This letter originally appeared in Dr. Hoffman's column on allHealth.com. |
Q: My son has a cyst on the middle of his throat and the doctor says it is a dermoid cyst. What is a dermoid cyst? Does it have to be removed? What are the complications?
A: Dermoids are benign (non-cancerous) tumors that, under the microscope, look similar to skin tissue – hence the name "dermoid." Usually, dermoids in the neck are firm lumps that are attached to the overlying skin. When they occur in the central portion of the neck, they must be distinguished from other benign masses that may grow in this region: normal or inflamed lymph nodes, an enlarged central lobe of the thyroid gland, lipomas (fatty tumors), and thyroglossal duct cysts.
I’d like to digress a bit about thyroglossal duct cysts. The thyroglossal duct is a channel that is present in the developing fetus, but it has usually disappeared by the time the baby is born. Occasionally, a bit of the duct will remain intact and will give rise to a cyst, typically in the first 20 years of life. Thyroglossal duct cysts must be removed in their entirety. The cyst, and its associated duct, must both be removed, or else there is a very high recurrence rate. In contrast, the operation to remove a dermoid is just a simple excision of the dermoid itself. The two operations are very different. Thus, it is important that your son’s physician be fairly certain that he does not have a thyroglossal duct cyst. (One way to tell the difference: hold the lump between your fingers and ask your son to swallow. A thyroglossal duct cyst will bob up and down with the swallow; a dermoid, and most other masses, will not bob.)
Cancer is rare in children, but not nonexistent. Possibilities include lymphoma (a cancer of the lymph nodes) and other, rarer malignant tumors. Cancer is always in the back of my mind when I see a child with a neck mass. So, when you ask, "Does it have to be removed," my response is, "How willing are you to accept uncertainty as to the identity of the mass?"
In general, there are always 3 options for a neck mass, and your son’s situation is no exception. The options are: observation, fine needle aspiration biopsy, and excisional biopsy.
Observation is just that: you and your son’s doctor will "keep an eye on the lump." Is it growing? Does it hurt him? Does it get infected? Is he bothered by it in any way (for example, a school-aged child might become the object of ridicule over something as trivial as a lump in the neck!) If you opt for observation, you agree to visit the doctor on a regular basis, returning to the doctor sooner should the mass change significantly. Also, by opting for observation, you accept the fact that if this mass is malignant, your decision could endanger your son’s life. Admittedly, malignancy is very uncommon, but you should ask his doctor about this possibility very directly, should you opt for observation.
Incidentally, if the doctor thinks the mass is an inflamed lymph node, he may place the child on antibiotics for a short period of time to see whether the mass shrinks. Also, a skin test for tuberculosis is often a good idea, as tuberculosis (TB) and similar infections can cause enlargement of neck lymph nodes.
Fine needle aspiration biopsy (FNA) involves the use of a slender needle to obtain a sample of cells from the lump. This can yield a diagnosis, but will not remove the lump. Depending upon the age and maturity of the child, FNA may require sedation or even general anesthesia. FNA itself is a very low risk procedure, but sedation and anesthesia are not without risk. Also, FNA is subject to sampling error. In other words, the needle may miss the tumor or it may obtain an insufficient sample of cells (and the pathologist’s report would read something like this: "Inadequate material for diagnosis, suggest repeat FNA or excisional biopsy").
Excisional biopsy refers to surgical removal of the lump. This is the only way to (1) obtain a definitive diagnosis and (2) rid your son of the lump.
What are the risks of the operation to remove a dermoid? You should certainly have a thorough discussion of this with your son’s doctor, since there may be circumstances unique to your son to which I am not privy. However, the risks would certainly include: bleeding, infection, postoperative pain, and recurrence (the mass could come back). There will certainly be a scar, but some people scar worse than others – so another risk of surgery would be a cosmetically unpleasant scar. Finally, the operation would probably require a general anesthetic, which carries certain risks that the anesthesiologist could discuss with you. Your son’s doctor could give you the best estimate of the magnitude of the surgical risks.