Occult papillary thyroid carcinoma presenting as a parapharyngeal metastasis

Case Reports Occult Papillary a Parapharyngeal

Thyroid Carcinoma Metastasis

Levent Saydam, MD, Tayyar Kalcioglu, and Mehmet Gurer, MD

(Editorial Comment: The authors’ observations suggest that Rouviere’s original anatomic study showing lymphatic channels between the thyroid and the retropharyngeal space are probably correct.)

The neoplastic involvement of the parapharyngeal space is a rare condition that represents only 0.5% of all head and neck tumors.1-3 The benign salivary gland tumors and tumors of neural tissue origin constitute the great majority of these cases. 3-6To encounter a metastatic thyroid cancer in the parapharyngeal space is an extremely unusual occurrence. The literature review showed only six cases published previously.7-*2 In this article, we report a patient presenting with a left parapharyngeal mass. The pathological examination showed a metastatic thyroid papillary cancer. Besides the unusual localization of the lesion, this case also confirms the anatomic study of Rouviere13 showing the existence of lymphatic channels between the thyroid lymphatics and the parapharyngeal space.

CASE REPORT A %-year-old woman was admitted to our department with a sensation of fullness in the throat for 1 year. A left submucosal mass of the lateral pharyngeal wall and marked medial displacement of the left tonsillary area were noted on physical examinaFrom the Departments of Otolaryngology and Surgery, lnonu University School of Medicine, Malatya; and the Department of Surgery, Ankara University School of Medicine, Ankara, Turkev. Address reprint requests to Levent Saydam, MD, Department of Otolaryngology, lnonu University School of Medicine, Malatya 44300, Turkey. Copyright o 1999 by W.B. Saunders Company 0196-0709/99/2003-0006$10.00/0 166

Presenting

MD, Ahmet Demirkiran,

as

MD,

tion. The rest of the examination was unremarkable. The computed tomographic scan showed a left parapharyngeal mass with moderate contrast enhancement (Fig 1). Almost the entire parapharyngeal space was occupied by the mass. Surgical excision of the mass was planned with these findings. After the initial isolation of the major neck vessels, the pharyngolaryngeal complex was bluntly dissected off the prevertebral fascia and slightly retracted toward the contralateral side to improve the surgical exposure. The mass was found to be heterogeneous in consistency with cystic and solid areas. Frozen-section examination confirmed papillary cancer metastatic to the lymph node. The operation was then extended to include a total thyroidectomy and bilateral modified neck dissections. The pathological examination confirmed the initial frozen-section diagnosis and also showed a small focus of papillary carcinoma within the upper portion of the left thyroid gland (Figs 2 and 3). The patient declined any further treatment. She remains without evidence of the disease 3 years later.

DISCUSSION Brief Surgical Anatomy of the Parapharyngeal Space Parapharyngeal space is usually depicted as a funnel- or reversed-pyramid-shaped neck compartment lying between the base of skull superiorly and hyoid bone inferiorly. The lateral border is defined by the ascending ramus of the mandible and the parotid gland. The prevertebral fascia limits the space posteriorly. The pterygomandibular raphe and superior constrictor muscle both delineate the anterior border. The medial wall consists of the fascia of the constrictor muscles and the tensor and levator veli palatini muscles. The styloid process divides the parapharyngeal space into an anterior (prestyloid) and

American Journal of Otolaryngology, Vol20, No 3 (May-June), 1999: pp 166-166

THYROID

CANCER

METASTATIC

TO THE

PHARYNGEAL

SPACE

167

Fig 3. Papillary carcinoma in the thyroid gland in the same patient (H&E, original magnification x 100.)

Fig 1. The mass filling almost the entire left parapharyngeal space.

posterior (poststyloid) compartment. The prestyloid compartment that lies anterior to the fascia of the tensor veli palatini contains the deep lobe of the parotid gland, branches of the maxillary artery, lingual and auriculotemporal nerves, and loose connective tissue. The poststyloid or visceral compartment is occupied by the contents of the carotid sheath, the last four cranial nerves, cervical sympathetic chain, and lymphatic tissue.

Lymphatics

of the Thyroid

Gland

As shown by several anatomic studies,14J5 lymphatics of the thyroid gland accompany the veins toward three directions. Inferiorly, these vessels communicate with the upper

Fig 2. Metastatic thyroid papillary carcinoma within the lymph node. (H&E, original magnification x20.)

