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LETTER TO EDITOR  
Year : 2018  |  Volume : 61  |  Issue : 4  |  Page : 630-632
Lipofibroadenoma with B1 thymoma: A case report of a rare thymic tumor


Department of Pathology, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India

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Date of Web Publication10-Oct-2018
 

How to cite this article:
Hui M, Paul TR, Uppin SG, Jyothi N. Lipofibroadenoma with B1 thymoma: A case report of a rare thymic tumor. Indian J Pathol Microbiol 2018;61:630-2

How to cite this URL:
Hui M, Paul TR, Uppin SG, Jyothi N. Lipofibroadenoma with B1 thymoma: A case report of a rare thymic tumor. Indian J Pathol Microbiol [serial online] 2018 [cited 2018 Dec 15];61:630-2. Available from: http://www.ijpmonline.org/text.asp?2018/61/4/630/242980




Editor,

Lipofibroadenoma is an unusual thymic tumor resembling fibroadenoma of the breast. It is categorized under “rare thymomas” in the World Health Organization classification.[1] It accounts for 6%–17% of all thymomas occurring predominantly in the age group of 40–50 years.[2] The clinicopathological features are still unclear. Very few cases have been reported till date.

A 29-year-old male presented with cough and expectoration for the past 6 months. There was no shortness of breath or hemoptysis. The symptoms had a gradual onset and had progressed over time. There was no history of asthma or tuberculosis. On examination, pulse rate was 74/min and blood pressure was 119/70 mmHg. There was no pallor, icterus, clubbing, edema, or cyanosis. On systemic examination, there were reduced breath sounds in bilateral lungs. Routine hematological and biochemical investigations were within normal limits. Hematological parameters revealed hemoglobin – 12.7 g%, packed cell volume – 38.9%, total white blood cell count – 12,900/mm3, and platelet count – 2.9 lakhs/mm3. Electrocardiogram and chest X-ray were within normal limits. Contrast-enhanced computed tomography (CT) chest showed a well-circumscribed homogeneous minimally enhancing anterior mediastinal mass with soft-tissue attenuation. A diagnosis of benign thymic neoplasm – thymoma was favored over complicated thymic cyst. Magnetic resonance imaging revealed a well-marginated lesion measuring 54 mm × 24 mm × 65 mm separated from the mediastinal vessels with preserved fat planes, suggestive of benign thymic neoplasm [Figure 1]b. Positron emission tomography CT scan showed an anterior mediastinal mass with no fluorodeoxyglucose uptake, suggestive of pericardial cyst/thymoma. Thoracoscopic excision of the mass was done and sent for histopathological examination. Intraoperatively, there was a well-encapsulated mass in the anterior mediastinum which was separated from the pericardium and great vessels posteriorly. The mass was also abutting the right phrenic nerve posteriorly. Grossly, it was a lobulated mass covered with adipose tissue. On cut section, the mass was firm homogeneous and gray-white.[Figure 1]a. Microscopic examination revealed a lesion comprising strands of compressed bland epithelial cells separated by fibrotic and hyalinized stroma. The morphology resembled fibroadenoma of the breast [Figure 1]c and [Figure 1]d. Lobules of adipose tissue, calcification, and lymphoid cells with Hassall's corpuscles were entrapped in the stroma [Figure 1]e. The adjacent areas showed type B1 thymoma [Figure 1]f, [Figure 1]g, [Figure 1]h. Immunohistochemistry was done with cytokeratin (CK) 19, CD3, CD20, and Tdt. CK19 was positive in the compressed epithelial component as well as dispersed epithelial cells of thymoma. The lymphoid cells of the thymoma component are positive for both CD3 and Tdt, whereas the lymphoid cells around the compressed epithelial component were positive for CD3 and CD20 but negative for Tdt [Figure 2]. In view of both epithelial and fibrous component admixed with adipose tissue, the tumor was diagnosed as lipofibroadenoma with type B1 thymoma. The postoperative recovery was uneventful, and the patient was discharged in stable condition.
Figure 1: (a) Cut section of the excised mass is homogeneous with myxoid change. (b) Lobulated intermediate-to-high-signal intensity lesion noted in the anterior mediastinum abutting superior vena cava and arch of aorta. (c and d) The tumor shows irregularly connected strands of compressed bland epithelial cells with entrapped lymphoid cells (H and E, c ×100, d ×400). (e) Intervening areas show lobules of adipose tissue (H and E, ×100). (f-h) Adjacent areas show Type B1 thymoma (H and E, f and g ×100, h ×400)

