Published by : PROFESSIONAL MEDICAL PUBLICATIONS
|January - March 2007||
Schawanoma disguising as a Solitary Thyroid Nodule
Raja Najam-ul-Haq1, Ishtiaq Ahmed Chaudhary2
Schawannoma is a benign tumor arising from schawann’s cells. Schawannoma is arising from nerve tissue in central and peripheral nervous system is not uncommon, but is rarely found in body organs like pancreas, parotid gland or clinically simulate some other organ pathology. A case of Schawannoma clinically presenting as a solitary thyroid nodule is presented in this case report.
KEY WORDS: Schawannoma, Benign neoplasm, Thyroid nodule.
Pak J Med Sci January - March 2007 Vol. 23 No.1 128-129
1. Dr. Raja Najam-ul-Haq, FCPS
Department of Surgery
2. Dr Ishtiaq Ahmed Chaudhary, FCPS
Assistant Professor Surgery
1-2: Fauji Foundation Hospital,
Rawalpindi – Pakistan.
Dr. Raja Najam ul Haq
Senior Registrar Surgery,
House No. 9, Street. No. 6,
Hill View Lane, Adiala Road,
Rawalpindi – Pakistan.
* Received for Publication: December 12,
* Accepted: June 26, 2006
Nerve sheath tumors were first described in 1910 by Verocay.1 Schawanoma are benign, encapsulated, sub mucosal, neural sheath tumors derived from Schawann’s cells. Schawannoma’s are found anywhere in the body where schawann’s cell are found but they are more common in brain where they constitute about 8% of all intracranial tumors.2 We are presenting a rare case of benign Schawannoma mimicking as a left sided solitary thyroid nodule.
Case Report: A 19 years old girl presented with nine month history of discrete swelling over front of neck, left side. She also had complains of difficulty in swallowing and breathing. Swelling was gradually increasing in size. It was painful in the beginning which used to settle down with analgesics. Patient also gave history of increased appetite, heat intolerance, weight loss and palpitation off and on. Clinical examination revealed 7×5 cm sized, non tender swelling involving left thyroid lobe, moving with swallowing, firm in consistency. Cervical lymph nodes were not palpable. Her thyroid function tests were normal and fine needle aspiration cytology showed scanty follicular cells. Thyroid scan showed cold nodule in left thyroid lobe. With diagnosis of cold thyroid nodule, she was prepared for surgery. At operation thyroid was found to be normal and swelling was lying behind the left thyroid lobe adherent with caratoid sheath, giving an impression of solitary thyroid nodule (Fig-1). Excision of swelling was done carefully and wound closed. Histopath report revealed Schawannoma probably arising from branch of Vagus nerve.
Schawannoma’s are more common in females and usually occurs in midlife.2 They are generally solitary and can occur along any somatic or sympathetic nerve in the body except the olfactory and optic nerves, which lack schawann’s cell sheath and which are part of the central nervous system.3 They often arise from the 8th cranial nerve especially vestibular part of the acoustic nerve is involved most commonly(acoustic neuroma).4,5 They are slow growing, smooth surfaced and usually asymptomatic until symptoms are produced by pressure on adjacent structures.2 Symptoms they produce depend upon the site of involvement. Histologically, Schawannoma’s are encapsulated lesions that are characterized by cellular (Antoni A) and edematous (Antoni B) regions in varying proportions.2,5 Cellular areas that display palisading of nuclei and pooling of cytoplasm (Verocays bodies) are pathogonomic of Schawannoma. The Antoni B pattern is less cellular, lacks palisades and is more prone to degeneration and cyst formation. Immunohistochemistry of Schawannoma demonstrates S-100 positivity.6
Approximately 25% of Schawannoma arise in head and neck area.1 Some Schawannoma’s have been associated with Von Recklinghausen’s disease. In theses cases cutaneous and visceral nodules and café au lait spots were also observed.3 Surgery is the treatment of choice for Schawannoma’s of the head and neck because these tumors are usually benign, radio resistant and don’t reoccur on long term follow up.
Although Schawannoma is not an uncommon tumor but it is rare to find at some places in body where clinical presentation may disguise with some other pathology. Only a few cases of Schawannoma in the pancreas, parotid gland are reported in literature so for. The tumor may present as a cyst that grossly mimics the cystic lesion of these glands and leads to wrong diagnosis and mismanagement. Schawannoma disguising as a solitary thyroid nodule is a rare entity and no case was found on review of literature.
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2. Tareen S, Siddiq M, Mufti A, Ullah I. benign Schawannoma of the tongue: a case report. J Surg Pak (international) 2003;8(3): 43.
3. Cadoni G, Bucci G, Cornia L, et al. Schawannoma of the larynx presenting with difficult swallowing. Otolaryngol Head Neck Surg 2000;122:773-4.
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5. Sawamura Y, Shirato H, Sakamoto T, Aoyama H, Suzuki K, Onimaru R, et al. management of vestibular Schawannoma by fractionated stereotectic radiotherapy and associated cerebro-spinal fluid malabsorption. J Neurosurg 2003;99:685-92.
6. Gardner PM, Jentzen JM, Komorowski RA, Harb JM. Asphyxial death caused by a laryngeal Schawannoma: A case report. J Laryngol Otol 1997;1:117.
7. Paranjape C, Johnson SR, Khwaja K, Goldman H, Kruskal JB, Hanto DW. Clinical characteristics, treatment and outcome of pancreatic Schawannoma’s. J Gastrointest Surg 2004;8:706-12.
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