In the PALM-COEIN framework, adenomyosis is categorized as which type of etiology?

• A. Non-structural (COEIN)
• B. Not defined
• C. Structural (PALM)
• D. Both

Answer: (C)

Key idea: In the PALM-COEIN framework, causes of abnormal uterine bleeding are split into structural (PALM) versus non-structural (COEIN). Adenomyosis is a structural cause because it represents a definable anatomic lesion within the uterine wall—endometrial tissue growing into the myometrium. This makes it part of the PALM group (polyp, adenomyosis, leiomyoma, malignancy). The non-structural group covers functional or systemic etiologies like coagulopathy, ovulatory dysfunction, endometrial factors not tied to a discrete lesion, iatrogenic factors, and those not yet classified. Since adenomyosis is an identifiable structural abnormality, it belongs to the structural category and not to non-structural or undefined.