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Figure 2: Cytokeratin 19 highlights the compressed (a) epithelial cells and (b) epithelial component of thymoma. (c and d) Immunostaining with Tdt is negative in the lymphoid cells of lipofibroadenoma component and positive in immature T-cells of thymoma. (e and f) CD3 is positive in the entrapped lymphoid cells and thymoma component

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Lipofibroadenoma is an uncommon tumor of the thymus presenting with cough and dyspnea. It is commonly associated with myasthenia gravis. However, its association with hypogammaglobulinemia and pure red cell aplasia is rare.[2] Kuo and Shih. reported a case of lipofibroadenoma in a 62-year-old male who presented with dyspnea and dizziness, and the tumor was accompanied by pure red cell aplasia and Type B1 thymoma.[3] Qu et al. reported another case in a 21-year-old male who was asymptomatic and was not associated with pure red cell aplasia or thymoma.[4] In all the cases including the present one, the tumor was located in the anterior mediastinum, which has been attributed as the most common location in literature. The other sites of involvement are neck, pleura, and lung.[2] Similar to Kuo and Shih, the present case was also accompanied by Type B1 thymoma.[3] Its association with thymomas has led to the hypothesis that thymic epithelial cell precursor may be responsible for the development of these tumors.[1] The hematological parameters were within normal limits, and there was no evidence of pure red cell aplasia in the present case. Histopathology is gold standard for diagnosis.[4] The differential diagnosis includes thymolipoma and sclerosing thymoma. Like lipofibroadenomas, thymolipomas are also known to be associated with myasthenia gravis.[5] However, histologically thymolipomas are characterized by predominance of adipose tissue and lack fibrous tissue component. The sclerosing thymomas are differentiated from lipofibroadenomas by the presence of large islands of polygonal cells in a dense collagenous stroma without intermixed adipose tissue.

Thymectomy is the treatment of choice. It rarely invades the pleura, pericardium, great vessels, or adjacent organs and has a recurrence rate of <10%.[6],[7] The striking morphology and immunohistochemical features of this entity have been highlighted in this article in view of its rarity and classic histomorphology.

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.
Chen G, Chalabreysse L. Other rare thymomas. In: Travis WD, Brambilla E, Burke AP, Marx A, Nicholson AG, editors. WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart. 4th ed. Lyon: IARC; 2015. p. 210-1.  Back to cited text no. 1
    
2.
Aydin Y, Sipal S, Celik M, Araz O, Ulas AB, Alper F, et al. A rare thymoma type presenting as a giant intrathoracic tumor: Lipofibroadenoma. Eurasian J Med 2012;44:176-8.  Back to cited text no. 2
    
3.
Kuo T, Shih LY. Histologic types of thymoma associated with pure red cell aplasia: A study of five cases including a composite tumor of organoid thymoma associated with an unusual lipofibroadenoma. Int J Surg Pathol 2001;9:29-35.  Back to cited text no. 3
    
4.
Qu G, Yu G, Zhang Q, Ma J, Wang X. Lipofibroadenoma of the thymus: A case report. Diagn Pathol 2013;8:117.  Back to cited text no. 4
    
5.
Ríos Zambudio A, Torres Lanzas J, Roca Calvo MJ, Martínez Barba E, Parrilla Paricio P. Thymolipomas in association with myasthenia gravis. J Thorac Cardiovasc Surg 2001;122:825-6.  Back to cited text no. 5
    
6.
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. 6
    
7.
Chalabreysse L, Roy P, Cordier JF, Loire R, Gamondes JP, Thivolet-Bejui F, et al. Correlation of the WHO schema for the classification of thymic epithelial neoplasms with prognosis: A retrospective study of 90 tumors. Am J Surg Pathol 2002;26:1605-11.  Back to cited text no. 7
    

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Correspondence Address:
Tara Roshni Paul
Department of Pathology, Nizam's Institute of Medical Sciences, Panjagutta, Hyderabad - 500 082, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/IJPM.IJPM_443_17

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