Hyperthyroidism due to lymphoma involving the thyroid gland in a patient with acquired immunodeficiency syndrome: case report and review of the literature

Infiltration of the thyroid gland by non-thyroid malignancy: A literature review reveals this to be an unusual cause of hyperthyroidism

Background

Non-thyroid malignancies that metastasize to the thyroid gland are relatively rare. At one end of the spectrum they may only be identified at the time of autopsy. At the other extreme, they may be identified during the evaluation of a progressive malignancy. Most patients who are identified as having metastases to their thyroid gland are euthyroid, but some patients may have associated hypothyroidism or hyperthyroidism. This review examines cases of hyperthyroidism associated with metastases affecting the thyroid gland.

Results

Twenty four articles describing 26 cases of malignancy-associated hyperthyroidism were identified, with the cases presenting with features suggestive of a thyroiditis and with goiter. The solid malignancies (19 cases) were mostly breast and lung cancer. Hematologic malignancies (7 cases) were also reported with a similar thyroiditis-like presentation. Patients underwent the traditional work-up for a thyroiditis, but frequently underwent other radiographic studies, in addition to radioactive iodine imaging, and frequently also underwent thyroid biopsy. The course in most patients (22/26 cases) was progression from hyperthyroidism to hypothyroidism, as the underlying malignancy progressed or thyroidectomy was performed, or the patient succumbed to their malignancy. Some patients (4 cases) became euthyroid with successful treatment of their malignancy. A subset of patients (5 cases) initially presented with severe thyrotoxicosis. Many affected patients succumbed to their underlying malignancy.

Conclusion

Malignancy-associated hyperthyroidism has a similar underlying mechanism to subacute thyroiditis, in so much as there is damage or destruction of thyroid tissue. In cases of subacute thyroiditis this damage is self-limited, and there is recovery of thyroid function. In some cases of thyroiditis associated with malignancy there may be thyroid gland recovery as the underlying malignancy is treated and controlled. However, if the malignancy progresses, eventual hypothyroidism is likely to ensue.

Thyroid abnormalities

Thyroid abnormalities and nonthyroidal illness complicate human immunodeficiency virus (HIV) infection. Among the effects that result from HIV and other opportunistic infections, distinctive features of HIV infection include early lowering of reverse tri-iodothyromine (T3) levels, with normal free T3 levels. Later, some patients develop an isolated low free thyroxine level. After highly active antiretroviral therapy, the immune system reconstitutes in a way that leads to dysregulation of the autoimmune response and the appearance of Graves disease in 1% to 2% of patients. Opportunistic thyroid infections with unusual organisms are most commonly asymptomatic, but can lead to acute or subacute thyroiditis.

Burkitt-like lymphoma infiltrating a hyperfunctioning thyroid adenoma and presenting as a hot nodule

BACKGROUND

Most solitary hyperfunctiong regions on thyroid scan consist of benign tissue. Here we report a patient with a Burkitt-like lymphoma that was infilterated into a region containing a hyperfunctioning nodule.

SUMMARY

A 56-year-old man was referred to our Endocrine Unit in May 2009 due to the incidental discovery of a large left thyroid lobe nodule by a computed tomography study. This had been performed to search for a primitive tumor in a patient with bone metastasis. He was clinically and biochemically thyrotoxic with no evidence of humoral thyroid autoimmunity. The nodule had a dyshomogenous appearance at neck ultrasonography, with multiple hypoechogenic areas and calcifications. (99m)-Technetium thyroid scintiscan revealed a hot nodule with suppression of the contralateral lobe. Fine-needle aspiration cytology indicated the presence of neoplastic cells not of thyroid origin. Remission of hyperthyroidism was obtained with methimazole, and the patient was submitted to left lobe thyroidectomy and istmectomy. Histological analysis of the surgical specimen led to a diagnosis of Burkitt-like large B-cell lymphoma harbored within a thyroid adenoma. After further staging, the final diagnosis was stage IV E Burkitt-like lymphoma with the involvement of the bone and the thyroid. This is the first description of an aggressive Burkitt-like lymphoma that infiltrated an hyperfunctioning thyroid adenoma, thus presenting as a hot nodule at thyroid scintiscan. In our patient there was no humoral or histological evidence of thyroid autoimmunity, thus suggesting a metastatic seeding of the lymphoma within the hyperfunctioning thyroid nodule.

CONCLUSIONS

Involvement of the thyroid gland by Burkitt-like lymphoma is extremely rare as is close localization of malignancy and a hyperfunctioning thyroid nodule. As highlighted by the present report, performing fine-needle aspiration cytology should be always considered in the clinical context of a metastatic disease of unknown origin or when there are ultrasonography signs suggesting malignancy, even when the nodule is hyperfunctioning.

Viruses and thyroiditis: an update

Viral infections are frequently cited as a major environmental factor involved in subacute thyroiditis and autoimmune thyroid diseases This review examines the data related to the role of viruses in the development of thyroiditis.

