40. The Adnexal Mass and Ovarian Tumour Classification

First principle: classify, then risk‑stratify by age and features

First separate functional cysts (follicular, corpus luteum, theca‑lutein — often resolve) from neoplasms, which fall into three families:

The common benign one

Mature cystic teratoma (dermoid) — benign germ‑cell tumour, young women, contains all three germ layers; main risk is torsion (acute pain, an emergency). 🚩

Assessing malignancy risk

Integrate age, menopausal status, symptoms, ultrasound morphology (RMI‑type reasoning), and markers.

The screening gap (a key exam contrast)

Pitfalls

• Ordering CA‑125 as a "rule‑out" in a premenopausal woman (false positives from endometriosis etc.).
• Missing torsion in a young woman with an acutely painful dermoid.

Pearls

• 🎯 Functional vs neoplastic; epithelial‑old / germ‑cell‑young / sex‑cord‑hormonal. CA‑125 ≠ screening.
• 🩺 Acute pain + adnexal mass in a young woman → exclude torsion urgently.

Next → The malignancy itself — why it hides, and its clues (Concept 41).