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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 13-15

Ectopic cervical thymoma: A diagnostic dilemma


Department of Surgical Oncology, Sri Shankara Cancer Hospital and Research Centre, Bengaluru, Karnataka, India

Date of Submission20-Aug-2019
Date of Acceptance20-Oct-2019
Date of Web Publication27-Jun-2020

Correspondence Address:
Dr. M P Sreeram
Department of Surgical Oncology, Sri Shankara Cancer Hospital and Research Centre, Basavanagudy, Bengaluru - 560 004, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aiao.aiao_18_19

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  Abstract 


Thymic tumors are rare neoplasms that arise in the anterior mediastinum. The Incidence of ectopic cervical thymoma is very less. A 36-year-old female presented with a swelling in the front of the neck for the duration of around 1 year with a cytology report suggestive of lymphoma. She underwent positron emission tomography/computed tomography scan which showed only low-grade fluorodeoxyglucose uptake in the left neck node, no evidence of disease elsewhere. She underwent ultrasound-guided Tru-cut biopsy which was suggestive of round cell tumor favoring lymphoproliferative disorder which needed immunohistochemistry (IHC) for further confirmation. IHC was confirmative of thymoma, for which patient underwent surgery.. Final histology report was of Thymoma AB type, MASOKA Stage IIa. This case briefs about the diagnostic challenge in a case of neck swelling, for which none of the differential diagnosis was correlated. Surgery remains the mainstay of treatment for thymoma once the tissue diagnosis is confirmed.

Keywords: Cervical thymoma, neck swelling, thymoma


How to cite this article:
Kurpad V, Sreeram M P, Sasthry M. Ectopic cervical thymoma: A diagnostic dilemma. Ann Indian Acad Otorhinolaryngol Head Neck Surg 2020;4:13-5

How to cite this URL:
Kurpad V, Sreeram M P, Sasthry M. Ectopic cervical thymoma: A diagnostic dilemma. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2020 [cited 2020 Jul 9];4:13-5. Available from: http://www.aiaohns.in/text.asp?2020/4/1/13/288170




  Introduction Top


Thymus is a lymphoepithelial organ which creates a population of T-lymphocytes that helps for autoimmune regulation. During adulthood, thymus has a physiological involution, with only few remnants in the pericardial region. Ectopic migration of thymic tissue has been documented. Ectopic thymomas are documented with an incidence of approximately 4%.[1] This may be due to the remnants during the physiological descent from the pharynx to the mediastinum.

Cervical thymoma will present just like as any other neck mass. First-line differential diagnosis will include thyroid swelling, lymph nodal mass, and paraganglioma based on the anatomical location. Cytological evaluation may be not confirmative due to the presence of epithelial and lymphoid elements, it could be misdiagnosed as a squamous cell carcinoma or lymphoma.[2],[3] Our cytological diagnosis was suggestive of a lymphoma which required biopsy confirmation.


  Case Report Top


A 36-year-old female was admitted to our department with complaints of swelling in front of her neck for duration of 1 year. She had a 4 cm × 3 cm firm-to-hard swelling in the lower part of the neck. Swelling was just above the suprasternal notch extending laterally to the anterior border of sternocleidomastoid. Swelling did not move on deglutition and inferior extent could not be assessed. There were no engorged veins over the neck or chest wall. No bruit or pulsations felt. Mobility was restricted with no other palpable swellings.

Cytology done a year back showed reactive lymphadenitis. Magnetic resonance imaging neck was done recently showed a heterogeneously enhancing left lobe of thyroid lesion causing displacement of trachea toward the right, likely a neoplastic etiology. Repeat fine-needle aspiration cytology showed large cells with scant cytoplasm and oval-to-round nuclei displaying one to two prominent nucleoli, many small mature lymphocytes are seen in background. Hence, the possibility of lymphoma was considered. In view of suspected lymphoma, we performed positron emission tomography/computed tomography scan and ultrasound-guided Tru-cut biopsy. There was a low-grade metabolic activity on the left side neck nodes and anterosuperior mediastinum with no fluorodeoxyglucose-avid lesions anywhere else [Figure 1]. The biopsy was suggestive of a round cell tumor favoring a lymphoproliferative disorder. An initial diagnosis of peripheral T-cell lymphoma was made. As the history and clinicopathological findings did not correlate, hence the biopsy was reviewed, and extensive panel of immunohistochemistry markers was done. Markers such as CD3, Tdt, and CD5 were positive which confirmed the diagnosis of lymphocyte-rich thymoma. Serum AChR-Ab (acetylcholine receptor) was done and was within normal limits.
Figure 1: Positron emission tomography/computed tomography showing fluorodeoxyglucose uptake of the lesion

