Surgery Today

, Volume 43, Issue 8, pp 937–941

Hydatid cyst of the thyroid gland: report of three cases

Authors

  • Mehmet Yilmaz
    • Division of Liver Transplantation, Department of SurgeryInonu University Faculty of Medicine
    • Division of Liver Transplantation, Department of SurgeryInonu University Faculty of Medicine
  • Gokhan Sogutlu
    • Department of SurgeryMalatya Park Hospital
  • Ebru Arabaci
    • Department of PathologyInonu University Faculty of Medicine
  • Cuneyt Kayaalp
    • Division of Liver Transplantation, Department of SurgeryInonu University Faculty of Medicine
Case Report

DOI: 10.1007/s00595-012-0269-7

Cite this article as:
Yilmaz, M., Akbulut, S., Sogutlu, G. et al. Surg Today (2013) 43: 937. doi:10.1007/s00595-012-0269-7

Abstract

Cystic Echinococcosis is a parasitic infestation that is distributed world-wide. It may be found in nearly any part of the body, most often in the liver and the lungs, but occasionally in other structures such as the thyroid gland. The present study reports three cases of hydatid cysts of the thyroid gland, in patient ranging from 18 to 25 years of age. Two patients had concomitant hydatid disease involving organs other than the thyroid gland (secondary disease), and one had, sole, involvement of the thyroid gland itself (primary disease). Moreover, an occult papillary thyroid carcinoma was detected incidentally in one case, involving the unilateral thyroid lobe as the hydatid cyst. While several surgical procedures including left lobectomy and isthmectomy were undertaken in one patient, two patients underwent total thyroidectomy. No disease recurrence was observed in any of the three patients during the postoperative follow-up period. No study reporting the concomitance of hydatid cyst and neoplasia of the thyroid gland has been previously published. This concomitance indicates the importance of the differential diagnosis of lesions characterized by calcifications in the thyroid gland, especially in endemic regions.

Keywords

Hydatid cystUnusual locationThyroidDifferential diagnosis

Introduction

Echinococcal disease, also known as hydatid disease, is common in societies in which agriculture and domesticated animals are common, and it continues to be a serious public health problem in many countries, including Turkey. Echinococcal disease is caused by infection from the metacestode stage of Echinococcus tapeworms of the family Taeniidae. Four species of Echinococcus cause infection in humans; E. granulosus and E. alveolaris are the most common, causing cystic echinococcosis and alveolar echinococcosis, respectively. The primary carriers are dogs and wolves, while the intermediate hosts are typically sheep, cattle, and deer. Humans, who are accidental hosts and do not play a role in the biological cycle, are infected by ingesting ova from soil or water contaminated by the feces of dogs [1].

Hydatid disease may develop in any organ of the body, most frequently in the liver and lung, but occasionally can affect other organs and regions [19]. The thyroid gland is very rarely affected by hydatid disease even in countries where the disease is endemic [2, 6]. Echinococcus granulosus can bypass the liver and lungs and settle in the thyroid gland via the systemic circulation, which enables it to reach the thyroid by way of first the carotids and then the thyroid arteries. A high circulatory flow rate in the thyroid gland may play an important role in the development of the thyroid hydatid cyst [2]. The mechanism by which the relatively high thyroid blood flow relates to the disproportionately low incidence of thyroid cyst disease is unknown, but one theory implicates the relatively small caliber of the thyroid arteries together with their position at a right angle to the carotids, an anatomical arrangement that is thought to offer the thyroid gland some measure of protection against the invading parasite [24]. This report presents three original cases of thyroid hydatid cysts. One had disseminated hydatid disease and the thyroid was one of the disseminated organs. Another case was exciting because of an allergic reaction during surgical dissection. The last one had a combination of thyroid hydatid cyst and thyroid papillary carcinoma.

Case reports

Case-1

An 18-year-old male patient was admitted to the outpatient polyclinic with a swelling in the left anterolateral side of the neck. The patient had been living in a rural area in the Eastern part of Turkey and had frequent direct contact with sheep, dogs, and other farm animals. He had a previous history of admission to the hospital with the same complaint 3 years earlier; ultrasonography and thoracoabdominal computed tomography (CT) performed at that time had detected lesions in the liver, left kidney, right lung, right-sided anterior abdominal wall and left lobe of the thyroid gland, which were compatible with hydatid cysts (Fig. 1). The indirect hemagglutination test (IHA) carried out for echinococcus was positive. Thyroid function tests, complete blood count, serum electrolytes, eosinophil count, serum biochemistry and urinalysis were within normal limits. Tc-99 m pertechnetate scintigraphy was performed 15 min after the intravenous injection of 5 mCi. The scan showed two respective cold regions in the left lobe and the isthmus. The patient had not been advised to undergo a surgical removal at that time due to disseminated hydatidosis and, instead, had been placed on mebendazole therapy for 2 months. Computed tomography images acquired following the treatment had revealed involution of the mass in the left thyroid lobe, along with regression of the cysts (Fig. 2). Thereafter, he was readmitted on follow-up with complaints of enlargement of the masses in his neck and abdominal wall, as well as dysphagia. The physical examination performed on his second admission revealed a palpable solitary nodule 3 cm in diameter in the anterior neck region compatible with the left thyroid lobe. Three 3.5 cm lesions compatible with hydatid cysts were detected by both thyroid ultrasonography and neck computed tomography (Fig. 3). In addition, the thoracoabdominal images revealed lesions suggestive of hydatid cysts in the liver, lung and anterior abdominal wall. A surgical procedure was planned for the patient, following 14 days of albendazole treatment at 400 mg/day. Left lobectomy and isthmectomy were performed through a collar incision under general anesthesia, along with en bloc excision of the cystic mass located in the anterior abdominal wall. Histopathological evaluation of both specimens was consistent with hydatid cysticosis. The patient continued albendazole therapy at the same dose regimen for 2 months postoperatively. No recurrence was evident in the thyroid during the 36-month postoperative period.
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Fig. 1

