PÁGINA DEL RESIDENTE

 

What should the diagnosis be?

¿Cuál es su diagnóstico?

 

 

The case is presented of a 34 year-old male patient who attended the Department of Maxillofacial Surgery presenting with a right-sided lateral neck mass. It should be pointed out that he had a medical history that included an allergy to iodine contrast material. He had undergone surgery twice for frontonasal and malar fractures in 1998 and for left-sided pleomorphic adenoma in January 2002. In March 2004 he presented with a right-sided tumor-like mass on the side of his neck of recent onset and with a mid-jugular location. The mass had a maximum diameter of 3 cm diameter and it was situated medially to the sternocleidomastoid muscle. Its consistency was elastic, it was not attached to the deeper layers and it was slightly painful to palpation. A cervicofacial CAT scan was carried out that showed a large, right-sided, midjugular cystic lateral neck mass, which was not infiltrating neighboring structures, and bilateral cervical lymph node swelling (Fig.1). Given the impossibility of administering contrast material to the patient, MRI and FNA were used to determine the nature of the lesion and to increase the diagnostic possibilities (Fig.2). The echography- guided FNA was compatible with a nodular goiter and in the same procedure the rest of the neck was checked by echography. Two cystic lesions were found with a 4 mm diameter in the right thyroid lobe. The periphery of one was of solid tissue with multiple lateral cervical lymph nodes of 12 to 15 mm on the right side, and of 10 to 12 mm on the left side. MRI showed inflammation of the lymph nodes of the neck that was possibly metastatic and mainly right sided.

Following the results of the FNA we decided to carry out a gammagraphy and thyroid hormone measurement, but both tests proved negative. As there was no definitive diagnosis, an extirpationbiopsy was carried out of the right lateral neck mass. The macroscopic examination showed a tumor-like mass that had a maximum diameter of 4 x 3 cm that was brownish in color, spongy when cut and with an elastic consistency.(Fig.3)

Large cavities filled with protein- like erythrocytic material were observed microscopically. These were lined by a mono-series epithelium that was slightly hypertrophic, over a fibrous chorion with abundant leukocytes that formed secondary germinal centers. Focal hyperplasia of the epithelium lining had formed papillae in an ample connective axis (Fig. 4)

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Neck metastasis of occult papillary thyroid carcinoma

Metástasis cervical de carcinoma papilar tiroideo oculto

 

 

L. García Monleón¹, J. Calvo¹, C. Navarro Cuellar², S. González Otero¹, B. Duarte³, M. Cuesta Gil³

1 Médico residente. Hospital General Gregorio Marañón
2 Médico adjunto del Servicio de Cirugía Oral y Maxilofacial. Hospital de Guadalajara, Guadalajara
3 Médico adjunto del Servicio de Cirugía Oral y Maxilofacial. Hospital de Ciudad Real, Ciudad Real

Correspondence

 

 

The biopsy was compatible with lymphatic metastasis of papillary thyroid carcinoma. The appearance of a lateral neck mass at any age in life should always alert us. On most occasions a precise diagnosis is reached by means of bloodless diagnostic tests. However, a certain percentage of patients with these lesions will require a biopsy of a considerable size in order to reach the final diagnosis.

In this patient of ours, FNA aspiration proved to be a good indicator, as it was compatible with a nodular goiter. This finding, together with the rest of the tests carried out, made us consider four possible differential diagnoses.

a. Thyroglossal duct cyst

b. Branchial cyst with ectopic thyroid tissue

c. Inflamed cervical lymph nodes with thyroid inclusion

d. Possible neck metastasis of thyroid carcinoma

As the diagnostic biopsy was of lymphatic metastasis of papillary thyroid carcinoma, a total thyroidectomy was then carried out together with right-sided radical neck dissection and functional left-sided dissection. The anatomopathologic examination of the specimen showed a papillary thyroid carcinoma with a diameter of 4 mm in the right thyroid lobe with vascular invasion, together with lymph node invasion in the anterior compartment and upper right jugular invasion by a tumor with similar histological characteristics (Fig.5). The definitive diagnosis was of occult papillary carcinoma with lymph node metastases (T₁ N₂b M₀).

