Adolescent and Early-Onset Adenomyosis: Phenotypes, Diagnostic Challenges, and Fertility-Conscious Care.

Adolescent and early-onset adenomyosis is increasingly recognized in symptomatic young patients, but its clinical significance remains uncertain. This narrative review synthesizes English-language literature on adolescent and early-onset adenomyosis, distinguishing direct adolescent and young-adult evidence from supportive evidence derived from adult populations. Current data suggest that adenomyosis-like imaging features may be identified in adolescents with severe dysmenorrhea, heavy menstrual bleeding, chronic pelvic pain, or coexisting endometriosis. Early disease often appears as subtle diffuse inner-myometrial change, focal lesions, or cystic/juvenile forms rather than the classic diffuse adult phenotype. Ultrasound is the first-line imaging modality, whereas MRI is reserved for equivocal findings, atypical cystic lesions, suspected congenital anomalies, or endometriosis overlap. Management requires a stepwise, symptom-oriented approach that considers future reproductive options and avoids unnecessary uterine intervention. Overall, adolescent adenomyosis should be considered in patients with severe or treatment-resistant menstrual symptoms, while uncertain imaging findings should not be overinterpreted.