Endocrine Abstracts

Background: Acute Suppurative Thyroiditis (AST) is a rare condition due to the thyroid’s intrinsic defense mechanisms (1). However, it can be severe or even life-threatening, requiring urgent and proactive management (1,2). We report the case of an immunocompetent middle-aged woman in whom infection of thyroid metastases led to a diagnosis of metastatic pulmonary cancer classified as non-small cell lung cancer – not otherwise specified (NSCLC-NOS group).

Case presentation: A 57-year-old woman presented to the emergency department with a painful cervical mass developed over the preceding days, without evidence of airway compromise. Cervical ultrasound performed by the radiologist revealed a multinodular goiter, while chest X-ray demonstrated a previously unknown right apical pulmonary mass, subsequently considered suspicious on computed tomography (CT) imaging. The patient was urgently referred for an endocrinological evaluation the following day. Thyroid ultrasound confirmed the presence of several hypoechoic, heterogeneous, partially cystic thyroid masses, with internal or peripheral vascularity, of up to 2cm. Fine-needle aspiration (FNA) of the two largest nodules was performed (Figure 1), yielding a purulent fluid. Unfortunately, a pathogen could not be identified, likely due to prior antibiotic treatment for a suspected pulmonary infection a few days earlier. Subsequently, despite broad-spectrum antibiotic coverage, a CT-guided biopsy of the apical pulmonary mass was performed for both histopathological and microbiological analysis. 16S rRNA PCR testing identified Porphyromonas endodontalis, which was considered the likely pathogen responsible for both the pulmonary and thyroid abscesses, particularly considering prior dental procedures. The staging workup revealed the presence of multiple metastatic lesions involving the kidneys, peritoneum, adrenal glands, thyroid and muscles. Follow-up thyroid ultrasound after completion of antibiotic therapy showed progression of the thyroid masses (Figure 1). This was attributed to oncologic treatment failure, with evidence of progression of the metastatic disease, leading to the patient’s death within three months.

Discussion: Given a reported mortality rate ranging from 3.7 to 8.6% based on published reviews, AST requires a proactive management. Treatment combines drainage – either surgical or via FNA – with empirical antibiotic therapy, which generally includes penicillinase-resistant penicillin and β-lactamase inhibitors (2). Antifungal therapy should be considered in immunocompromised patients and antituberculosis treatment for patients from endemic areas (3). Although rare – accounting for 0.1-0.7% of thyroid pathologies (2-3) – AST should be suspected in cases of neck pain with fever, especially when local compressive symptoms are present and even more so in patients with predisposing factors such as immunosuppression, prior thyroid FNA, diabetes, pyriform sinus fistula, bacteremia, etc. (3) Much more rarely, AST has been reported in the context of underlying primary thyroid cancer, likely related to structural gland modifications (1,2). Regarding AST associated with thyroid metastases, only one case has been documented in which diagnosis of the primary cancer was suspected based on FNA of the thyroid mass (4). Destructive thyroiditis causing hyperthyroidism may be observed in AST, with variable frequency according to the literature. This can lead to diagnostic confusion, particularly with subacute thyroiditis, which represents one of the main differential diagnoses. Other differentials include infected thyroglossal duct cyst, lymphoma, deep vein thrombosis, abscess of adjacent neck tissue, etc. (3) Ultrasound performed by an experienced clinician remains the preferred initial diagnostic tool, typically revealing a heterogeneous iso- or hypoechoic mass, as observed in our case (Figure 1).

Figure 1: A and B: the two largest thyroid masses before FNA; C and D: progression of the same masses following antibiotic therapy, attributed to progression of the metastatic disease.

Conclusion: AST is a rare and potentially life-threatening thyroid condition. Infection of a primary neoplastic thyroid lesion is exceptional, whereas infection of a metastatic lesion within the thyroid gland has, to our knowledge, only once been reported in the literature as such.

Referencees: 1. Toschetti T, Parenti C, Ricci I, Addati I, Diona S, Esposito S, Street ME. Acute Suppurative and Subacute Thyroiditis: From Diagnosis to Management. J Clin Med. 2025 May 7;14(9):3233. 2. Paes JE, Burman KD, Cohen J, Franklyn J, McHenry CR, Shoham S, Kloos RT. Acute bacterial suppurative thyroiditis: a clinical review and expert opinion. Thyroid. 2010 Mar;20(3):247-55. 3. Lafontaine N, Learoyd D, Farrel S, Wong R. Suppurative thyroiditis: Systematic review and clinical guidance. Clin Endocrinol (Oxf). 2021 Aug;95(2):253-264 4. Dai L, Lin S, Liu D, Wang Q. Acute suppurative thyroiditis with thyroid metastasis from oesophageal cancer. Endokrynol Pol. 2020;71(1):106-107.