Ectopic Lingual Thyroid Masquerading as Thyroid Cancer Metastases
Shehzad Basaria,
William H. Westra and
David S. Cooper
Department of Medicine, Division of Endocrinology (S.B., D.S.C.),
and Department of Pathology (W.H.W.), The Johns Hopkins University
School of Medicine, and Sinai Hospital of Baltimore (D.S.C.),
Baltimore, Maryland 21215
Address correspondence and requests for reprints to: David S. Cooper, M.D., Director, Division of Endocrinology, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Hoffberger Building, Suite 56, Baltimore, Maryland 21215. E-mail: dcooper{at}lifebridgehealth.org
 |
Introduction
|
---|
The endocrine literature is replete with
reports of false positive iodine-131
(131I) uptake in many parts of the body in
patients with a history of thyroid cancer, thus simulating metastatic
disease. The occurrence of lingual thyroid in patients with
thyroid cancer is also a rarity. We present a case of an elderly woman
with papillary thyroid cancer who had a positive
131I uptake at the level of the chin that was
presumed to be metastatic disease. However, the histopathological
diagnosis showed normal lingual thyroid tissue.
 |
Case presentation
|
---|
A 72-yr-old woman presented in 1996 for further evaluation of
enlargement of the right lobe of her thyroid that had been present
since 1990. Approximately 30 yr before presentation, the patient had
undergone left thyroid lobectomy for a benign nodule. In 1990, the
patient developed enlargement of the right lobe. She was started on
T4 suppression therapy, but over the next
6 years, an increase in size of the right lobe was noted. There was no
history of radiation exposure to the neck, and the rest of her past
medical history and family history was unremarkable. On examination in
1996, the right lobe was 7 x 4 cm in diameter. The left lobe was
absent. Fine-needle aspiration biopsy of the right lobe revealed
changes suggestive of papillary thyroid cancer. A noncontrast computed
tomography (CT) scan confirmed the presence of the mass. One of the
sections of the CT scan revealed a hypodense area at the base of the
tongue that was considered to be an artifact. In July 1996, the patient
underwent a right lobectomy. Pathologic examination revealed the
presence of a 4.5-cm papillary thyroid cancer, without nodal
involvement or extrathyroidal extension. After withdrawal from
T4, a diagnostic radioiodine scan showed two
distinct areas of uptake in the neck (Fig. 1A
). Along with uptake in the thyroid bed
(0.22%), there was also an area of greater uptake at the level of the
chin (1.38%). Following the scan, in November 1996, the patient
underwent ablation therapy with 105 mCi
131I. At that time, her serum TSH was 38.9 mU/L
and thyroglobulin (Tg) was 72.1 ng/mL. A post-therapy scan again showed
two distinct regions of uptake in the neck (Fig. 1
, B and C), with no
evidence of distant metastases. The patient was started on
levothyroxine suppression therapy.

View larger version (73K):
[in this window]
[in a new window]
|
Figure 1. A, The first diagnostic scan illustrating
two distinct regions of 131I uptake: the thyroid bed and at
the level of the chin. B, The post-therapy scan confirming the two
distinct regions of 131I uptake. C, Magnified view of the
head and neck area.
|
|
On withdrawal from T4 in June 1997, her serum TSH
was 48.5 mU/L and Tg was 34.6 ng/mL. A second diagnostic scan was
performed, which now demonstrated absent uptake in the thyroid bed, but
significant residual uptake at the level of the chin, thought to be
consistent with a metastasis at the base of the tongue (Fig. 2A
). The patient was treated with 111 mCi
131I, and a post-therapy scan again failed to
show any distant metastatic disease (Fig. 2B
). In January 1998,
following T4 withdrawal, her TSH was 78.4 mU/L
and Tg was 17.5 ng/mL. A third diagnostic scan still showed an abnormal
area of radioiodine accumulation at the level of the chin, with a
72-h uptake of 0.14%. The patient was not treated.

View larger version (133K):
[in this window]
[in a new window]
|
Figure 2. A, The second diagnostic scan showing no
uptake in the thyroid bed but significant uptake at the level of the
chin. B, The post-therapy scan confirming the uptake at the level of
the chin. No distant metastatic foci were seen.
|
|
In May 1999, scanning with recombinant human TSH (rhTSH) was performed.
After two injections of rhTSH, her serum TSH increased to 31 mU/L and
Tg to 10.4 ng/mL. A diagnostic scan again showed uptake at the level of
the chin, which was 0.02% at 72 h. In July 1999, during
withdrawal from thyroid hormone, her TSH was 75 mU/L and Tg 17.7 ng/mL.
