A lump or mass in the neck often poses particular challenges.
It’s not a simple “just cut it out and
let’s be done with it” approach. First
of all, we must determine the cause in order to render the proper
treatment. The workup can be quite
involved as a prior post explains (Neck
Mass: Not Every Lump is A Tumor, But…It Might Be) since there could be numerous
potential causes for the mass. As that
post explains, there are three major causes of neck lumps: congenital,
inflammatory/infectious and neoplastic (tumor).
A congenital mass arises
from something that existed at birth.
These types of masses often are quite small rendering them unnoticeable
physically. They often are dormant and
remain small, presenting themselves sometimes years later. They then become visible and/or palpable
(noticeable by touch or feel). One such congenital
mass is the thyroglossal duct cyst.
A
thyroglossal duct (from herein I’ll abbreviated it as TGD) anomaly presents itself as a mass or draining fistula.
Usually, it is a mass, one that typically is painless. The mass is a typically a cyst—a fluid filled sac surrounded by a
thin capsule of tissue. Sometimes these
become infected, rupture through the overlying skin and drain. This is termed a fistula.
This
typically occurs in children, but I’ve seen TGD anomalies in adults, the oldest
was over 60 years old. I’ve removed one in
a seven-year-old girl, and ten years later in her 50 year-old father. The theory here is the TGD cyst remains
dormant and very small until one day for some unknown reason, the lining tissue
starts secreting fluid, causing the cyst to grow, much like an expanding water
balloon.
The TGD
cyst or fistula tract is usually benign, though there have been rare cases of
cancer discovered within, usually thyroid cancers, and often removal of the anomally
with the small focus of cancer is curative.
Thus, it is important to send the specimen to the pathologist for
thorough study.
Embryology
(early stages of formation during pregnancy)
The
source of a TGD anomaly arises from the embryonic path of the thyroid gland as
it develops during embryologic formation in
utero (inside the uterus). The
thyroid gland forms as a bud of tissue arising from the base (or back part) of
the tongue known as the foramen cecum. As the embryo grows and develops into a fetus,
this thyroid tissue descends, migrating lower in the neck to eventually reside
below the larynx or voice box in the
normal location for the thyroid gland.
The intervening tract from foramen cecum to the thyroid gland
obliterates. However, sometimes a
remnant along that tract persists, giving rise to a cyst or fistula. The location of a TGD anomaly can thus be
found anywhere along that embryologic path, from the base (back or posterior
part) of the tongue to the upper neck below the chin (the submental area) all the way to the lower part of the neck (see the
figure at the beginning). TGD anomalies
are midline or close to midline, rather than off to one side of the neck.
Surgery: The Sistrunk Procedure
Due to the embryologic path thus described, surgery for a TGD
anomaly requires not only removal of the cyst and/or fistula tract, but also
its source. This requires following the
tract leading to the anomaly upwards towards the base of the tongue. Since the tract adheres to the hyoid bone, the central part of this
bone is removed. This is known as the Sistrunk Procedure. Take heart though that
no functional compromise to voice or swallowing occurs with this maneuver as
the voice box (larynx) lies below and muscles of swallowing are preserved. Prior to the Sistrunk Procedure, the rate of recurrence for TGD anomalies was very high with simple excision.
An incision is made horizontally over the mass, or if a
fistula is present, the incision also incorporates the skin surrounding the
opening into the fistula. The strap muscles (bands of muscles running
from top to bottom of the front part of the neck) are then separated in the
midline and retracted outwards,, since the source of the TGD is midline. Careful dissection is required to identify
the anomaly. Once the TGD anomaly has
been isolated, dissection is carried upwards to the hyoid bone. Cuts through the bone are made on each side of
the tract and the central part of the hyoid is removed, exposing muscle of the
base of tongue. A small portion of this
muscle is removed to take away any remnants of the tract, and this area is then
closed in a purse-string fashion. The
strap muscles are reapproximated in the midline with absorbable sutures and the
subcutaneous (below the skin) tissue and skin are reapproximated with
sutures. Sometimes a small drain is
placed in the wound and out one side of the incision and removed the next
day. Pain medication can be prescribed,
but many times over-the-counter medications such as acetaminophen (Tylenol) or
ibuprofen (Motrin, Advil) are all that’s required, especially in children.
An excised TGD cyst from another patient
Children (and adults) typically tolerated this surgery quite
well. Often the patient is eating
normally in a day or two and back to normal activity within a week, though we
instruct parents to keep their activity light for at least a week and avoid
manipulating the surgical site. With
time as the incision heals, it becomes rather unnoticeable.
©Randall S. Fong, M.D.
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