|LETTER TO THE EDITOR
|Year : 2017 | Volume
| Issue : 2 | Page : 140-141
Primary thyroid lymphoma – An uncommon entity
Rashmi Patnayak1, Rohini Choudhuri1, Debashis Samal2, Debahuti Mahapatra1, Kumudini Devi1, Chinmaya Pani3, Amitabh Jena4
1 Department of Pathology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha, India
2 Department of Surgery, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha, India
3 Department of Medical Oncology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha, India
4 Department of Surgical Oncology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha, India
|Date of Web Publication||13-Jun-2017|
Department of Pathology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Patnayak R, Choudhuri R, Samal D, Mahapatra D, Devi K, Pani C, Jena A. Primary thyroid lymphoma – An uncommon entity. J NTR Univ Health Sci 2017;6:140-1
|How to cite this URL:|
Patnayak R, Choudhuri R, Samal D, Mahapatra D, Devi K, Pani C, Jena A. Primary thyroid lymphoma – An uncommon entity. J NTR Univ Health Sci [serial online] 2017 [cited 2020 Apr 10];6:140-1. Available from: http://www.jdrntruhs.org/text.asp?2017/6/2/140/208008
Primary thyroid lymphoma (PTL) is an uncommon tumor. It constitutes 2–8% of all thyroid malignancies and 1–2% of all extranodal lymphomas., They typically affect middle to old aged females. Most PTLs are of B and T-cell non-Hodgkin lymphoma. PTLs usually affect patients with long standing Hashimoto's thyroiditis. The present case is one such case of PTL diagnosed by histopathology with aid of immunohistochemistry.
A 45-year-old female presented to the surgery outpatient department with complaints of dysphagia and sudden increase in the size of thyroid swelling since last one month. There was no history of pain, change in voice, difficulty in deglutition or breathing, cold or heat intolerance, change in appetite, and palpitations. The patient complained of having this swelling since 2 years.
On examination, a diffuse midline neck swelling measuring 4 × 3 cm was noted which moved with deglutition. No palpable lymph nodes were found. Her serum T3 and T4 and anti-TPO levels were within normal range, whereas thyroid stimulating hormone (TSH) and calcium were raised. She underwent fine needle aspiration, which was reported as Hashimoto's thyroiditis.
Her routine laboratory examination was within normal limit. Total thyroidectomy with level II lymph node dissection was done. Cut section of the thyroidectomy specimen showed fleshy areas [Figure 1]a.
|Figure 1: (a) Cut section of thyroidectomy specimen showing fleshy areas. (b) Thyroid follicles, sheets of lymphoid cells, and lymphoepithelial lesion (H and E, ×100). (c) Diffuse sheets of lymphoid cells (H and E, ×100). (d) Diffuse CD20 positivity highlighting lymphoepithelial lesion (immunohistochemistry ×400)|
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Microscopically, the thyroid parenchyma was diffusely infiltrated by sheets of lymphoid cells. There was presence of lymphoepithelial lesion along with increased mitotic activity [Figure 1]b and [Figure 1]c. The adjacent thyroid showed features of Hashimoto's thyroiditis. The level II cervical lymph nodes showed reactive lymphadenitis.
Immunohistochemistry showed diffuse CD20, focal Bcl2 positivity whereas CD3, CD5, CD10, and CD23 were negative [Figure 1]d. Ki-67 labelling index was 40%.
The case was diagnosed as non-Hodgkin's lymphoma thyroid of mucosa-associated lymphoid tissue (MALT) lymphoma.
Her postoperative course was uneventful. Subsequently, her bone marrow examination did not show any lymphomatous involvement. The patient was planned for chemotherapy.
Primary thyroid lymphoma is an uncommon condition affecting the thyroid gland and the locoregional lymph nodes. Primary disease at other locations should be ruled out before diagnosing PTL. PTL patients are in older age group (median age being 60 years). PTL is limited to thyroid and usually originates in the setting of autoimmune thyroiditis. In comparison, secondary thyroid lymphoma, where the thyroid is secondarily affected by lymphoma, affect the middle-aged population (median age being 42 years). Secondary thyroid lymphoma patients present with disseminated disease and without complaints of thyroiditis.
The present patient did not have lymph node enlargement, and the cervical nodes included with the thyroidectomy specimen showed reactive hyperplasia. Thyroid lymphomas clinically and prognostically can be distinguished into two subtypes – diffuse large B-cell lymphoma (DLBCL) and MALT lymphoma. DLBCL is more common subtype (70%) and has a more aggressive clinical course. On the other hand, MALT lymphoma constitutea 6–27% of thyroid lymphomas. These have relatively indolent course with the underlying Hashimoto's thyroiditis.
Preoperative imaging diagnosis of PTL is difficult as the radiologic images, such as cross-sectional imaging (computed tomography/magnetic resonance imaging) or positron emission tomography do not often exhibit typical features. Recently, Wei et al. described PTLs as diffusive mass type with marked hypoechogenecity on conventional ultrasonography (US) and diffusive homogeneous enhancement pattern on contrast enhancing US (CEUS).
Fine needle aspiration plays an essential tool in the management of thyroid diseases. There are many reports of FNA diagnosis of PTL.,, The differential diagnosis for DLBCL is anaplastic thyroid carcinoma and for MALT lymphoma includes Hashimoto's thyroiditis. Cytological diagnosis of MALT lymphoma is often difficult because of the heterogenous population. The present case is an example of that difficulty.
In a study by Amani, frequent lymphoepithelial lesions and uniform CD20 positivity were reported in PTL. The clues towards the histopathological diagnosis of PTL in the current case were presence of lymphoepithelial lesion and sheets of CD20 positive lymphoid cells.
Different management modalities for PTLs include surgery, chemotherapy, radiotherapy, or combination treatment. After surgery, radiotherapy alone is sufficient for stage I and II low-grade thyroid lymphoma. Combination chemotherapy or adequate chemotherapy followed by radiotherapy is required in high-grade thyroid lymphoma. According to the experience of a UK lymphoma treatment centre, 5-year survival rates for DLBCL, MALT lymphoma, and indolent B-cell lymphoma NOS were 45%, 62%, and 75%, respectively. The median overall survival of all histological subtypes was 5.7 years.
This is another case of primary thyroid lymphoma adding to the existing literature.
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Conflicts of interest
There are no conflicts of interest.
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