Thyroid primary and metastatic malignant tumours of poor prognosis may mimic subacute thyroiditis - time to change the diagnostic criteria: case reports and a review of the literature

Abstract

Background: The diagnosis of subacute thyroiditis (SAT) is based mainly on the presence of painful thyroid goitre and a significant increase in erythrocyte sedimentation rate (ESR). Proceeding according to these diagnostic criteria may lead to an incorrect diagnosis and treatment. Extremely dangerous is the situation when the diagnosis of SAT is erroneously made based on criteria other than ultrasound (US) image and fine needle aspiration biopsy (FNAB), which leads to delayed diagnosis of malignant tumour with poor prognosis. Case presentation: Five patients with typical SAT symptoms are presented. In all of them, anaplastic thyroid cancer or metastatic thyroid tumours were finally diagnosed as the cause of the initial symptoms resembling SAT. Most of the patients were initially misdiagnosed and the proper diagnosis of malignancy was delayed. Conclusions: The authors have proposed the new diagnostic criteria for SAT, and strongly suggest that thyroid gland US should be included in the main criteria of SAT diagnosis, together with FNAB result excluding the presence of malignant tumour.

Time-Lag Between Symptom Onset and Diagnosis of Subacute Thyroiditis – How to Avoid the Delay of Diagnosis and Unnecessary Overuse of Antibiotics

“…Suppressed TSH and elevated FT4 additionally confirm SAT diagnosis and evidence against infection. Even if hormonal tests are normal, but palpable thyroid abnormailities are present, the patient should obligatory be referred to an endocrinologist, because such symptoms require differentiating between SAT, acute purulent thyroiditis or even primary or metastatic thyroid malignancy [11].…”

“…The diagnosis of SAT was based on the diagnostic criteria recently proposed by our team [2,11] . These criteria are as follows: elevation of ESR (or at least CRP) plus hypoechoic area/areas with blurred margin and decreased vascularization in US plus FNAB confirmation of SAT, or at least FNAB exclusion of malignancy, plus at least one of the following: hard thyroid swelling and/or pain and tenderness of the thyroid gland/lobe and/ or elevation of serum FT4 and suppression of TSH and/ or decreased radioiodine uptake (RAIU).…”

Subacute Thyroiditis is Associated with HLA-B*18:01, -DRB1*01 and -C*04:01—The Significance of the New Molecular Background

“…The diagnosis of SAT was based on the diagnostic criteria recently proposed by our team [23]. These criteria are as follows: elevation of ESR (or at least CRP) plus hypoechoic area/areas with blurred margins and decreased vascularization according to ultrasonography; cytological confirmation of SAT, or at least cytological exclusion of malignancy; plus at least one of the following: hard thyroid swelling and/or pain and tenderness of the thyroid gland/lobe, elevation of serum free thyroxine (FT4) and suppression of thyroid stimulating hormone (TSH), and decreased radioiodine uptake (RAIU).…”

Subakute Thyreoiditis und akute suppurative Thyreoiditis

“…In solchen Fällen sollte die Indikation zu einer Feinnadelpunktion als ambulantes, einfaches und risikoarmes Verfahren sehr großzügig gestellt werden [25]. Aufgrund der möglichen Verwechslung mit malignen Prozessen wird von einigen Autoren bei der Diagnosestellung eine verpflichtende Feinnadelpunktion zum Ausschluss solcher Geschehen gefordert [26]. Das typische zytologische Bild nach Feinnadelpunktion einer SAT zeigt granulomatöse Infiltrate sowie Riesenzellen wie bei einer viralen Infektion [1].…”