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This case was discussed in multidisciplinary tumor board and a decision to do thymectomy through low transcervical approach was taken [Figure 2]. The patient underwent the procedure, mass which was extending to the superior mediastinum 2–3 cm below the suprasternal notch and crossing the midline was resected and delivered in toto with an intact capsule and surrounding fat. Bilateral recurrent laryngeal nerves and parathyroids were identified and preserved. The patient withstood the procedure well, and postoperative recovery was uneventful. She was discharged on the 4th postoperative day.
Figure 2: Cervical tumor exposed

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Final histopathology report showed thymoma type AB (World Health Organization [WHO]) pT1 (5 cm × 4.5 cm × 2.8 cm), Stage IIA (modified Masokka staging). TVE was seen, and extension into the pericapsular connective tissue was noted. PNI was absent [Figure 3].
Figure 3: Type “AB” areas displaying sheets of bland spindle cells and areas displaying lymphocyte-rich population (H and E)

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  Discussion Top


Thymoma accounts for 20% to 30% mediastinal masses in adults.[4] Thymoma is unique in that it is quite often accompanied by paraneoplastic syndromes, notably myasthenia gravis (MG) in about one-third of cases, pure red cell aplasia, and hypogammaglobulinemia.[5],[6] Approximately 30% of patients with thymoma or thymic carcinoma have no symptoms when it is diagnosed. These are typically detected when doctors are looking for other diagnoses, during routine chest X-rays. Masokka in 1981 was the first one to classify thymic tumors, staging from I to IV;[7] Stage I (noninvasive) – microscopically and grossly encapsulated, Stage II thymoma invades beyond the capsule and into the nearby fatty tissue or to the pleura, Stage III tumors invade the neighboring organs (pericardium, lungs), and Stage IV has pleural or pericardial dissemination (IVA) or hematogenous/lymphatic dissemination (IVB). The WHO classification was based on the histological types – Type A, AB, B1, B2, and B3.[8] In 2004, the WHO proposed a new system of TNM classification and staging[9] [Table 1]. Overall survival of patients with thymic epithelial tumors according to stage, WHO classification, age, and histological subtypes are enlisted in [Table 2].
Table 1: World Health Organization staging system

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Table 2: Overall survival (stage and World Health Organization classification)

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Surgery remains the mainstay of treatment for thymomas. Complete resection of well-encapsulated, noninvasive thymoma is usually curative, with a risk of local recurrence of approximately 2%. Operative mortality can be expected and minimized with close attention to respiratory support when planning surgical treatment for patients with MG. The need for adjuvant treatment is based on three main factors: complete surgical resection, stage, and histology. Radiation therapy is not indicated following complete resection of a well-encapsulated thymoma. Radiation may be considered in rare cases of incompletely resected well-encapsulated thymoma. More recently, it has been proposed that radically resected thymoma Stage I and II WHO types A, AB, and B1 do not benefit from postoperative radiotherapy (RT) and therefore should not be treated.[10],[11] Adjuvant RT has been recommended in advanced-stage disease mainly when disease invades surrounding tissues (Stage III) or with R1-R2 residual disease after surgery. Adjuvant chemotherapy is not recommended for radically resected (R0) Stage I–II. Patients with high T-stage are candidates for neoadjuvant chemotherapy. Platinum-based combinations remain the standard of care (cisplatin, ifosfamide, and pemetrexed). The prospective clinical trial by the European Organization for Research and Treatment of Cancer, patients with advanced thymoma received PE regimen (cisplatin 60 mg/m2 on day 1 and etoposide 120 mg/m2 on days 1–3 every 3 weeks). Five complete responders and four partial responses were obtained for an objective response rate of 56%, with median response duration of 3.4 years. The median progression-free survival and OS were 2.2 and 4.3 years, respectively.[12] Use of targeted therapies such as epidermal growth factor receptor inhibitors, (TKI)Tyrosine Kinase Inhibitors inhibitors, insulin-like growth factor receptor inhibitors, angiogenesis inhibitors, somatostatin receptor inhibitors, histone acetylase inhibitors, TrKA/cyclin-dependent kinase inhibitors, and SRC inhibitors also been reported.[13]

