LINGUAL THYROID: A Case Report
LE VAN TAI, MD - NGUYEN THIEN HUNG, MD - PHAN THANH HAI, MD
MEDIC Medical Center
Ho Chi Minh City, Vietnam
We report one case of a 36 year-old female patient who have presented with symptom of dysphonia (hot potato speech) for 7 months due to an abnormal mass at the base of the tongue. Thyroid function tests were normal (TSH ultrasensitive = 4.65microUI/mL; T3 =1.19ng/mL; T4 free = 0.96ng/dL).
,Ultrasound detected no thyroid tissue at the usual site of the neck but only a small cyst on the right side. At the base of the tongue, the mass with 3.8x3.0cm in size appeared hypoechoic and hypovascular on color Doppler ultrasound and was suspected to be ectopic thyroid tissue.
Then Tc99m- pertechnetate scanning confirmed thyroid tissue at the base of tongue and there was no uptake in the normal location.
Because the patient refused surgery, a hormonal therapy has been indicated.
Lingual thyroid is thyroid tissue which is found in the foramen cecum area of the tongue. Approximately over 400 cases have been reported in the literature (Van der Waal et al., 1986) but our case was examined by color ultrasound and other imaging modality (radionuclide scanning).
The patient was an unmarried 36 year-old female who has had symptom of dysphonia (hot potato speech ) for 7 months. Examination of the throat showed an abnormal mass at the base of the tongue (Fig1). She had neither symptoms of hyperthyroidism nor hypothyroidism and no past history of any special diseases.
We used Toshiba colour ultrasound machine (Eccocee) with 7.5MHz linear probe. In the process of examination, we did not find thyroid tissue at the normal site (Fig2) except a small cyst with regular contour and no sign of vascular flow was found on the right side. At the base of tongue, in coronal section through the mouth floor, there was a solid, hypoechoic mass about 3,8x3,0cm in size with regular border but hypovascularity on color Doppler. Because of the absence of normal thyroid tissue, we suspected that this mass was very likely to be ectopic thyroid tissue (Fig3).
Tc99m - pertechnetate scanning showed there was increased uptake at the base of tongue where corresponds with the location of the mass, and there was no uptake at the normal thyroid location. And radioactive iodine uptake ( RAIU ) at 6 hours or at 24 hours was very low (5%) (Fig5). However, thyroid function tests were normal (TSH ultrasensitive = 4.65microUI/mL; T3 =1.19ng/mL; T4 free = 0.96ng/dL).
So, by ultrasound and scintigraphy, we think that this is the case of ectopic thyroid gland at the base of tongue or one lingual thyroid case. Up to now, there has not had unique management for this case yet. For the chief complaint of our patient was dysphonia and she refused surgery, we indicated hormonal suppressive therapy with levothyroxin (50mcgr/day per os) with the hope that the mass will be shrunk and dysphonia relieved.
We have a lingual thyroid case of 36 year-old female patient which is proved by scintigraphy of technetium and radioactive 131I. But we do not know why she has dysphonia only for 7 months and the nature of a cyst at right side of the neck, because a lingual thyroid is rarely associated with the presence of a normally positioned thyroid gland (6).
According to Roddie ME and Kreel L (10 ), ectopic thyroid tissue may occur anywhere along the line of the thyroglossal duct, and when this occurs there is usually no functioning thyroid tissue in the normal site.
In children, Lambert GH (9) said that ectopic thyroid tissue may provide thyroid hormones for many years or may fail in early childhood. Affected children come to clinic because of a growing mass at the base of the tongue or in the midline of the neck. Occasionally, ectopic thyroid is associated with thyroglossal duct cysts.
Ectopic thyroid tissue is usually in women (with clinical manifestations are a rounded, smooth, mucosa-covered mass of variable size in the base of the tongue and rich vascularity) and is influenced by hormones (Van der Waal et al.) (12). The age of onset is in the range of 20-30 years old. The symptoms are dysphagia, dyspnea, and dysphonia (hot potato speech). In some cases the lingual thyroid tissue is the only functioning thyroid tissue. The histopathology of lingual thyroid is similar to normal thyroid. The risk of malignant degeneration of a lingual thyroid is small.
Some patient cases show hypothyroidism or hyperthyroidism but the latter is exceptional.
Diagnosis is by physical examination, thyroid function tests and scintigraphy with technetium or radioactive iodine to find the functional thyroid tissue outside the base of the tongue. Because of hemorrhage and infection, biopsy should rarely be performed. Although with the high resolution 7.5MHz linear probe, the role of ultrasound is limited because ultrasound findings are non specific besides its avantages: sensitive, accessible, and low cost.
Other congenital tumors occurring around of the tongue include ranulas, hemangiomas, cystic hygromas, fibromas, ectopic brain tissue, and hamartomas.
Treatment is not necessary and depends on the complaints of the lingual thyroid patients.
Three treatment options are available. First, using thyroid hormones for shrinking the mass. Second, radioactive 131iodine may kill the thyroid tissue in the base of the tongue. The third modality of treatment is surgery. The surgical indications are dysphagia, dysphonia, dyspnea, repeated or severe hemorrhage, uncontrolled hyperthyroidism, degeneration with necrosis, and suspected malignant transformation. Because of malignant transformation, excision is recommended in male patient over 30 years old. Autoimplantation of the ectopic thyroid is reported (9), but is not recommended because of the increased risk of malignant transformation.
We present a case of lingual thyroid of 36 year-old female patient with dysphonia for 7 months and no thyroid tissue at normal site. The results of color ultrasound, scintigraphy with technetium and radioactive 131iodine are documented. Because the woman denied surgical excision so a hormonal treatment is made with levothyroxin 50mcgr/day per os.
Fig 1: and Fig.1b: Lingual thyroid: pink structure at the base of the tongue.
Fig 2: Transversal section of ultrasound scan of the neck: a small cyst on the right side.
Fig.3: Transversal section of ultrasound scan of the mouth floor: a solid echo poor mass at the right side of the base of the tongue.
Fig.4: Technetium scintigraphy: high level of concentration of 99m Tc - pertechnetate at the base of the tongue more than at the salivery glands, and no sign of concentration of technetium at the normal site of the thyroid.
Fig.5: Radioactive Iodine Uptake: Low uptake at 5 hours and 24 hours.
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