My 22-year-old daughter has just been diagnosed with a branchial cleft cyst. It has been badly infected but is now just a mass. The doctor is keeping her on antibiotics until surgery can be scheduled to remove it. How serious is this surgery? How invasive?

H.

How serious and invasive is this operation? This is a tough question. The answer depends on which type of branchial cleft cyst your daughter has. You see, there are a few different types of these cysts, and the risks of the operation depend on the type of cyst.

To understand why this is so, you need to know something about the branchial apparatus. During a very early phase of embryonic development, the "neck" of the embryo consists of branchial arches and clefts. The branchial apparatus is similar in appearance to the gill apparatus of fish. The first branchial cleft ("gill slit") is the one closest to the top of the head, the second branchial cleft is below it and so forth.

Each cleft can potentially give rise to a cyst. Cysts that arise from different clefts have different anatomical relationships. That's because the branchial arches ("gills," to continue the analogy) develop into many of the structures of the head and neck: the ears, jaws and many of the major nerves, arteries and veins -- to name a few. A cyst arising from the first cleft will be intimately associated with first and second arch structures; a cyst arising from the second cleft will be associated with second and third arch structures.

In humans, the most common branchial cleft cysts are those that arise from the second cleft. These cysts are usually found in the middle third or lower third of the neck and are closely associated with the great vessels of the neck. First branchial cleft cysts, on the other hand, may be found in front of the ear or just below the jaw. Many first branchial cleft cysts are closely associated with the facial nerve (the nerve that allows you to smile, frown, wrinkle your forehead and close your eyes).

If your daughter has a second branchial cleft cyst, the surgeon may run afoul of the great vessels of the neck; if she has a first branchial cleft cyst, the surgeon must show caution with regard to the facial nerve. For other branchial cleft cysts (which are all fairly rare), other anatomical pitfalls exist.

Back to your questions. All operations are invasive, and all operations are serious. Adjectives describing the invasiveness or seriousness of an operation are worthless, in my opinion. What your daughter must receive from her doctor are a description of the operation, the intended benefit of the operation, alternatives (if any) to the operation and a full discussion of the risks involved. This discussion is known as informed consent. Beware the surgeon who skimps on the informed consent discussion!