Thyroid Lymphoma 101

Lymphoma of the thyroid gland may present with painless swelling in the neck due to an enlarged thyroid gland, or goiter.

Lymphoma is a blood cancer that affects the lymphocytes, a kind of white blood cell. The two main kinds of lymphoma are Hodgkin’s lymphoma, or HL, and non-Hodgkin’s lymphoma, or NHL. The majority of both NHL and HL are nodal lymphomas, meaning they originate in the lymph nodes. It’s possible, however, for lymphomas to arise almost anywhere.

When Lymphoma Starts Outside the Lymph Nodes

When lymphoma is believed to have originated outside the lymph nodes, it’s called extranodal lymphoma, or more precisely, primary extranodal lymphoma.

Primary extranodal lymphoma is much more common in NHL than in Hodgkin’s lymphoma. Up to 33 percent of all NHL is considered primary extranodal lymphoma. The most frequent site of primary extranodal lymphoma is in the gastrointestinal tract, and almost all of these are NHL.

When Lymphoma Starts in the Thyroid Gland

Primary thyroid lymphoma, or PTL, is a rare extranodal lymphoma -- and a rare cancer to occur in the thyroid gland. It is almost always NHL. Primary thyroid Hodgkins disease is extremely rare. PTL comprises only about five percent of all thyroid cancers and less than three percent of all extranodal lymphomas.

A Danish study estimated the annual incidence rate to be 2 per million persons, with 4 females for every 1 male affected. Other studies have also shown a higher frequency of thyroid lymphoma in women. On average, age at the time of diagnosis was between 65 and 75 years. Males, however, were affected five to 10 years earlier than females.

In a French study that looked back at 26 people with thyroid lymphoma, six different subtypes of lymphoma were seen:

  • 50 percent had diffuse large B cell lymphoma, or DLBCL
  • 23 percent had mucosa-associated lymphoid tissue or MALT lymphoma
  • 12 percent had follicular lymphoma
  • The rest were determined to be Hodgkin's disease, small lymphocytic lymphoma, and Burkitt's lymphoma.

    In other studies, DLBCL has been reported to account for up to 70 percent of PTLs.

    Symptoms and Warning Signs

    The most common thing that brought people with thyroid lymphoma to medical attention in these studies was a rapidly enlarging, painless swelling of the neck resulting from the enlargement of the thyroid gland -- a condition referred to as goiter.

    Most were without symptoms related to a thyroid hormone condition, although some had hypothyroidism – abnormally low thyroid gland activity.

    Other symptoms such as difficulty breathing, trouble swallowing and a hoarse voice can result from the growing cancerous mass putting pressure on the nearby structures -- the windpipe and esophagus.

    Enlarged lymph nodes in the neck are present in most cases.

    The so-called B symptoms, such as weight loss and night sweats, are less common, reported in about 20 percent of patients.

    Treatments

    Multi-modal therapy means that the cancer is treated using different methods, which may include chemotherapy, external beam radiation therapy and surgery.

    Cytotoxic chemotherapy involves the use of agents that kill the cancer cells. External beam radiation therapy focuses radiation to fight tumor cells and surgery can be performed to remove tumors and structures involved with the cancer.

    Outcomes

    Treatment and prognosis depends on what kind of immune cells gave rise to the primary thyroid lymphoma. The two most common kinds are covered below.

    Diffuse large B-cell lymphoma, or DLBCL:

    These represent about 70 percent of the pie. There are more favorable and more aggressive subtypes even within this kind of B-cell lymphoma, but response to treatment can be quite good.

    A study looking at the use of multimodal therapy for DLBCL described a 5-year overall survival rate of 90 percent for localized stage thyroid diffuse large B-cell lymphoma.

    Pure mucosa-associated lymphoid tissue, or MALT lymphoma:

    These represent about 30 percent of the pie. MALT lymphomas in the thyroid are thought to have similar origins to MALT lymphomas in the gastrointestinal tract, where they occur more commonly.  MALT lymphoma of the thyroid follows a relatively benign and slow growing course and is more likely to be found at an earlier stage, with a better response to treatment, but these malignancies can transform into more aggressive disease.

    Sources and Background - Primary Thyroid Lymphoma

    Walsh S, Lowery AJ, Evoy D, McDermott EW, Prichard RS. Thyroid Lymphoma: Recent Advances in Diagnosis and Optimal Management Strategies. The Oncologist. 2013;18(9):994-1003.

    Katna R, Shet T, Sengar M, et al. Clinicopathologic study and outcome analysis of thyroid lymphomas: Experience from a tertiary cancer center. Head Neck. 2013;35:165–171.

    Thieblemont C, Mayer A, Dumontet C, et al. Primary thyroid lymphoma is a heterogeneous disease. J Clin Endocrinol Metab. 2002;87:105–111.

    Niitsu N, Okamoto M, Nakamura N, et al. Clinicopathologic correlations of stage IE/IIE primary thyroid diffuse large B-cell lymphoma. Ann Oncol. 2007;18:1203–1208.

    Rawal A, Finn WG, Schnitzer B, et al. Site-specific morphologic differences in extranodal marginal zone B-cell lymphomas. Arch Pathol Lab Med. 2007;131:1673–1678.

    Pedersen RK, Pedersen NT. Primary non-Hodgkin's lymphoma of the thyroid gland: A population based study. Histopathology. 1996;28:25–32.

    Continue Reading