Histopathology of complex<unk>  without atypia: Cystically dilated endometrial glands lined by a single layer of columnar epithelium. Histopathology of complex<unk>  with atypia: Closely packed endometrial glands with sparse intervening stroma and stratification of the lining epithelium. Epithelial cells show cytological atypia with high nucleocytoplasmic ratio, irregular clumping of nuclear chromatin, and mitotic figures. Like other hyperplastic disorders,<unk>  initially represents a physiological response of endometrial tissue to the growth-promoting actions of estrogen. However, the gland-forming cells of a hyperplastic endometrium may also undergo changes over time which predispose them to cancerous transformation. Several histopathology subtypes of<unk>  are recognisable to the pathologist, with different therapeutic and prognostic implications. The most commonly used classification system for<unk>  is the World Health Organization (WHO) system, which previously had four categories: simple<unk>  without atypia, complex<unk>  without atypia, simple atypical<unk>  and complex atypical<unk> . In 2014, the WHO updated the classification system and removed the distinction between simple or complex<unk> , instead only on presence or absence of atypia. *<unk>  (simple or complex) - Irregularity and cystic expansion of glands (simple) or crowding and budding of glands (complex) without worrisome changes in the appearance of individual gland cells. In one study, 1.6% of patients diagnosed with these abnormalities eventually developed endometrial cancer. * Atypical<unk>  (simple or complex) - Simple or complex architectural changes, with worrisome (atypical) changes in gland cells, including cell stratification, tufting, loss of nuclear polarity, enlarged nuclei, and an increase in mitotic activity. These changes are similar to those seen in true cancer cells, but atypical<unk>  does not show invasion into the connective tissues, the defining characteristic of cancer. The previously mentioned study found that 22% of patients with atypical<unk>  eventually developed cancer.
Endometrial hyperplasia
Uterine hyperplasia
Endometrial polyp
Adenomyosis
Cervical pregnancy
Chronic deciduitis
Obstetric transition
Strawberry cervix