Radioiodine treatment was not possible given the patient’s history of allergy to iodine contrast material. He has been followed by the department of Endocrinology of the HGUGM and by our department. He is currently healthy and there has been no tumor recurrence.

 

Discussion

Cystic masses on the side of the neck in young adults (aged 16 to 40) are frequently associated with a benign process.¹ Malignant cysts on the side of the neck are very rare and they tend to originate principally from carcinomas of the oro-naso-pharyngeal region, and thyroid and salivary glands,^{2, 3} or from the rare and controversial primary branchiogenic carcinoma.^4-6 As was later confirmed in this case, there is a possibility of finding ourselves before the uncommon primary presentation of occult papillary thyroid carcinoma in the form of cystic metastasis in the neck.

Thyroid carcinomas usually manifest as thyroid-dependant asymptomatic masses that are evident on palpation. Primary clinical manifestations may appear in other forms that are less common: solitary metastatic lymphadenopathies, parapharyngeal masses,⁷ neck cysts,^{8- 14} hemoptysis¹⁵ and distant metastasis.^16-18 When a thyroid tumor is not detected with the usual diagnostic methods, and when lymph node inflammation is the primary manifestation, this is called occult carcinoma. This form of presentation of papillary carcinoma makes up 10 to 26% of cases.^1,16,19-24

These metastases normally appear as solid masses in the anterior compartment (central and paratracheal) and lateral (lower and mid-jugular region).^{20, 23-27} However, the primary presentation of papillary thyroid carcinoma with cervical metastasis of a cystic nature is extremely rare, with only 44 cases recorded in the scientific literature.^8-14 Rapid tumoral growth within metastatic lymph node inflammation provokes central liquefactive necrosis with the resulting cystic degeneration of the lymph node, thus explaining the findings in these cases.^{2, 11-13}

Imaging studies such as echographies and CAT scans are of great use for diagnosing cervical masses: the exact position is located and important morphological information is provided of the lesion and of the adjacent structures such as lymph nodes, salivary glands, thyroid... If the appearance of the mass is cystic, there should be information suggestive of a malignant etiology, such as a thick and irregular wall, an echogenic content in its interior, and the presence of septi.^{1,11,14,28,29} In other cases, this cyst can be indistinguishable from a branchial cyst, and this can lead to the suspected diagnosis being erroneous.

FNA has a large percentage of false negatives in malignant cell detection (from 50 to 67%) when used for lateral cystic masses of the neck with a non-affiliated etiology due to the low cellularity of the aspirate.^1,5,30-32 For this reason, if the puncture is negative for malignancy, an excisional biopsy should be carried out of the mass in order to reach the correct diagnosis, as in most cases it is erroneously labeled as a branchial cyst, and there will be delays in providing the correct diagnosis and treatment. While a positive puncture for malignancy is of undisputable value when planning surgery for a neck cyst, the high percentage of false negatives with regard to cystic lesions makes it of little use for ruling out the malignant pathology of this subgroup. With regard to the macroscopic appearance of the aspirate, most metastatic punctures of papillary thyroid carcinoma obtain a dark and viscous liquid. A low percentage can have anodyne characteristics and a serous yellowish aspirate can be observed,²⁸ and the metastatic etiology of the lesion is unsuspected.

Furthermore, in cases of microcarcinoma or occult papillary carcinoma, a palpable thyroid tumor is not observed, and even thyroid function tests and imaging tests such as echographies and CAT scans of the gland can appear normal, which makes reaching a correct preoperative diagnosis very difficult.^{8, 14}

Therefore, before a neck mass with cystic characteristics and an uncertain etiology, an excisional biopsy should be carried out, and the histopathologic analysis of the specimen will lead to the definitive diagnosis. Complete resection of the mass is recommended as, if malignant, carrying out an incisional biopsy will increase the risk of local recurrence in the area of the biopsy.¹⁰

If, as in our case, the anatomopathologic analysis shows thyroid tissue with signs of malignancy, on most occasions this will correspond to cervical metastasis of thyroid carcinoma. There are cases in the scientific literature of malignant degeneration of an ectopic thyroid tissue within a branchial cyst,^2,3,6 but if the primary manifestation of thyroid carcinoma as cystic metastasis in the neck is very rare, finding a branchial cyst that has become malignant is even more so.