mediastinal lymph nodes through the pretracheal and paratracheal lymph nodes and lymph channels that follow the recurrent laryngeal nerves. The superomedial lymphatic group connects to the prelaryngeal (Delphian node) and the upper deep jugular lymph nodes. Lateral thyroid lymphatics drain into the middle and lower jugular system. In his classical study on the lymphatic system, Rouviere13 described a lymphatic bundle connecting the posterior and superior compartments of the lateral thyroid lymph vessels to the retropharyngeal lymphatic system. He reported that this anatomic variation was present in one fifth of the cases. Despite the abundant anatomic connections, the parapharyngeal space is a very unusual location in which to encounter a metastatic deposit originating from a primary thyroid tumor. To the best of our knowledge, there are only six reported cases7-l2 of a solitary thyroid metastasis in the parapharyngeal space as an initial manifestation. These were two follicular carcinomas,8J0 one medullary carcinoma,g and three papillary carcinomas.7J1J2 In the papillary cancer cases, the investigators give credit to Rouviere’s13 critical anatomic description to explain the possible route of dissemination of the disease in their cases. As also stated in these reports, the connection just posterior to the fascia of the superior constrictor muscle, allowing the parapharyngeal and the retropharyngeal spaces to freely communicate with each other, deserves special attention. Once they reach the retropharyngeal lymphatics, tumor cells can easily involve the parapharyngeal space through this anatomic dehiscense. This is an important

168

anatomic fact because these lymphatic channels, originally described by Rouviere,13 may be the only explanation of the transportation of tumor cells to the parapharyngeal space through the retropharyngeal compartment. It can be postulated that laryngeal or hypopharyngeal carcinomas invading the pharyngeal walls also metastasize to the parapharyngeal space by the same anatomic pathways as reported previously by some investigators.16J7 Ballantyne’” reported a 44% chance of tumor dissemination to the retropharyngeal lymph nodes in patients with epidermoid cancer of the pharyngeal walls. Because of the previously mentioned anatomic features, meticulous evaluation and, if necessary, extension of the neck dissection to include this region should be considered in these cases.

CONCLUSION This case report emphasizes two points. First, despite its rarity, to encounter metastatic deposits in the parapharyngeal space is a diagnostic possibility, and a frozen-section examination of the specimen should be an integral part of the surgical procedure in this location. Second, especially in papillary thyroid cancer cases, routine computed tomographic or magnetic resonance examination of the midline neck, jugular chain, and upper mediastinal areas to show the possible neck metastases should be extended to include both parapharyngeal areas. Our case and others’ support Rouviere’s anatomic study that gives clear evidence of the connections between the jugular chain and retropharyngeal lymph nodes.

SAYDAM

ET AL

REFERENCES 1. Lawson VG, LeLiever WC, Makerewich LA, et al: Unusual parapharyngeal lesions. J Otolaryngol8:241-249, 1979 2. Batsakis JG, Sneige N: Pathology consultation: Parapharyngeal and retropharyngeal_ space diseases. Ann Otol RhinolLaryngol98:320-321, 19893. Work WP. Hvbels RL: A studv of tumors of the parapharyngeal space. Laryngoscope>84:1748-1755,1974 4. Som PM, Biller HF, Lawson W: Tumors of the parapharyngeal space: Preoperative evaluation, diagnosis and surgical approaches. Ann Otol Rhino1 Laryngol 90:315,198l 5. Maran AGD, Mackenzie IJ, Murray JAM: The parapharyngeal space. J Laryngol Otol98:371-380, 1984 6. Hughes KV, Olsen KD, McCaffrey TV: Parapharyngeal space neoplasms. Head Neck 17:124-130,1995 7. Robbins KT, Woodson GE: Thyroid carcinoma presenting as a parapharyngeal mass. Head Neck Surg 7:434436,1985 8. Lau WF, Lam KH, Wei W: Parapharyngeal space tumors. Aust N 2 J Surg 56:835-842, 1986 9. Pearlman SJ, Lawson W, Biller HF: Occult medullary carcinoma of the thyroid presenting as neck and parapharyngeal metastases. Otolaryngol Head Neck Surg 99:509512,1988 10. Carrau RL, Myers EN, Johnson JT: Management of tumors arising in the parapharyngeal space. Laryngoscope 100:583-589,199O 11. Ferrario F, Roselli R, Macchi A: Occult thyroid carcinoma presenting as a parapharyngeal _ _ mass. J Laryngo1 Otol109:1204-12106, 1995 12. Sirotnak R: Pauillarv carci,,11. Loree TR. Penetrante noma of the thyroid me&static to the p&apharyngeal space. Ear Nose Throat J 76:342-344,1997 13. Rouviere H: Anatomy of the Human Lymphatic System: A Compendium Translated From the Original ‘Anatomie des Lymphatiques de I’Homme’ and Rearranged for the Use of Students and Practitioners by M.J. Tobyas. Ann Arbor, MI, Edward Bros, 1938 14. Chouke KS. Whitehead RW. Parker AE: Is there a closed lymphatic’ system connecting the thyroid and thymus glands? Surg Gynecol Obstet 54:865-871, 1932 15. Hollinshead WH: Anatomy for Surgeons; The Head and Neck, vol 9 (ed 2). Hagerstown, MD, Harper & Row, 1968, pp 576-577 16. Ballantyne AJ: Principles of surgical management of cancer of the pharyngeal walls. Cancer 20:663-667, 1967 17. Hasegawa Y, Matsuura H: Retropharyngeal node dissection in cancer of the oropharynx and hypopharynx. Head Neck 16:173-180,1994