M Urhan, H Cincik, Y Kurt, A Filiz, Y Narin, A Gungor, M Ozata
cystic degeneration, loco-regional spread, papillary thyroid carcinoma
M Urhan, H Cincik, Y Kurt, A Filiz, Y Narin, A Gungor, M Ozata. Papillary Thyroid Carcinoma Metastasis Presenting As A Purely Cystic Lesion In The Neck. The Internet Journal of Nuclear Medicine. 2006 Volume 4 Number 2.
Local lymphatic spread is common in patients with papillary thyroid carcinoma (PTC). Lymph node metastasis to the neck may undergo cystic degeneration which consequently delays the diagnosis and the treatment of underlying thyroid malignancy. In this study we presented 3 PTC patients with a cystic lesion in the neck as the only finding on physical examination. A benign etiology was considered initially, but papillary thyroid cancer was reported after surgical excision of the lesions. All patients underwent thyroid surgery and cervical lymph node dissection subsequently.
Papillary thyroid carcinoma (PTC) is the most common type of endocrine tumors and constitutes approximately 1% of all malignancies. It usually presents as a mass in the thyroid gland but presentation as a lump in the neck is not rare (1). Lymph node metastasis from PTC may rarely undergo cystic transformation (2). It may be indolent and mimic the clinical course of a benign lesion which consequently delays the diagnosis and treatment of the underlying malignancy. In this study we described three PTC patients presenting with a cervical cyst as the initial finding.
The thyroid scan was normal but a hyper-echoic area suspicious for a nodule in the very upper pole of right thyroid lob was reported in ultrasonography (US). Fine needle aspiration was performed from the cystic lesion but no malignancy was reported. Metastatic papillary thyroid carcinoma was detected when the lesion was removed by surgery. The patient underwent a second cervical dissection and total thyroidectomy. The tumor was 1.1 cm in size adjacent to the upper pole of the right thyroid lobe.
All patients were evaluated for persistent thyroid malignancy or any residual thyroid tissue and treated with high dose I-131. Routine laboratory tests including the measurement of serum thyroglobulin/anti-thyroglobulin and a low-dose diagnostic radioiodine whole-body scan were performed in the surveillance period (Figure 3).
A cystic lesion in the neck may prove to be a branchial cyst, teratoma, epidermoid cyst, cystic hygroma, squamous cell carcinoma, dermoid cyst, branchiogenic carcinoma or squamous cell carcinoma of the head and neck. Any underlying malignancy must be considered if the patient is 40 years and older while the diagnosis is usually a congenital cervical cyst in the younger patients (3). Papillary thyroid carcinoma spreads to local lymph nodes in approximately 36% to 40% of the patients and it may rarely present as a cystic cervical lesion (4,5). The cystic metastasis may not progress in size over time and mimic the clinical course of a benign lesion (6). It may be diagnosed as a branchial cyst or cystic hygroma incorrectly thereby the diagnosis and the treatment of the underlying malignancy would be delayed.
Fine needle aspiration biopsy (FNA) is a practical procedure that can be used in evaluating the cervical lumps suspicious for malignancy. However it is of limited importance if performed to semisolid or cystic lesions. The sensitivity and specificity of the procedure can be increased if performed along with US, but, FNA may still fail if the lesion is purely cystic and has no solid part. We had not been able to establish a diagnosis preoperatively with FNA performed to the cystic lesions in 2 of our patients.
The diagnosis of PTC can be even harder in case of an occult primary in the thyroid gland in patients with a cyst in the neck (7). In one of the patients FNA performed to the cervical cyst and the nodule in the thyroid were negative however multi-focal tumor the greatest 3 mm in size were reported histologically. Interestingly a single nodular lesion approximately 15 mm in size was detected in thyroid gland of the same patient.
Thyroid papillary carcinoma may rarely originate from thyroglossal duct remnants located in the midline of the neck. It is seldom diagnosed preoperatively because the majority of the lesions are purely cystic (8). The median age is usually the fourth decade, but we presented a 25-year-old female in our study. Ozturk et al. has also presented an 11-year old boy with papillary carcinoma arising in a thyroglossal duct cyst (13). The primary tumor had already been detected with FNA preoperatively in our patient and a single operation including cervical dissection was performed. A yellowish-gray solid tumor 1 cm in size was reported histologically. The thyroid gland was also removed by surgery; it was normal completely. The mode of surgical treatment in patients with PTC arising from thyroglossal duct is still controversial. Some authors suggest a Sistrunk procedure in patients with no sign of disseminated disease while others prefer additional neck dissection and thyroidectomy.
Any cystic lesion in the neck should be assumed as malignant until proven otherwise. An FNA from the solid part of the cystic lesion would be of great value to establish the diagnosis preoperatively which certainly saves time and avoids unnecessary surgery.