Teaching Case

57 years-old male with a clinical history of 1 month consisting in night fever, sweating, weight loss and flushing crisis

US: Enlarged thyroid gland including both lobes with ill-defined hypoechoic lesions of posterior-basal predominance. No nodules were identified(Fig 1). Doppler study showed increased signal in the thyroid gland and less signal at the lesions(Fig 2).
Multiple lymph nodes were identified(Fig 1d).

IMAGING PERSPECTIVE[1, 2, 3, 4, 5]
-Thyroid scintigraphy: In patients with no clear clinical manifestations, scintigraphy may be a good point to start, as we can screen Graves' disease. Contrary to Graves' disease, SGT shows a cold thyroid gland.

-US: Patchy or focal ill-defined hypoechoic lesions associated with diminished blood flow at color Doppler are the classic US findings. Some authors compare the ill-defined lesions with the image that lava flow makes. It may involve one lobe or both.
Also heterogeneous thyroid gland with diminished Doppler signal should raise the suspicion for SGT.

BACKGROUND[1, 2, 3, 4, 5, 7]

Subacute granulomatous thyroiditis(SGT) is a self-limited inflammatory disease. It has a triphasic clinical course of hyperthyroidism, hypothyroidism, and return to normal thyroid function in most patients.
SGT has a low incidence (12.1 per 100, 000 per year) with a female sex predominance (4:1) being the middle-aged women the most affected. It is believed to be a postviral condition. However, HLA-Bw35 has been identified with strong association(>70% of patients).
The normal thyroid tissue it's damaged and then replaced by non-caseating granulomas, all with chronic inflammation infiltration.

CLINICAL PERSPECTIVE[1, 2, 4, 6]

SGT diagnosis is made with a combination of classic clinical symptoms and laboratory parameters (suppressed TSH, elevated ESR). Most frequent symptoms include neck pain, hypermetabolism, low grade fever and palpitations among others. Usually a previous viral infection may be documented.
Although the diagnosis is clinical, imaging with US is a useful tool for diagnosing and monitoring thyroid pathology. Ultrasound elastografy has nowadays a controversial paper.

TREATMENT AND OUTCOME[1, 2, 3, 8]

It is important to detect this pathology due to the self-limited course. Fine needle aspiration is not necessary.
The treatment is based on anti inflammatory therapy, if NSAIDs are not enough, corticosteroid treatment can be performed. Return to normal thyroid function is found in most patients (90%).
Control US usually shows the normalisation of the gland size and pattern.

The treatment of our patient was started with NSAIDs with no effect after 1 week. The therapy was changed to corticosteroid treatment with good effect. Nowadays the patient is asymptomatic.

TAKE HOME MESSAGE:

SGT is an acute inflamatory disease of the thyroid gland, middle-aged women most affected, with a self-limited triphasic course (hyperthyroidism, hypothyroidism and return to euthyroidism) . It has classic sonographics findings and a low radioactive iodine uptake. After anti-inflammatory therapy( NSAIDs or corticosteroids ) euthyroid outcome is found in most patients.

Written informed patient consent for publication has been obtained.