Contrast enhanced CT of the neck shows a sharp and thin walled cystic mass with fluid content in the left lobe of the thyroid

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Fig. 2

The thyroidal cyst showed diffuse membrane detachment indicating hydatid disease and regression in size after two months of medical treatment

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Fig. 3

The cystic mass that measured 35 mm in the left lobe of the thyroid, pushing the trachea to the left

Case-2

A 25-year-old female patient was admitted to the outpatient polyclinic with a pain in her neck. The patient had been living in an urban area in the Southeastern region of Turkey and lacked any direct contact with animals. The physical examination revealed hyperplasia of both thyroid lobes, and subsequent thyroid ultrasonography detected multiple lesions, with the largest one measuring 2 cm in diameter, expanding across both thyroid lobes. Calcification was evident in the posterior wall of the cystic lesion in the left lobe. Thyroid function tests and other biochemical blood parameters were within the normal range. Fine needle aspiration cytology (FNAC) was advised, but the patient preferred to undergo surgical excision instead. A collar incision revealed an exophytic cystic lesion localized at the junction of the left lobe and the isthmus. A sizable number of daughter vesicles were identified following iatrogenic dissection into the cystic cavity (Fig. 4). The surgical procedure was complicated by anaphylactoid reactions (hypotension, bradycardia, rash) developing during manipulation of the cyst. A constellation of medications including steroid and antihistaminic agents, as well as adrenaline, was administered to the patient. The procedure was completed following bilateral total thyroidectomy. The pathological evaluation was consistent with multinodular goiter and hydatid cyst in the left thyroid lobe. Albendazole therapy was instituted immediately post-operatively, at a dosage of 400 mg daily for 6 weeks. There appeared to be no other focus for hydatid cysts on thoracoabdominal computed tomography performed in the postoperative period, and an indirect hemagglutination test carried out on blood came back negative. No recurrence of the lesions in the thyroid was detected over a 14-month period postoperatively.
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Fig. 4

Intraoperative appearance of the thyroid gland. The hydatid cyst ruptured accidentally on manipulation

Case-3

A 21-year-old male patient was admitted to the outpatient polyclinic with swelling in the neck. The patient’s medical history was negative for any systemic disease; moreover, the patient confessed that he had not been admitted to any hospital until that time. He was involved in farming in a rural area in the Eastern region of Turkey. The physical examination revealed no pathological finding other than thyroid multinodularity, most prominent in the left lobe, on cervical examination. Thyroid function tests and other biochemical blood parameters were within normal ranges. Thyroid ultrasonography detected a number of nodules, with the largest one measuring 2 × 2 cm in diameter, in the right lobe. In addition, the left lobe contained two nodules characterized by calcifications in the posterior wall, one measuring 3 ×2 cm in diameter and one measuring 1 × 0.5 cm in diameter. Bilateral total thyroidectomy was undertaken in the patient, anticipating a malignancy. Pathological examination confirmed the presence of hydatid cyst in the left lobe, along with occult papillary thyroid carcinoma in a smaller area (Fig. 5). Abdominal ultrasonography performed in the postoperative period revealed a lesion compatible with calcified hydatid cyst in the right hepatic lobe. Albendazole treatment was implemented for 6 weeks following surgery Fig. 6).
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Fig. 5

Cyst wall and membranous eosinophilic cuticles of hydatid cyst (HE, ×40)

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Fig. 6

Papillary microcarcinoma focus (right side) surrounded by fibrocollagenous wall of the hydatid cyst (HE, ×40)

Discussion

Hydatid disease is a parasitic infection with worldwide distribution, especially in sheep- and cattle-rearing regions of Australia, South America, the Middle East, South Africa, Eastern Europe, and the Mediterranean countries. The most frequent site of hydatid cystic disease is the liver because it is the first and largest filter of invading organisms migrating from the intestine via the portal stream. Parasite that manage to migrate through the hepatic filter can then enter the systemic circulation and settle in the lungs or, rarely, in other organs of the body including the spleen, brain, heart, bones, muscles, kidney, pancreas, retroperitoneum, breast, and thyroid gland [1, 5].

