------------------------------------------------------------------------------ TITLE: CARCINOMA OF A THYROGLOSSAL DUCT CYST SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds DATE: July 3, 1991 RESIDENT PHYSICIAN: Lane Smith, M.D., FACULTY: Karen Calhoun, M.D. DATABASE ADMINISTRATOR: Melinda McCracken, M.S. ----------------------------------------------------------------------------- "This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion." ABSTRACT: Thyroglossal Duct (TGD) Cysts are a common developmental abnormality. Primary carcinoma can arise in these cysts, but it is a rare occurrence with less then 150 cases reported in the literature. We present a case of an 18 year old female with a papillary carcinoma of her TGD Cyst and a benign thyroid nodule who underwent a Sistrunk excision of her TGD cyst and a hemithyroidectomy. Histopathology of the TGD carcinoma is similar to papillary carcinoma of the thyroid. The literature is reviewed. Treatment of TGD carcinoma includes complete excision of the TGD cyst using a sistrunk procedure. The thyroid is removed if there are suspicious nodules or if the patient has a history of radiation to the neck. Neck dissection is reserved for patients with positive nodes. Patients are placed on suppressive doses of thyroid hormone and long term follow-up is needed. INTRODUCTION Thyroglossal duct (TGD) cysts are twice as common as branchial cleft abnormalities. After lymphadenopathy, they are the second most common neck mass found in children. They are thought to be a persistence of the tract through which the thyroid descends from the base of tongue on the way to its final position in the neck. The persistent tract may then dilate to form a cyst. Often a small amount of thyroid tissue is implanted in the cyst wall. Rarely carcinoma can arise in a TGD cyst. Less then 150 cases of TGD carcinoma have been reported in the literature. We report a case of papillary carcinoma arising in a TGD cyst in a young female who also had a concomitant thyroid nodule. CASE REPORT An 18 year old white female was referred to our clinic for a small right lower lobe thyroid nodule. The patient had no complaints other then occasional fatigue. On physical examination a 1 1/2 by 2 cm right firm thyroid nodule was present as well as a 2 by 2 cm midline neck mass which moved with deglutition. No other masses were found and the base of tongue, as well as the rest of the physical exam was unremarkable. Thyroid function tests were normal. A thyroid ultrasound showed a mixed cystic and solid mass of the right lower lobe of the thyroid. A pertechnetate and I-131 thyroid scan showed a hyperfunctioning "hot" nodule in the right thyroid lobe. No mention was made of any thyroid tissue located in the TGD cyst or in any other locations. A fine needle aspiration (FNA) of the thyroid mass suggested that it was benign. The FNA of the TGD cyst showed a cystic lesion with many psammoma bodies and few atypical epithelial clusters. Because the finding of psammoma bodies, the FNA was repeated on both the thyroid mass and the TGD cyst with the same results. The patient was taken to the operating room where the TGD cyst was removed using the sistrunk procedure. The patient also underwent a right thyroid lobectomy and isthmusectomy. The left thyroid lobe was palpated at the time of the procedure and found to be free of any nodules. The postoperative course was unremarkable. The patient was placed on levothyroxine 0.125mg every day. She has been followed for 12 months with no problems or evidence of recurrence. HISTOPATHOLOGY Microscopic examination of the thyroid showed a benign thyroid adenoma and otherwise normal thyroid tissue (fig. 1.) The thyroid ducts are filled with colloid and these are surrounded by uniform cuboidal cells. The adenoma shows a fibrous capsule with benign appearing cells with slightly more open and larger nuclei. The cells are also more irregular and the ducts smaller. The TGD cyst showed a fibrous cyst wall lined by squamous epithelium (although they can be lined by respiratory epithelium), and normal areas of thyroid nests located in the cyst wall (figs. 2 and 3.) An area of papillary projections with fibromuscular stroma covered by a single or bilayer of cuboidal cells is seen in the cyst wall and lumen (fig. 4.) On higher magnification the cells are seen to be irregular and vesicular filled with large open clear irregular and piled-up nuclei (fig. 5.) Psammoma bodies, which are abnormal areas of calcification, are seen as round lamellar areas which are stained purple (fig. 6.) Psammoma bodies and the papillary projections are highly characteristic of papillary carcinoma (figs. 4 and 6.) The carcinoma did not extend beyond the cyst wall. DISCUSSION Less then 150 cases of carcinoma of the Thyroglossal Duct have been reported. In the past it was thought to be secondary to metastasis from the thyroid gland or from cancer in a pyramidal lobe of the thyroid. It is now generally accepted that TGD carcinoma arises from thyroid tissue remnants located in the cyst itself. While TGD cysts occur most commonly in patients younger then age 20, TGD carcinoma occurs more commonly in older patients with an average age close to 40. It appears to be slightly more common in females. The female to male ratio was 3:2 in 115 cases reported in one review (10), 80% of the cysts were 2-5cm in size. The most common finding is an asymptomatic mass. Other signs and symptoms include a rapidly enlarging mass; a firm, hard or fixed midline mass, dysphagia, dysphonia, or a recent change in the size of the mass, and the presence of lymphadenopathy. A history of irradiation to the neck or mediastinum should arouse suspicion of the possibility of carcinoma. However; most commonly TGD carcinoma is not suspected at the time of surgery. To our knowledge, this is the first reported case in which TGD carcinoma was suspected from the FNA results. Psammoma bodies found in our patient are a prominent feature of papillary carcinoma of the thyroid, and when this is discovered, carcinoma is suspected. These findings were consistent when the FNA was repeated. Papillary carcinoma is the most frequent carcinoma found in a TGD cyst (80%). Other pathological types include follicular or mixed papillary follicular carcinoma (9%), squamous cell carcinoma (5%), adenocarcinoma (2%), anaplastic carcinoma (1%) and other (3%). Metastasis to regional lymph nodes is fairly rare, occurring about 10% of the time. Originally, preferred treatment was wide excision of the TGD cyst and hyoid bone, and a total or near total thyroidectomy. Reasons for this included the multicentric nature of papillary carcinoma and the now disproved theory that TGD carcinoma was due to a metastasis form the thyroid gland. In a frequently quoted study (1), of 35 thyroids removed because of carcinoma in a TCD cyst, only 4 (11%) contained malignant foci. TGD carcinoma is now treated similarly to papillary carcinoma of the thyroid. If the cancer has not invaded beyond the cyst wall, simple complete excision of the cyst using the Sistrunk procedure is adequate. If the carcinoma has extended beyond the cyst wall, wider excision of the surrounding tissue is necessary. Thyroidectomy is recommended only if there a thyroid mass or history of radiation to the neck. As with papillary carcinoma of the thyroid, a modified neck dissection is recommended only in the presence of suspicious or positive nodes. Suppressive therapy is recommended for TGD carcinoma. All patients, whether they receive thyroidectomy or not, should receive adequate doses of thyroid hormone to suppress secretion of TSH. Papillary carcinoma is a slow growing cancer with an indolent course. If the cancer is completely excised, recurrence is rare. The majority of patients with TGD carcinoma have had no recurrences and prognosis is good. However because of the slow growth rate, long term follow-up is recommended. CONCLUSION TGD carcinoma is a relatively rare cancer which arises form thyroid tissue located in the duct itself. Most patients present with an asymptomatic mass. Fine needle aspiration can be useful and may lead to the early suspicion of TGD carcinoma. Treatment consists of complete excision of the TGD cyst and cancer using the Sistrunk procedure. Thyroidectomy is reserved for thyroid involvement or if the patient has a history of radiation to the neck. Neck dissection is performed for those patients with positive nodes, and all patients are placed on suppressive doses of thyroid hormone. Long term follow-up is needed and the prognosis is very good. ---------------------------------------------------------------------------- BIBLIOGRAPHY 1. Bhagavan BS, Rao DRG, Weinberg T: Carcinoma of thyroglossal duct cyst: case reports and review of the literature. Surgery 1970;67:281-292. 2. Fernandez JF, Ordonez NG, Schultz PN, Naguib AS, Hickey RC: Thyroglossal duct carcinoma. Surgery 1991;928-935. 3.Grant CS, Hay ID, Gough IR, Bergstralh EJ, Goellner JR, McConahey WM: Local recurrence in a papillary thyroid carcinoma: Is extent of surgical resection important? Surgery 1988;954-960. 4. Judd ES. Thyroglossal-duct cysts and sinuses. Surg Clin North Am 1963;43:1023-32. 5. McNicoll MP, Hawkins DB, England K, Penny R, Maceri DR: Papillary carcinoma arising in a thyroglossal duct cyst. Otolaryngol Head Neck Surg 1988;99:50-54. 