She was treated for a third time with 147.5 mCi
131I. A post-therapy scan again showed the
abnormal area. A contrast enhanced CT scan of the neck, performed to
further evaluate this abnormal uptake, showed a 1 x 1.2-cm
enhancing mass at the base of the tongue (Fig. 3
). The patient was then referred for an
otolaryngologic evaluation. The lesion was not visualized by indirect
laryngoscopy, but laryngoscopy under general anesthesia revealed a
2 x 2-cm well circumscribed firm white mass at the base of the
tongue. An incisional biopsy specimen had a cut surface that was tan
and smooth. There was no adherent skeletal muscle. Histologic
examination showed numerous follicular structures embedded in a pink
hyalinized stroma (Fig. 4A
). The
follicles were filled with pink colloid-like material and lined by
uniformly spaced cuboidal epithelial cells. These cells had round
uniform nuclei that lacked enlargement, grooves, optical clearing, or
inclusions. An immunohistochemical stain for Tg (prediluted;
Immunotech, San Jose, CA) demonstrated strong and
diffuse staining of the epithelial cells and the intrafollicular
colloid material (Fig. 4B
). On T4 suppression,
her serum TSH was 0.05 mU/L, free T4 was 1.8
ng/dL, T3 was 1.07 ng/mL, and Tg was less than
1.0 ng/mL.

View larger version (105K):
[in this window]
[in a new window]
|
Figure 3. A contrast enhanced CT scan of the neck
showing a 1 x 1.2-cm enhancing mass at the base of the tongue.
|
|

View larger version (132K):
[in this window]
[in a new window]
|
Figure 4. Lingual thyroid tissue. a, The thyroid
follicles are filled with colloid material and lined by a cuboidal
epithelium without atypia (hematoxylin and eosin, x200). b,
Immunohistochemical stain for Tg shows strong staining of the
follicular epithelium and the intrafollicular colloid (Tg immunostain,
x200).
|
|
In May 2000, scanning with rhTSH was performed. After two injections of
rhTSH, her serum TSH increased to 174 mU/L and Tg to 6.2 ng/mL. The
scan again showed uptake at the level of the chin, consistent with the
uptake in the lingual thyroid.
 |
Discussion
|
---|
In this case report, we describe a patient with papillary
thyroid cancer who had a lingual thyroid masquerading as a metastatic
focus. Although the endocrine literature is replete with false positive
131I uptake simulating metastatic disease, only
one published report has described lingual thyroid as the cause of
false positive scan (1). However, in that patient, a
biopsy was not performed and, therefore, histological evidence is
lacking. To the best of our knowledge, the present case is the first
histologically proven lingual thyroid simulating a metastatic focus in
a patient with thyroid cancer.
False positive diagnostic 131I scans are due to
uptake in many parts of the body and can be divided into physiologic
and pathologic tracer uptake (2, 3). Physiologic uptake is
usually seen in salivary glands, nasal mucosa, salivary secretions
(tracheostomy site), lactating breast, liver, gastric mucosa, small and
large intestine, urinary bladder, and in patients with hyperhiderosis
(due to secretion of the tracer in sweat). Causes of pathologic uptake
in the head and neck region are few. Meningiomas, dacrocystitis,
prosthetic eye, sinusitis, dental disease (dental caries,
periodontitis, pulpitis, periapical granuloma, etc.),
sialadenitis, Warthins tumor, and hypertrophied thyroglossal duct
remnant have all been reported as masquerading thyroid cancer
metastasis.
Lingual thyroid is the most common location for ectopic thyroid tissue,
accounting for 90% of the cases. Lingual thyroid is defined as the
presence of thyroid tissue in the midline at the base of the tongue
anywhere between the circumvallate papillae and the epiglottis. The
prevalence of lingual thyroid is 1 in 100,000, and it is more common in
women, with a female to male ratio ranging between 3:1 to 7:1.
Embryologically, the thyroid originates at the foramen cecum, which is
located at the junction of the anterior two thirds with the posterior
one third of the tongue. Between the third to seventh week of
gestation, the gland descends to form the normal thyroid gland in the
pretracheal position (4). A failure to migrate normally
may leave part or all of the thyroid tissue at the base of the tongue,
or at any other position along the thyroglossal tract. The reported age
at diagnosis of lingual thyroid has ranged from birth to 83 yr of age,
with the mean of 40.5 yr. In 7075% of patients with lingual thyroid,
there is no eutopic thyroid tissue present in the pretracheal position
(5).
Differentiation between lingual thyroid tissue and metastatic thyroid
cancer may be difficult. On inspection, the surface of the lingual
thyroid may be smooth or irregular. Occasionally, large blood vessels
are present on the surface of lingual thyroid tissue, predisposing to
ulceration and hemorrhage (6). Most detailed histological
studies have shown that lingual thyroid tissue characteristically has
an incomplete or poorly defined capsule. Therefore, benign lingual
thyroid tissue may appear malignant due to what appears to be the
invasion into the muscle, but this only signifies a defect in the
capsule, resulting in intermingling of the glandular and the muscular
elements (7). In addition, a variable amount of
inflammatory infiltrate is not uncommon in lingual thyroid glands
(8). The use of Tg immunoperoxidase staining may help in
the diagnosis and characterization of the lingual mass, especially in
patients who have received radioactive iodine therapy (as in our case),
which distorts the histological architecture of the tissue. The use of
Tg staining can also help in determining the etiology of a lingual mass
of uncertain origin.
