Dermoid cysts are a common type of growth that can develop in various parts of the body. These cysts are typically present from birth, though they may not become noticeable until later in life. While dermoid cysts are overwhelmingly benign, there is a very rare possibility they can become malignant.
What Are Dermoid Cysts
Dermoid cysts are a type of teratoma, growths formed from germ cells. They originate during embryonic development when skin cells and other tissues become trapped in an unusual location. They are considered congenital.
These growths commonly occur where embryonic skin layers fuse, such as the head and neck, near the eyebrows, in the ovaries, or along the spine. A dermoid cyst contains mature tissues and structures typically found in the skin, like hair follicles, sweat glands, and oil glands. They can also contain other tissues such as hair, teeth, bone, and nerve tissue.
The contents within the cyst continue to produce materials like oily fluid (sebum) and shed skin cells, causing the cyst to slowly enlarge over time. Dermoid cysts are classified as mature cystic teratomas, characterized by the presence of well-developed, differentiated tissues. They generally grow slowly.
When Dermoid Cysts Become Cancerous
While dermoid cysts are almost always benign, malignant transformation is a very rare event, occurring in less than 1% to 3% of cases. This transformation typically involves mature tissues within the cyst changing into cancerous cells. Squamous cell carcinoma is the most common type of cancer arising from a dermoid cyst, accounting for approximately 80% to 85% of such malignant changes.
Other, less common, types of cancer can also develop, including adenocarcinoma, melanoma, carcinoid tumors, or thyroid carcinoma. It is important to distinguish this from immature teratomas, which are inherently malignant from formation and contain immature or embryonic tissues. Malignant transformation refers specifically to a previously benign mature dermoid cyst developing cancerous characteristics.
Certain factors may slightly increase the rare risk of malignant transformation. These include larger cyst size, particularly those over 10 cm, and older age, especially in women over 40 or postmenopausal individuals. Despite these potential risk factors, the overall incidence of a dermoid cyst becoming cancerous remains exceptionally low.
Identifying and Managing Malignancy
Identifying potential malignancy in a dermoid cyst often begins with imaging studies. Ultrasound is frequently the initial diagnostic tool, as dermoid cysts have a distinctive appearance that can be identified with high accuracy. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans provide more detailed images, especially for deeper cysts, helping assess characteristics and relationship to surrounding structures.
Blood tests for tumor markers, such as CA-125, may be ordered, particularly for ovarian dermoid cysts. While CA-125 can be elevated in various benign conditions, significantly high or rising levels might suggest malignancy, though it is not a definitive indicator on its own.
The definitive diagnosis of malignancy requires pathological examination of the cyst tissue after surgical removal. For benign dermoid cysts, management often involves monitoring, especially if they are small and asymptomatic. However, surgical removal is the primary treatment for dermoid cysts, particularly if they are causing symptoms, are large, or if there is any suspicion of malignancy.
If malignancy is confirmed, the treatment approach is tailored to the specific type and stage of cancer. This often involves more extensive surgery, which may be followed by chemotherapy or radiation therapy, depending on the cancer’s characteristics and spread. Prognosis varies significantly based on factors like the cancer type, its stage, and whether it has extended beyond the cyst capsule.