6. Nussbaum M, Buchwald RP, Ribner A, Mori K, Litwig J: Anaplastic carcinoma arising from median ectopic thyroid (thyroglossal duct remnant). Cancer 1981;48:2724-28. 7. Page CP, Kemmerer WT, Haff RC, Mazzaferri EL: Thyroid carcinomas arising in thyroglossal ducts. Ann Surg 1974;180:799- 803. 8. Roses DF, Snively SL, Phelps RG, Cohen N, Blum M: Carcinoma of the thyroglossal duct. Am J Surg 1983;145:266-269. F9. Topf P, Fried MP, Strome M: Vagaries of thyroglossal duct cysts. Laryngoscope 1988;98:740-742. 10. Wiess SD, Orlich CC: Primary papillary carcinoma of a thyroglossal duct cyst: report of a case and literature review. Br J Surg 1991;78:87-89. F11. Zimmerman D, Hay ID, Gough IR, Goellner JR, Ryan JJ, Grant CS, McConahey WM: Papillary thyroid carcinoma in children and adults: long-term follow-up of 1039 patients conservatively treated at one institution during three decades. Surgery 1988;104:1157-66. -------------------------------END---------------------------------------- TEST QUESTIONS - The following test questions are intended to provide proof to accrediting agencies that you have read and understood the entire Grand Rounds element. Your answers should be based on the text of the Grand Rounds element. Answers should be sent by e-mail addressed to fbquinn@utmb.edu. Answers can be sent by U.S Postal Service mail, using a plain sheet of paper on which the Grand Rounds element and the subscriber are fully identified. Correct answers will be transmitted to the subscriber via e-mail. Comments and alternative points of view should be expressed at the end of the list of the subscriber's answers. The University of Texas Medical Branch (UTMB) is accredited by the Accreditation Council For Continuing Medical Education (ACCME) to sponsor continuing medical education for physicians. UTME designates this continuing medical education activity for 1 credit hour in Category 1 of the Physicians's Recognition Award of the American Medical Association. 1. Histopathology of the thyroglossal duct cyst (TGDC) carcinoma is similar to a. medullary carcinoma of the thyroid b. papillary carcinoma of the thyroid c. squamous cell carcinoma of the aerodigestive tract d. follicular carcinoma of the thyroid 2. In the patient with TGDC carcinoma without a history of radiation therapy to the neck and without cervical metastases, treatment consists of a. complete excision of the TGDC using the Sistrunk procedure with suppressive doses of thyroid hormone and longterm followup b. cervical lymphnode dissection c. total thyroidectomy d. radiation therapy 3. In relation to other masses in the neck, TGDC are a. half as common as branchial cleft abnormalities b. the most common neck mass found in children c. frequently found in association with carcinoma of the thyroid d. rarely found to contain carcinomatous elements 4. Thyroglossal duct cysts are thought to arise as a result of a. midline endodermal fusion faults b. metastasis from a carcinoma of the thyroid gland c. a persistence of the tract through which the thyroid descends from the base of the tongue d. hamartomas 5. Which of the following is highly characteristic of papillary carcinoma of the thyroid? a. psammoma bodies and papillary projections b. single layer cuboidal epithelium c. rests of normal thyroid tissue d. squamous or respiratory epithelium lining the cyst 6. Preferred treatment consists in a. wide excision of the TGDC and hyoid bone, and total or near-total excision of the thyroid gland b. simple excision of the cyst c. suppressive treatment with thyroid hormone d. a management plan based on the presence or absence of cyst wall invasion, prior radiation treatment to the neck, and presence absence of cervical lymphnode metastases 7. Suppressive thyroid hormone therapy is recommended for a. cysts containing rests of thyroid tissue b. symptomatic TGD cysts only c. all patients with TGDC carcinoma, to suppress TSH d. patients with cervical lymphnode metastases In order for the sponsors of this CME activity to monitor its usefulness and appropriateness to subscribers, we ask that your supply answers to the following questions concerning the accompanying Grand Rounds Online CME segment: 1. Was the presentation organized in an acceptable manner? yes no opinion no 2. Was the material adequate to your continuing education needs with respect to content? yes no opinion no 3. Was the material appropriate to your clinical practice needs? yes no opinion no 4. Did you feel that the discussants' remarks were responsive to the issues presented in the body of the Grand Rounds segment? yes no opinion no 5. 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