|Year : 2013 | Volume
| Issue : 2 | Page : 145-147
Papillary thyroid micro carcinoma masquerading as branchial cleft cyst
Rashmi Krishnappa, Aarathi Rau, Usha Ravi Kumar, Mekala Lakshminarayanan
Department of Pathology, MS Ramaiah Medical College, Bangalore, Karnataka, India
|Date of Web Publication||13-Dec-2013|
#50/3, 1st Cross, 1st Main, Nanjappa Layout, Vidyaranyapura, Bangalore - 560 097, Karnataka
Source of Support: None, Conflict of Interest: None
Papillary thyroid microcarcinomas (PTMC) have excellent prognosis, although a few may present with metastasis to cervical lymphnodes. We present one such case of PTMC presenting as a left neck cyst without evidence of palpable primary thyroid nodule either clinically or on imaging. On histopathological examination of the excised cyst and subsequent total thyroidectomy, a final diagnosis of PTMC with cervical lymphnode metastasis undergoing cystic degeneration was given. We conclude that PTMC may also present as lateral neck cyst with an occult primary in thyroid gland.
Keywords: Branchial cleft cyst, histopathological examination, metastasis, papillary thyroid microcarcinoma
|How to cite this article:|
Krishnappa R, Rau A, Kumar UR, Lakshminarayanan M. Papillary thyroid micro carcinoma masquerading as branchial cleft cyst. Arch Med Health Sci 2013;1:145-7
|How to cite this URL:|
Krishnappa R, Rau A, Kumar UR, Lakshminarayanan M. Papillary thyroid micro carcinoma masquerading as branchial cleft cyst. Arch Med Health Sci [serial online] 2013 [cited 2020 Feb 21];1:145-7. Available from: http://www.amhsjournal.org/text.asp?2013/1/2/145/123029
| Introduction|| |
Lateral neck cysts may be benign or malignant. The malignant neck cysts are usually metastatic squamous cell carcinoma undergoing cystic change from oropharygeal region. The common benign cysts are branchial cleft cyst, epidermoid cyst, and cystic hygroma.  The branchial cleft cysts are congenital cyst arising in lateral neck due to failure of obliteration of second branchial arches. These cysts are usually lined by stratified squamous epithelium and occasionally are reported to have ectopic thyroid tissue. There are very few cases in literature describing papillary carcinoma arising from these ectopic thyroid tissues. , Frequently, papillary thyroid carcinoma (PTC) presents as occult malignancy with lateral neck cyst. However, it is very rare to see papillary microcarcinomas (PTMC) (size less than 1 cm) to present only as the lateral neck metastasis.  Thus, when papillary carcinoma is detected in lateral neck cyst, this leads to a diagnostic dilemma whether it is cystic change in a lymphnode due to metastasis or primary tumor arising in the thyroid lining of a branchial cleft cyst.
| Case Report|| |
A 55-year-old male farmer visited the surgical outpatient with complaints of mass in left side of neck of three years duration. It started as a small swelling measuring 2 × 2 cm and progressed gradually to attain the presenting size of 12 × 10 cm. He did not complain of dysphagia or neck pain. The initial ultrasound (US) examination showed a well encapsulated cystic lesion measuring 80 × 62 × 26 mm with internal echoes, attached lateral to left carotid vessel. The strap muscles of left neck and adjacent lymph nodes were normal. The cytology of the cyst fluid showed cyst macrophages, based on which a diagnosis branchial cleft cyst was offered. The patient underwent excision of the cyst. The histopathological examination (HPE) of excised cyst showed a unilocular cyst lined by cuboidal to flattened epithelium with lymphoid follicles and papillary thyroid carcinoma with characteristic nuclear features and psamomma bodies in the cyst wall [Figure 1], [Figure 2], [Figure 3]. A diagnosis of metastatic papillary thyroid carcinoma with cystic degeneration was offered and advised to investigate for the primary thyroid lesion. Computerized tomography (CT) imaging showed a few enlarged left cervical lymph nodes in neck. Subsequently, the patient underwent total thyroidectomy with left cervical lymph node dissection. HPE of thyroid showed papillary thyroid microcarcinoma measuring 6 mm in size with predominance of follicular pattern and typical nuclear features such as 'orphan Annie' nucleus, nuclear grooves, and intranuclear inclusion of papillary carcinoma thyroid [Figure 4]. The neck node dissection showed a single node with metastasis and perinodal spread of the tumor. A final diagnosis of PTMC with metastasis in cervical lymphnode was offered. He did not receive any further treatment and was discharged on tablet eltroxin, shelcal, multivitamins, and regular follow up. The patient is presently asymptomatic, five months after surgery.
|Figure 1: Cyst wall lined by columnar to cuboidal cells resting on fibrocollagenous wall. (H and E, X40)|
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|Figure 2: Cyst wall lining and adjacent papillary thyroid carcinoma (arrow) (H and E, X40)|
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|Figure 3: Cyst also shows lymphoid follicles, inset shows orphan Annie nucleus|
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|Figure 4: Thyroidectomy specimen showing papillary thyroid microcarcinoma with predominance of follicular pattern. (H and E, X40)|
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| Discussion|| |
PTMC are defined as the papillary thyroid cancer measuring 1 cm or less in maximum diameter. Advances in the imaging modalities have markedly increased the number of patients diagnosed with PTMC. Most PTMC have indolent courses and excellent prognosis.  Though PTC may present as metastatic lateral neck node, ,, there are only few case reports on PTMC presenting as lateral neck cysts.  Some authors think that these cystic lesions with papillary thyroid carcinoma are metastatic spread from a primary occult thyroid carcinoma, which has undergone cystic change, while others propose that it is malignancy arising in ectopic thyroid tissue in the lining of branchial cyst.  This differentiation is important as the metastasis to lateral neck node indicates higher stage and worse prognosis in PTMC.  In our case, the excised cyst had scanty lymphoid follicles along with thyroid tissue showing papillary carcinoma, favoring metastatic PTMC presenting clinically and on imaging as a branchial cleft cyst.
Though PTMC are generally indolent tumors, BRAF mutation and some histopathological parameters are associated with poorer outcome. The histopathological parameters, which are associated with aggressive behavior and poorer outcome according to various studies, are sub capsular location, extra thyroid extension, mutifocality, cervical lymphnode metastasis, tumor fibrosis, tall cell variant, and follicular pattern.  In our case, the PTMC had predominance of follicular pattern, which is the predictor of worse outcome. Malignant lateral neck cysts are often missed due to longer duration of symptoms and frequent misinterpretation on FNA and ultrasound examination as a benign cyst. Therefore, any neck cyst excised during adult life should undergo histopathological examination.
| Conclusion|| |
Our case highlights that PTMC can present as metastatic lateral neck cyst, closely mimicking a primary papillary carcinoma arising from branchial cleft cyst. The latter can be differentiated by complete histopathological examination of thyroid gland. This discernment is important as the cervical node metastasis indicates higher stage and worse prognostic factor in PTMC. Thus, unusual neck cysts should be excised and subsequently subjected to histopathological examination. Also, any papillary thyroid carcinoma arising in lateral neck cyst should prompt the clinician and surgeon to rule out occult primary thyroid malignancy.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]