Ectopic cervical thymoma is to be considered as one of the differential diagnoses for a palpable neck mass which do not fit in to the conventional differential diagnosis. Lack of awareness of this pathological condition may establish an erroneous diagnosis based on fine-needle aspiration cytology. Careful search for thymic epithelial cells in the aspirate will conclude a diagnosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Amodeo G, Cipriani O, Orsini R, Scopelliti D. Corrigendum to “A rare case of ectopic laterocervical thymoma”. Journal of Cranio-Maxillo-Facial Surgery 2013;41:7-9.  Back to cited text no. 1
    
2.
Chang ST, Chuang SS. Ectopic cervical thymoma: A mimic of T-lymphoblastic lymphoma. Pathol Res Pract 2003;199:633-5.  Back to cited text no. 2
    
3.
Mourra N, Duron F, Parc R, Flejou JF. Cervical ectopic thymoma: A diagnostic pitfall on frozen section. Histopathology 2005;46:583-5.  Back to cited text no. 3
    
4.
Levine GD, Rosai J. Thymic hyperplasia and neoplasia: A review of current concepts. Hum Pathol 1978;9:495-515.  Back to cited text no. 4
    
5.
Morgenthaler TI, Brown LR, Colby TV, Harper CM Jr. Coles DT. Thymoma. Mayo Clin Proc 1993;68:1110-23.  Back to cited text no. 5
    
6.
Choi H, Koh SH. Case reports. J Clin Neurosci 2008;15:1395-8.  Back to cited text no. 6
    
7.
Masaoka A, Monden Y, Nakahara K, Tanioka T. Follow-up study of thymomas with special reference to their clinical stages. Cancer 1981;48:2485-92.  Back to cited text no. 7
    
8.
Okumura M, Ohta M, Tateyama H, Nakagawa K, Matsumura A, Maeda H, et al. The World Health Organization histologic classification system reflects the oncologic behavior of thymoma: A clinical study of 273 patients. Cancer 2002;94:624-32.  Back to cited text no. 8
    
9.
Travis WD, Brambilla E, Muller-Hermelink HK. Harris CC for International Academy of Pathology (IAP). TNM Classification of Malignant Thymic Epithelial Tumours. Pathology and Genetics of Tumours of the Lung, Pleura, Thymus and Heart. Lyon: IARC Press; 2004. p. 147.  Back to cited text no. 9
    
10.
Ströbel P, Bauer A, Puppe B, Kraushaar T, Krein A, Toyka K, et al. Tumor recurrence and survival in patients treated for thymomas and thymic squamous cell carcinomas: A retrospective analysis. J Clin Oncol 2004;22:1501-9.  Back to cited text no. 10
    
11.
Wright CD. Pleuropneumonectomy for the treatment of masaoka stage IVA thymoma. Ann Thorac Surg 2006;82:1234-9.  Back to cited text no. 11
    
12.
Giaccone G, Ardizzoni A, Kirkpatrick A, Clerico M, Sahmoud T, van Zandwijk N, et al. Cisplatin and etoposide combination chemotherapy for locally advanced or metastatic thymoma. A phase II study of the European organization for research and treatment of cancer lung cancer cooperative group. J Clin Oncol 1996;14:814-20.  Back to cited text no. 12
    
13.
Scorsetti M, Leo F, Trama A, D'Angelillo R, Serpico D, Macerelli M, et al. Thymoma and thymic carcinomas. Crit Rev Oncol Hematol 2016;99:332-50.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2]



 

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