Interestingly, a kinetic analysis of iodine turnover in lingual thyroid
tissue showed a biological half-life of 1.3 days compared with 100 days
in the normal thyroid tissue (9). This phenomenon may
explain why the lingual thyroid in the present patient was so resistant
to ablation, compared with the remnant tissue in the thyroid bed. Even
after almost 360 mCi radioiodine, the tissue was still present on a
whole body scan after T4 withdrawal.
Although the present patient clearly had a benign process, cases
of thyroid cancer metastasizing to the oral cavity have been reported.
In one patient, metastatic foci of follicular thyroid cancer were
present on the lower lip and on the dorsum of the tongue
(10). To the best of our knowledge, this is the only case
of thyroid cancer metastasizing to the tongue in the literature. In
another patient, a calcified papillary thyroid cancer was found in the
parapharyngeal space masquerading as a parotid mass (11).
Hence, it is clear that metastases to the base of the tongue are a rare
event. Therefore, if 131I uptake is seen in this
area, lingual thyroid is the most likely explanation, even in a patient
with known thyroid cancer. However, if the mass is painful or results
in bleeding, a biopsy should be the next step because papillary
carcinoma in an ectopic lingual thyroid tissue has been reported
(12).
In summary, we describe a patient with papillary thyroid cancer
and concurrent lingual thyroid tissue. When the two areas of distinct
131I uptake were seen in our patient, one in the
thyroid bed and the other at the level of the chin, it was assumed that
the latter corresponded to metastatic thyroid cancer at the base of the
tongue. The patient was treated three times with radioactive iodine
therapy for this lesion. Finally, on biopsy and Tg staining it was
confirmed that this tissue is a normal ectopic lingual thyroid, without
any evidence of malignancy. The reduction in the size of lingual
thyroid following radioactive iodine therapy required much higher doses
of radioiodine than were required to ablate the thyroid bed tissue.
In conclusion, lingual thyroid tissue can masquerade as a
metastasis to the hypopharynx. The possibility of a lingual thyroid
being present should be considered in all patients with a midline area
of radioiodine uptake at the level of the chin, especially if it is
relatively resistant to radioiodine ablation.
Received July 12, 2000.
Revised October 4, 2000.
Accepted October 4, 2000.
 |
References
|
---|
-
Sud AM, Gross MD. 1991 Radioiodine uptake
following thyroidectomy for thyroid cancer. Recurrence or ectopic
tissue? Clin Nucl Med. 16:894897.[Medline]
-
Sutter CW, Masilungan BG, Stadalnik RC. 1995 False-positive results of I-131 whole-body scans in patients with
thyroid cancer. Semin Nucl Med. 25:279282.[Medline]
-
McDougall IR. 1995 Whole-body scintigraphy
with radioiodine-131. A comprehensive list of false-positives with some
examples. Clin Nucl Med. 20:869875.[Medline]
-
Arancibia P, Veliz J, Barria M, Pineda G. 1998 Lingual thyroid: report of three cases. Thyroid. 8:10551057.[Medline]
-
Neinas FW, Gorman CA, Devine KD, Woolner LB. 1973 Lingual thyroid. Clinical characteristics of 15 cases. Ann Intern Med. 79:205210.[Medline]
-
Kansal P, Sakati N, Rifai A, Woodhouse N. 1987 Lingual thyroid. Diagnosis and treatment. Arch Intern Med. 147:20462048.[Abstract]
-
Jones P. 1961 Autotransplantation in lingual
ectopia of the thyroid gland: review of the literature and report of a
successful case. Arch Dis Child. 36:164170.[Medline]
-
Ward GE, Cantrell JR, Allan WB. 1911 The surgical
treatment of lingual thyroid. Ann Surg. 139:536544.
-
Ramos-Gabatin A, Pretorius HT. 1985 Radionuclide
turnover studies on ectopic thyroid glandscase report and survey of
the literature. J Nucl Med. 26:258262.[Abstract]
-
Whitaker B, Robinson K, Hewan-Lowe K, Budnick S. 1993 Thyroid metastasis to the oral soft tissues: case report of a
diagnostic dilemma. J Oral Maxillofac Surg. 51:588593.[Medline]
-
Carter LC, Uthman A, Drinnan AJ, Loree TR. 1997 Diagnostic dilemma involving calcification in the parapharyngeal space:
metastatic thyroid carcinoma masquerading as a deep lobe parotid mass. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 84:697702.[Medline]
-
Casella A, Pisano R, Navarro Cuellar C, Llopis P,
Mallagray R, Lavorgna G. 1999 Papillary carcinoma of the base of
the tongue. Case clinic. Minerva Stomatol. 48:535538.[Medline]