Uterine lesions with plexiform morphology are uncommon lesions with debated histogenesis. Despite being an incidental and usually benign finding (plexiform tumorlet), some cases can pose diagnostic problems. Their paucity in the recent literature adds to these difficulties and often causes ambiguities. The objective of this study is to systematically review published cases to highlight the historical aspects of their recognition, reappraising their morphology, histogenesis, and differential diagnosis.
English literature is reviewed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and 32 reports are analyzed.
Most cases are reported in the fourth to sixth decades. In most cases (66.7%), plexiform lesions are incidental findings while 33.3% of cases have been the chief pathology. Size varies from 0.5 to 195 mm. Plexiform foci were solitary in 78.2% cases and multiple in 21.8%. In 67.8% of cases, the lesions are reported as myometrial, while 32.2% are arising from endometrial stroma. Immunohistochemistry shows smooth muscle and no sex cord marker expression. They are usually benign lesions, but worrisome features include plexiform morphology in disseminated peritoneal leiomyomatosis, intravenous leiomyomatosis, and diffuse uterine leiomyomatosis.
Plexiform lesions represent a diverse pathology varying from epithelioid leiomyomas to epithelioid smooth muscle metaplasia of endometrial type of stroma.

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