Primary thyroid lymphoma: Difference between revisions
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Revision as of 16:06, 8 September 2017
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]
Overview
Thyroid lymphomas may be classified according to type of cells into 6 subtypes: non–Hodgkin's B-cell lymphomas, Hodgkin's lymphoma, diffuse large B-cell lymphoma with marginal zone, diffuse large B-cell lymphoma without marginal zone, MALT lymphoma, and follicular lymphoma. Thyroid lymphoma is a rare malignant tumor constituting 1% to 2% of all thyroid malignancies and less than 2% of lymphomas.. BRAF and NRAS mutations are asssociated with thyroid lymphoma. Thyroid lymphoma is rare with an incidence of 1-2 per 100,0000. The factors of poor prognosis for patients with thyroid lymphoma are advanced stage of the tumor, large size (>10 cm) as well as spreading to mediastinum. The overall survival for primary thyroid lymphoma is 50% to 70%, ranging from 80% in stage IE to less than 36% in stage IIE and IVE in 5 years. Symptoms of thyroid lymphoma include painless rapidly growing neck mass, hoarseness, and difficulty in swallowing. Neck CT scan may be helpful in the diagnosis of thyroid lymphoma. Findings on CT scan suggestive of thyroid lymphoma is hypodense or heterogenous enhancement in the thyroid gland. Biopsy may be helpful in the diagnosis of thyroid lymphoma. Findings on biopsy suggestive of thyroid lymphoma include lymphoepithelial leision and lymphocytes. Combined modality therapy is the most common approach for the initial treatment of thyroid lymphomas. The CHOP regimen (cyclophosphamide, doxorubicin, vincristine and prednisone) has been showed high effectiveness for many types of thyroid lymphoma. However, it is suggested to perform radiation therapy only for MALT lymphoma resulting a 96% complete response, with only a 30% relapse rate. Surgical treatment might be performed for patients with thyroid lymphoma in addition to chemotherapy and radiation, particularly for MALT lymphoma.
Classification
Thyroid lymphomas may be classified according to type of cells into 6 subtypes: non–Hodgkin's B-cell lymphomas, Hodgkin's lymphoma, diffuse large B-cell lymphoma with marginal zone, diffuse large B-cell lymphoma without marginal zone, marginal zone В-cell lymphoma of mucosa-associated lymphoid tissue, and follicular lymphoma.
Pathophysiology
- Thyroid lymphoma is a rare malignant tumor constituting 1% to 2% of all thyroid malignancies and less than 2% of lymphomas.
- The thyroid may be affected primarily or secondary to lymphoma elsewhere.
- There is increased risk with chronic inflammatory conditions.
Genetics
- BRAF and NRAS mutations are asssociated with thyroid lymphoma.
- MAPK pathway mutations are associated with B cell thyroid lymohoma.[1]
Associated Conditions
Gross Pathology
- Variable size
- Rubbery mass with fish flesh appearance
Microscopic Pathology
- On microscopic histopathological analysis, characteristic findings of thyroid lymphoma are:
- Lymphoepithelial lesion
- Plasma cells
- Thyroid parenchyma displaced by lymphocytes
Epidemiology and Demographics
Incidence
- Thyroid lymphoma is rare with an incidence of 1-2 per 100,0000
Age
- It typically presents between 50-70 years of age
Gender
- Females are more commonly affected with anaplastic thyroid cancer than males. The females to male ratio is approximately 3 to 1.
Natural History, Complications and Prognosis
- The factors of poor prognosis for patients with thyroid lymphoma are advanced stage of the tumor, large size (>10 cm) as well as spreading to mediastinum. The overall survival for primary thyroid lymphoma is 50% to 70%, ranging from 80% in stage IE to less than 36% in stage IIE and IVE in 5 years.
Complications
- Vocal cord paralysis
- Dyspnea
- Dysphagia
- Metastasis
Prognosis
- Prognosis depends on the histological grade of the tumor
- MALT lymphoma have better prognosis with a slower progressive course
- Diffuse large cell lymphomas have worse prognosis and aggressive course
- 5 year survival rate varies between 50-60%[2]
Staging
- Staging of thyroid lymphoma is showed in the table below
| Stage | Characteristics |
|---|---|
| IE | Lymphoma is located within the thyroid |
| 2E | Lymphoma is located within the thyroid and regional lymph-nodes |
| 3E | Lymphoma is located at both sides of diaphragm |
| 4E | Dissemination of lymphoma |
Diagnostic Criteria
Thyroid lymphoma shows a diagnostic and therapeutic challenge in many cases, because some manifestation patterns are similar to anaplastic thyroid carcinoma (ATC). Performance of fine needle aspiration biopsy has helped to distinguish these two entities preoperatively.
History
A directed history should be obtained to ascertain
Symptoms
Physical Examination
Throat
- Rapidly growing painless mass in the neck
- Lymphadenopathy
CT
- Goitre, which is hypodense to adjacent muscle
- Heterogeneous enhancement but still less than adjacent muscle
MRI
- T1/T2: iso- to hyperintense
- Pseudocapsule may be present
Echocardiography or Ultrasound
- Three patterns have been described: nodular (hypoechoic mass), diffuse (mixed echotexture) or mixed. Calcifications are uncommon.
Biopsy
Biopsy may be helpful in the diagnosis of thyroid lymphoma. Findings on biopsy suggestive of thyroid lymphoma include lymphoepithelial leision and lymphocyte.
Treatment
Pharmacotherapy
Combined modality therapy is the most common approach for the initial treatment of thyroid lymphomas. The CHOP regimen (cyclophosphamide, doxorubicin, vincristine and prednisone) has been showed high effectiveness for many types of thyroid lymphoma. However, it is suggested to perform radiation therapy only for MALT resulting a 96% complete response, with only a 30% relapse rate.
Acute Pharmacotherapies
Chronic Pharmacotherapies
Surgery and Device Based Therapy
- Surgical treatment might be performed for patients with thyroid lymphoma in addition to chemotherapy and radiation, particularly for MALT lymphomas.
- Thyroidectomy (rarely)
- Radical left neck dissection
- Tracheostomy is indicated for vocal cord paralysis
References
- ↑ Aggarwal, Nidhi; Swerdlow, Steven H; Kelly, Lindsey M; Ogilvie, Jennifer B; Nikiforova, Mariana N; Sathanoori, Malini; Nikiforov, Yuri E (2012). "Thyroid carcinoma-associated genetic mutations also occur in thyroid lymphomas". Modern Pathology. 25 (9): 1203–1211. doi:10.1038/modpathol.2012.73. ISSN 0893-3952.
- ↑ Hedhili, F.; Kedous, S.; Jbali, S.; Attia, Z.; Dhambri, S.; Touati, S.; Chebbi, A. Goucha; El May, A.; Gritli, S. (2015). "Primary thyroid lymphoma: Case report and review of the literature". Egyptian Journal of Ear, Nose, Throat and Allied Sciences. 16 (2): 171–173. doi:10.1016/j.ejenta.2015.05.002. ISSN 2090-0740.