With regard to the prognosis of these patients, different systems of staging and factors predicting aggressive behavior have been used that are similar to those used for differentiated carcinoma of the thyroid.^{33, 34} With regard to the factors that can predict the aggressiveness of papillary microcarcinomas, Hay & cols. found independent risk factors that consisted in the extent of the thyroid resection and the presence of pathologic lymph nodes on diagnosis.³⁵ Sugitani and Yanagisawa found that that the presence of nodal metastasis in the neck of at least 3 cm and extracapsular extension of the tumor on diagnosis was linked with high-risk factors and aggressive behavior.³⁶ Coinciding with these authors, Yamashita & cols.,³⁷ in a revision of 1.628 papillary microcarcinomas, found that extracapsular invasion of lymph node metastasis was an indicator of a higher recurrence rate. However, despite the fact that the presence of cervical metastasis in a papillary carcinoma on diagnosis leads to a larger percentage of local relapses, different studies have not been able to show that there is any difference with regard to survival.^25,33,36-38

With regard to outcome of the so-called papillary microcarcinomas (according to the latest WHO classification, those with a diameter of less than 10 mm³⁹), the greatest incidence found in autopsy studies seems to suggest that most of these follow a benign course.⁴⁰ In a recent study Ito & cols.⁴¹ observed the progress of a group of 162 patients diagnosed with papillary thyroid microcarcinoma by FNA. They found that the size of the lesion had diminished or it had remained stable over 5 years in 72% of these patients. However, this study does not clarify: the percentage of lymphatic metastases produced during the follow-up period, the total number of patients with progression of the disease, as 56 of these patients underwent second stage surgery, nor is the high patient loss explained (70% over five years). On the other hand there are studies that have shown a locoregional recurrence rate between 2 and 18%, depending on the extension of the primary tumor (pathologic lymph nodes on diagnosis, extracapsular extension, etc.) and on the type of surgery.^25,35,42,43 Even in a small percentage of patients the presence of distant metastasis was observed.^18,35,42

In view of this and despite that papillary thyroid carcinoma has generally a very good prognosis, the best therapy continues being the subject of much debate. Patients should be stratified according to the risk of malignant behavior (using scoring such as AMES, AGES o MACIS)^34,44,45 and the therapy shown to increase survival in this group should be applied. With regard to how extensive the thyroid dissection should be, for low-risk patients carrying out a subtotal or total thyroidectomy has not been shown to increase survival with regard to the resectioning of the affected thyroid lobe.⁴⁴ However some authors carryout, and they recommend carrying out, a routine total thyroidectomy based on the high frequency of multicentrality and bilateral involvement of the gland,²⁶ the need for posterior ablative treatment with radioiodine, the possibility of using thyroglobulin as a recurrence marker if all thyroid tissue has been eliminated, and the potential transformation to anaplastic carcinoma. ^17,44,46,47 In high-risk patients, carrying out a bilateral thyroidectomy is recommended as it has been shown to increase survival significantly.⁴⁴ In this case of ours, a total thyroidectomy was carried out as it was considered a highrisk case, given the presentation mode.

With regard to the indication for lymphadenectomy, we should differentiate between high and low-risk patients. In the latter, survival does not change after a prophylactic lymphadenectomy is carried out.⁴⁴

The extent of lymphadenectomy is a controversial subject. Some authors recommend carrying out a modified radical neck dissection as in their series this technique has resulted in an increase in the survival of high-risk patients (patients with metastatic lymph node swelling, those with a primary tumor that invades beyond the capsule and in patients that are over 60).⁴⁸

With regard to the need for bilateral modified radical neck dissection, some studies advise carrying this out in those cases that present a high risk of contralateral lymph node metastasis such as: those with a primary tumor of a large size or near the thyroid isthmus, with extracapsular extension, invasion of neighboring tissue or the presence of lymphadenopathies of a large size.⁴⁹

With regard to papillary thyroid carcinoma, given the development of imaging techniques for diagnosis and the use of fine needle aspiration, there has been an increase in incidental diagnoses in recent years. As a result, there has been controversy surrounding the need for therapy in these cases and how extensive this should be.³⁵

