Ultrasound neck showed a large cystic mass on the left side of neck suggestive of necrotic lymph nodes. Thyroid gland appeared normal in size and shape. Small multiple hypo echoic nodules were visible in right lobe, one measuring 0.3x0.2 cm. The small size of the nodules was also difficult to get the exact location while doing fine needle aspiration cytology (FNAC) for confirmation of presence or absence of malignancy. Therefore, these nodules were not further investigated with FNAC of thyroid.

Thyroid scan showed normal thyroid status, with no cold nodules in neck identified and the swelling over left side of neck was extra thyroidal. FNAC of the swelling was suggestive of cyst. Patient was advised computed tomography (CT) scan of neck with contrast.

CT scan of neck with contrast revealed a multi-loculated cystic mass lesion in the posterior triangle of the left side of neck with thin enhancing septa. Thyroid gland did not show any nodule on CT scan neck. Bilateral cervical lymphadenopathy less than 1 cm at level I and II was also seen. Findings were more in favour of a benign neoplastic lesion such as lymphangioma. Excisional biopsy of mass was advised (Figures 1 and 2). Per-operatively, the lesion was a vascular looking mass just beneath the sternocleidomastoid muscle. There was no soft tissue connection with the left thyroid lobe. The mass was excised completely, and the wound was closed over negative pressure drain. Patient’s post-operative recovery was uneventful.

Histopathology report of the mass showed cystic lymph node exhibiting a metastatic lesion with a papillary  architecture. The tumor cells show positive staining for Thyroid transcription factor 1. The histopathology concluded that the neck lump was Metastatic Papillary Carcinoma of Thyroid Gland.

As this was an unusual case, a multi-disciplinary meeting was called to discuss the best possible option for the patient’s management. The recommendation was for ‘Total Thyroidectomy’ followed by radioactive iodine-ablation as the next step of management. However, the patient refused for any further surgery.

To further evaluate the status of thyroid, an ultrasound neck was repeated for post-operative evaluation which showed multiple iso-echoic nodules in the right lobe of thyroid gland, one measuring 0.3 cm in diameter. Left lobe of thyroid gland was normal with no solid or cystic nodules seen. Small sub-centimeter lymph nodes were noted in the upper part of right side of the neck.

Considering that the left thyroid lobe was absolutely normal on the side of the lesion, the thyroid scan was normal with no cold nodules and the patient was asymptomatic, he was advised for monthly follow up. Evaluation was repeated one year post-operatively and follow up ultrasound done at this visit revealed a normal thyroid gland with no evidence of cervical lymphadenopathy. After three years post-operative follow-up, clinically there was no swelling in the neck or thyroid gland.

DISCUSSION

Cystic lesions such as Branchial cleft cysts, Dermoid cysts, Hemangioma and Cystic Hygroma can all present as lateral neck swellings. However, the clinical evaluation of adults through middle to older age group presenting with lateral neck lumps is aimed more specifically at the exclusion of malignancy especially when the patient presents with a slow growing painless neck mass. Therefore, thorough evaluation is a must to reach an accurate diagnosis.

In our patient, taking his age and the nature of the lump under consideration we had to come to a diagnosis of exclusion, suspecting a malignancy. In a similar case reported by P Krishnappa, a cystic lesion in the patient’s neck laterally proved to be an occult papillary carcinoma [1].

The most specific sonographic finding of papillary carcinoma is the presence of punctuate, non-shadowing echogenic foci termed micro-calcifications, associated with psammoma bodies for suspecting papillary thyroid carcinoma. This is the finding having high specificity (85-95%) and low sensitivity (25-59%) [2]. Although FNAC is reported as being highly accurate by Lowhagen and his colleagues [3], there can be a high rate of unsatisfactory aspirates, particularly in cystic or partly cystic swellings. This was true in our case  in  which  only  the  confirmation  of  the  cystic  nature  of  the  swelling  was  obtained. The size of nodules in thyroid gland which are considered significant for suspicion of malignancy is 0.5 cm; the reported ones in our case were less than that, therefore did not appear significant preoperatively. As the nodules within the thyroid gland were small (0.3 cm) and were on the contralateral side of the cystic neck lesion, the FNAC of thyroid nodule itself was not attempted. CT scan neck revealed a multi-loculated cystic mass lesion with enhancing  septa favoring a benign neoplastic lesion. The thyroid gland was reported normal on CT scan.

If the results of the ultrasound scan and FNAC are inconclusive, excisional biopsy of the cyst is essential so as to rule out malignancy and to avoid the delay in the diagnosis and management [4]. The histopathology revealed Metastatic Papillary Carcinoma of Thyroid Gland.

Solitary lateral cervical cystic mass is an uncommon presentation of papillary thyroid carcinoma (PTC) [4]. In up to 20% of all patients, lymph node metastases may even be the sole or initial manifestation of disease (occult primary tumor) [5]. According to the patients reviewed by Monchik JM, sometimes the primary thyroid tumor is less than 1 cm and at other times only microscopic, the extensive nodal metastasis has led them to favor near total or total thyroidectomy and modified neck dissection in this entity [6].

Rarely, PTC presents as a lateral cystic neck mass without palpable lesion in the thyroid gland. The origin of these cysts is controversial. Some authors think that it represents a malignant transformation of ectopic thyroid tissue. Others think that it represents a secondary metastatic spread from occult thyroid lesion to the lymph node which underwent central liquefaction with cystic formation [7].

In the case series by Al-Ashaa [4], five patients with papillary thyroid carcinoma presenting as a lateral neck cyst were studied, three patients had total thyroidectomy and modified radical neck dissection out of which two patients were followed up for 5 years and were completely free of the disease.

 One out of every 10 lateral cervical cysts in young adult patients represents lymphatic metastases from occult thyroid  carcinoma. The appearance of a solitary lateral cervical cystic mass as the only initial presenting symptom of occult thyroid carcinoma is extremely rare, with  approximately 40 cases previously reported in the literature. Seven et al. [8] have reported 11% of thyroid  malignancy in patients with primary diagnosis of lateral cervical cyst. Our patient had refused ‘Total thyroidectomy with neck dissection so he was advised to keep a regular follow up.

On follow up, ultrasound neck after 1 year revealed no cervical lymphadenopathy and a completely normal thyroid gland. On three years’ post-operative follow up, clinically there is no thyroid or lateral neck swelling. According to published studies of previous case reports, most  were dealt with complete removal of the thyroid gland followed by appropriate radiotherapy and good prognosis. In our case, the patient is free of disease three years post-operatively though the patient had refused treatment advised. However, the origin of the metastatic lesion remains unknown.

CONCLUSION 

Solitary lateral cystic swelling of the neck is an uncommon presentation of papillary thyroid carcinoma, when occurs is usually considered as a benign lesion. Metastatic presentation of PTC as a lateral neck swelling is indeed a diagnostic challenge. This case report accentuates that patients presenting with a solitary lateral neck swelling must be treated with high index of suspicion. Excisional biopsy is indicated in all such presentations to rule out malignancy if FNAC comes out to be inconclusive.