Our research has been focused on human data. We have reviewed virological data for each type of thyroiditis at different levels of evidence; epidemiological data, serological data or research on circulating viruses, direct evidence of thyroid tissue infection. Interpretation of epidemiological and serological data must be cautious as they don't prove that this pathogen is responsible for the disease. However, direct evidence of the presence of viruses or their components in the organ are available for retroviruses (HFV) and mumps in subacute thyroiditis, for retroviruses (HTLV-1, HFV, HIV and SV40) in Graves's disease and for HTLV-1, enterovirus, rubella, mumps virus, HSV, EBV and parvovirus in Hashimoto's thyroiditis. However, it remains to determine whether they are responsible for thyroid diseases or whether they are just innocent bystanders. Further studies are needed to clarify the relationship between viruses and thyroid diseases, in order to develop new strategies for prevention and/or treatment.

A Variant of Thyrotoxicosis Associated with Chronic Thyroiditis Characterized by Prolonged Fever, Absence of Anti-Thyroidal Antibodies, and Favorable Response to Naproxen

An unusual form of thyrotoxicosis due to chronic thyroiditis is described. A 78-year-old debilitated woman was admitted because of fever to 38 degrees C persisting for the previous 16 months, for which the antipyretic effect of diclofenac sodium and pranoprofen had been insufficient or transient. Intense accumulation of gallium-67 citrate in the thyroid gland provided an initial clue to the diagnosis of masked thyrotoxicosis as a cause of the fever, and naproxen (300 mg/d) eliminated the fever and flaring of thyrotoxicosis. Despite the absence of autoantibodies related to chronic thyroiditis, needle biopsy revealed destructive thyroiditis due to chronic lymphocytic thyroiditis. This case suggests a previously unrecognized variant of thyrotoxicosis due to chronic thyroiditis, that is, neither painless thyroiditis nor acute exacerbation of Hashimoto thyroiditis, and instead characterized by prolonged fever, nontender thyroid, absence of antibodies associated with autoimmune thyroiditis, and excellent response to naproxen.

Human immunodeficiency virus infection and the thyroid

Abnormalities of thyroid function are associated with a number of systemic conditions, including patients infected with human immunodeficiency virus (HIV). Most patients with early HIV infection and a stable body weight have normal thyroid function. Subtle abnormalities of a number of thyroid function tests have been reported during the early asymptomatic phase of HIV disease. These include an inappropriately normal triiodothyronine (T(3)) and reduced reverse triiodothyronine (rT(3)), and increased thyroxine-binding globulin (TBG) levels. Opportunistic infections involving the thyroid gland, neoplasms such as lymphoma and Kaposi's sarcoma, and medications can alter the thyroid function in individuals with more advanced HIV infection. If thyroid dysfunction is diagnosed in an HIV-infected patient, it should be treated in the usual manner. However, high index of suspicion and caution in the interpretation of thyroid function tests in patients with HIV disease are needed for optimal diagnosis and treatment.

Anaplastic pseudothyroiditis

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumours. It generally presents as a rapidly enlarging thyroid mass and produces local symptoms associated with mass effect. One of the very rare presentations of ATC is thyrotoxicosis. We report a patient with ATC whose course was complicated by severe thyrotoxicosis. His symptoms were controlled with beta-blockers. Two weeks into hospitalization, the patient became hypothyroid. Histopathology showed destruction of the normal thyroid follicles by the invasion of the tumour. As this form of thyrotoxicosis resembles various thyroiditides, we hereby refer this condition as "anaplastic pseudothyroiditis".

Severe thyrotoxicosis induced by thyroid metastasis of lung adenocarcinoma: a case report and review of the literature

A 50-year-old woman who had undergone lung lobectomy because of lung adenocarcinoma presented with thyrotoxicosis, neck swelling, and cervical lymphadenopathy one month after the operation. The total serum triiodothyronine (T3) and thyroxine (T4) levels were markedly elevated to 514 ng/dL and 26.4 microg/dL, respectively, and serum thyrotropin (TSH) was suppressed to less than 0.005 microU/mL. Although the thyroid gland had been normal before surgery, chest computed tomography (CT) scan revealed a markedly enlarged thyroid gland only 1 month after surgery. 123I uptake for 24 hours was suppressed to 4% in the thyroid gland with no uptake elsewhere including the lung. Fine-needle aspiration cytology (FNAC) of the thyroid showed invasion of poorly differentiated adenocarcinoma cells, cytologically identical to the cells obtained from sputum and those infiltrating the resected sections of the lung adenocarcinoma. Immunohistochemical studies of resected lung tissues did not show positive staining for thyroglobulin, carcinoembryonic antigen (CEA), or surfactant protein A. Clinically, the thyrotoxicosis had spontaneously improved, followed by a hypothyroid state with shrinkage of the thyroid gland after chemotherapy. Despite repeated chemotherapy and the administration of thyroxine for hypothyroidism, the patient died of respiratory failure 9 months after the onset of thyrotoxicosis. From these findings and the clinical course, thyroid metastasis, developing subacutely from lung adenocarcinoma, was diagnosed. We speculate that aggressive invasion of tumor cells into the thyroid gland resulted in highly destructive thyrotoxicosis.