The gross specimen of an ovarian mass shown above demonstrates a unilocular cyst containing yellowish, greasy material and abundant hair. This finding is most characteristic of which of the following ovarian neoplasms?

Explanation

## Image Findings * Gross specimen of a unilocular cystic ovarian mass. * The cyst lumen contains abundant dark, coarse hair. * Yellowish, greasy material (consistent with sebum) is visible coating the inner surface of the cyst wall and mixed with the hair. * The cyst wall appears relatively thin and smooth in areas not covered by hair. ## Diagnosis **Key Point:** The presence of **hair** and **sebaceous material** within an ovarian cyst is pathognomonic for a **mature cystic teratoma** (dermoid cyst). Mature cystic teratomas are benign germ cell tumors that arise from totipotential germ cells. They are characterized by the presence of mature tissues derived from all three embryonic germ layers (ectoderm, mesoderm, and endoderm). Ectodermal derivatives, such as skin, hair follicles, sebaceous glands, and sweat glands, are the most common and visually striking components, leading to the classic appearance seen in the image. The yellowish, greasy material is sebum produced by sebaceous glands, and the hair is a product of hair follicles. ## Differential Diagnosis | Feature | Mature Cystic Teratoma (Dermoid Cyst) | Serous Cystadenoma | Mucinous Cystadenoma | Endometrioma | | :------------------ | :------------------------------------ | :------------------------- | :------------------------- | :---------------------------- | | **Contents** | Hair, sebum, teeth, bone, cartilage | Clear, watery fluid | Thick, gelatinous mucin | Thick, dark 'chocolate' fluid | | **Germ Layers** | All three (ectoderm dominant) | Surface epithelium | Surface epithelium | Endometrial tissue, blood | | **Gross Appearance**| Cyst with hair, greasy material | Smooth-walled cyst, clear fluid | Multilocular, thick mucin | 'Chocolate cyst', fibrous wall | ## Clinical Relevance **Clinical Pearl:** Mature cystic teratomas are the **most common ovarian germ cell tumors** and account for 10-20% of all ovarian neoplasms. They are typically benign but carry a small risk of malignant transformation (usually to squamous cell carcinoma) and are prone to complications like **torsion** due to their weight. ## High-Yield for NEET PG **High-Yield:** Mature cystic teratomas are often referred to as **dermoid cysts** because of the prominent ectodermal differentiation (skin, hair, sebaceous glands). They are usually unilateral but can be bilateral in 10-15% of cases. **Key Point:** On imaging (ultrasound, CT, MRI), characteristic features include fat-fluid levels, calcifications (representing teeth or bone), and a Rokitansky nodule (dermoid plug). ## Common Traps **Warning:** Do not confuse the contents of a dermoid cyst with other cystic ovarian lesions. The presence of hair and sebaceous material is unique to teratomas. Other cysts have distinct fluid characteristics (e.g., clear for serous, gelatinous for mucinous, chocolate-like for endometrioma). ## Reference [cite:Robbins Basic Pathology, 10th Edition, Chapter 22, The Female Genital Tract]