Recurrent Acute Suppurative Thyroiditis Secondary to Pyriform Sinus Fistula Due to Staphylococcus Sciuri with Subclinical Hyperthyroidism in an Adult. A Diagnostic and Therapeutic Challenge.

Background: Acute suppurative thyroiditis (AST) caused by pyriform sinus fistula (PSF) is a rare condition in adults. PSF is a congenital malformation that can cause an infection of the thyroid gland, usually located on the left side. AST presents with symptoms similar to respiratory infections, which can make it difficult to diagnose. It is essential to consider PFS as a differential diagnosis due to its relationship with the recurrence of thyroid abscesses.

Case report: We report the case of a 32-year-old woman who presented with neck pain and fever, initially mistaken for an upper respiratory infection. After 3 weeks, she was diagnosed with AST with an abscess in the left thyroid lobe. Drainage and initial antibiotic treatment (metronidazole and clindamycin) improved her condition. However, due to non-compliance with medical follow-up, the patient suffered a recurrence of the abscess and required a left thyroid lobectomy. The culture identified multidrug-resistant Staphylococcus sciuri and the patient was finally referred for a successful fistulectomy.

Conclusion: AST due to PSF is uncommon in adults, with few documented cases. Initial treatment includes antibiotics and surgical drainage, although recurrence can occur if the risk factor is not eliminated. In this case, failure to comply with medical follow-up contributed to the recurrence. It is crucial to identify PSF as a causative factor early on and to carry out adequate follow-up to avoid serious complications.

Learning points: Thyrotoxicosis can occur in up to 42% of cases of acute suppurative thyroiditis, making it less relevant to differentiate it from other causes of thyroiditis.In adults with no obvious risk factors, congenital malformations should be considered, especially when the condition affects the left lobe.To avoid recurrences, it is necessary to evaluate the pyriform sinus in any age group and patient adherence to medical instructions is essential.