is named after two prominent pathologists and gynecologists, Dr. Godfrey H. R. Arias-Stella (1901-1991) and Dr. Neli Fidelia Arias-Stella (1931-2019). They were father and daughter, and both made significant contributions to the field of pathology.

The phenomenon was first described by Dr. Neli F. Arias-Stella in 1954. She observed certain changes in the cells lining the uterus of women during pregnancy. These changes, characterized by enlarged and hyperactive cells known as Arias-Stella reaction, were later termed the "Arias-Stella phenomenon" in recognition of her work.