With regard to the extent of a thyroidectomy, Hay and cols.,³⁵ in a study of 535 papillary microcarcinomas, observed a greater percentage of locoregional recurrences in those patients subjected to a unilateral lobectomy compared with those that underwent a bilateral resection of the thyroid (20% and 5% of recurrence at 20 years respectively), but no statistically significant differences were observed with regard to subtotal, near-total or total thyroidectomies. These authors individualized two factors contributing to the risk of locoregional recurrence: the extent of surgery and the lymphatic metastasis at initial presentation. Given the high percentage of multifocality and bilaterality that was observed (20% and 10% respectively) and that recurrences tend to appear in the remaining thyroid tissue, these authors were in favor of a near total thyroidectomy. On the other hand Baudin and cols.⁴² found two factors that influenced the risk of locoregional recurrence: tumor multifocality and the extent of the surgery, with the percentage of recurrences being 1.2 and 8.6% in unifocal and multifocal tumors respectively, and of 2.3% following a total thyroidectomy as opposed to 8.2% with lobectomy. As a result of this, they concluded that treatment should be individualized according to the extension of the disease. They recommend a loboisthmusectomy for tumors with just one focus, and carrying out a subtotal or total thyroidectomy in cases of multiple foci. In spite of this, distinguishing preoperatively those patients with negative prognostic factors is impossible given that current imaging techniques are not sensitive enough for detecting invasion of the thyroid capsule, multifocality and microscopic lymphatic metastasis. As a result of this, there is still much debate as to the most suitable therapy. Offering the patient a bilateral thyroidectomy would therefore appear reasonable as it should not involve any complications if carried out by expert hands, and there are fewer recurrences when compared with more conservative surgery.

If papillary microcarcinoma includes clinically or radiologically significant lymphadenopathies at diagnosis, carrying out modified radical cervical resection is recommended, as it has been demonstrated that the number of cervical recurrences is reduced.^{25, 50} Wada & cols.²⁵ even observed a rate of lymph node recurrence of 16.7%, which represents a similar percentage to that found in larger sized papillary carcinomas.^{33, 50} These findings suggests that patients with palpable lymphadenopathy have a high risk of nodal recurrence regardless of the size of the primary carcinoma. Cervical dissection should therefore be guided by the same criteria. In cases of papillary thyroid microcarcinomas with no palpable inflammation, the same study by Wada did not find a decrease in the number of recurrences in the group treated with prophylactic cervical lymphadenectomies. They therefore concluded that while therapeutic cervical dissection is indicated, prophylactic dissection is not beneficial in those without palpable lymphadenopathy.

 

Conclusions

The aim of this case was to stress that even though most lateral neck cysts in young adults correspond to a benign pathology, the clinician should consider the possibility that this is in fact cervical metastasis of occult carcinoma and that, as a result, papillary thyroid microcarcinoma should be included in the possible differential diagnoses. Therefore, if a young adult presents with a lateral neck mass with cystic characteristics, the diagnostic protocol should be the following:

1. Identification of the possible risk factors for malignancy (family medical history for thyroid carcinoma, radiotherapy during infancy, etc.).

2. Exhaustive physical examination that includes the upper aerodigestive tract and the thyroid gland. 3. FNA of the cervical cyst (bearing in mind the high percentage of false negatives for malignant cells that are observed in other lesions).

4. Echography and/or CAT scan and/or cervical RMI (with evaluation of the mass, possible cervical lymph node swelling and thyroid gland).

5. If there is anything suggestive of thyroid disease, a thyroid function test should be carried out that includes thyroid hormone determination and a gammagraphy of the gland.

6. As a lateral cystic neck mass in a young adult tends to be of a benign etiology (in more than 90% of cases), the confirmation diagnosis tends to be obtained after the surgery and after the histopathologic analysis of the resected specimen. Only if malignancy is suspected in the echography or CAT scan is carrying out an intraoperative biopsy indicated in order to amplify the surgery if necessary.

 

 

Correspondence:
Laura García Moleón
C/ Antonio Zapata, 14 2ºB
28002 Madrid, España
Email: lauramoleon@hotmail.com

 

 

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