The thyroid gland is an extremely rare site of hydatid disease, even in countries with a high incidence of echinococcosis such as Turkey [3, 6, 7]. The incidence of thyroid gland involvement varies from 0 to 3.4 % in the literature [5, 9]. The parasitic embryo can enter the systemic circulation and lodge in the thyroid gland after either bypassing or passing through the hepatic microcirculation [2, 68]. Hydatid disease of the thyroid is divided into primary and secondary forms. The primary form refers to thyroid hydatid cysticosis diagnosed by clinical, radiologic and histopathological means, with no evidence of extrathyroidal hydatid disease. The secondary form is associated with additional hydatid disease of the liver, pulmonary system, or other organs. Hydatid cyst of the thyroid is generally the primary focus of the infestation; only a few patients are reported to have had secondary hydatid cysts in the liver, lung or other organ besides the thyroid [3, 6, 8]. Two of the cases reported in this study involved secondary hydatid disease, while one demonstrated primary hydatid disease.

Thyroid gland hydatid disease usually presents as a solitary cyst, and is normally a cold lesion according to radioactive iodine scanning of the thyroid. Hydatid cysts of the thyroid appear to be mostly asymptomatic until the size causes mechanical problems, leading to dyspnea, hoarseness of voice and dysphagia [4, 68]. These symptoms and signs stemming from an increase in the size of the cyst and impingement of the cyst on the surrounding tissues are likely to be frequently confused with those of thyroid cancers [6].

The complications associated with thyroid hydatid disease include anaphylaxis caused by a spontaneous or iatrogenic rupture, pyogenic abscess formation, secondary infections, impingement on surrounding structures, and spillage of the cystic content into the tracheal lumen secondary to a rupture of the cystic wall [2].

Goiter is the most common endocrine disorder requiring surgical management, particularly in areas where iodine deficiency is prevalent [6, 10]. Estimates show that approximately 30 % of people in Turkey suffer from goiter [10]. Moreover, such disease as hydatid disease, which are among those severely affecting public health, remain endemic in the Eastern, Southern and Central Anatolia regions of Turkey. Therefore, hydatid disease should be included in the differential diagnoses of any patient evaluated for nodular goiter.

A medical publication review, performed by entering “thyroid”, “echinococcosis”, “hydatid cyst”, “hydatid disease” etc. into PubMed, Google Scholar and Medline databases, identified more than 60 published case reports of thyroid hydatid cysts. There was no published study reporting the concomitance of hydatid cyst and neoplasia either within one lobe or in contralateral lobes of the thyroid gland. So, the third case reported in this review is evidently the first known case of this phenomenon. However, the concomitance of a hydatid cyst and papillary carcinoma either within one lobe or in contralateral lobe of the thyroid was thought to be absolutely incidental. This concomitance indicates that more meticulous attention should be given to the differential diagnosis of the thyroid diseases characterized by calcification.

Diagnosis of hydatid disease is made primarily by patient history, physical examination, imaging modalities, serologic tests, and fine needle aspiration cytology (FNAC). Imaging modalities usually include ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasonography is highly efficient in detecting germinal vesicles in cystic lesions, which is important for a preoperative diagnosis of hydatidosis; CT-scan and MRI are often complementary diagnostic tools [2, 9]. Serological tests for hydatidosis at a clinician’s disposal include indirect hemagglutination (IHA), latex agglutination(LAT), Enzyme-linked immunosorbent assay (ELISA), and immune electrophoresis, but these have drawbacks of low diagnostic sensitivity and specificity so, therefore, have only limited use [6, 9]. Fine needle aspiration cytology (FNAC) is universally accepted as part of the clinical workup in cases of a single thyroid nodule. Although there is only one report in the literature mentioning allergic reaction after FNAC [3], it is not recommended, due to the risk of spreading cyst fluid or causing an anaphylactic reaction. Therefore, FNAC should be avoided when hydatid cyst of the thyroid is included in the differential diagnoses [7].

The treatment of choice for hydatid disease of the thyroid is surgical excision, as is the case elsewhere in the body, and radical cystic excision should be the goal of the procedure whenever possible [7, 8]. However, the authors also recommend subtotal thyroidectomy, especially when the cyst is small and confined to the thyroid lobe. Special care should be taken not to rupture the cyst during surgery because of the risk of disseminating the infestation or causing anaphylaxis. The antiparasitic agents, mebendazole, albendazole and praziquantel, can be used as the sole treatment for hydatid disease, or they can be used in conjunction with surgery to kill the live parasites pre-operatively and prevent any possible contamination caused by the spillage of cyst contents during the operation. In addition, antiparasitic agents are also necessary to avoid recurrence.

In conclusion, despite the rarity of hydatid disease in the thyroid gland, this diagnosis should not be overlooked, especially if the patient has hydatid cysts elsewhere in the body and/or has visited an endemic area.

Acknowledgments

Authors would like to thank the Editor of Journal of Inonu University Medical Faculty for allowing the use of first three figures.

Conflict of interest

The authors declare that there is no conflict of interest.

Copyright information

© Springer 2012