Diagnostic Value of Thyroid Ultrasound in Disseminated Fungal Infection. Case Report.

INTRODUCTION: Intrathyroidal nodules in pediatrics are less frequent than in adults. Infectious etiologies, particularly fungal, are rare but relevant in immunocompromised patients and can mimic neoplastic lesions. CASE REPORT: We report a 14-year-old female with a history of osteosarcoma; six months after oncologic treatment she was diagnosed with acute lymphoblastic leukemia. A cervical imaging study performed for central venous catheter placement revealed two left thyroid nodules interpreted as suspicious for malignancy. Fine-needle aspiration (FNA) was performed. Initial pathology was negative for neoplastic cells and demonstrated hyaline septate hyphae; subsequent microbiological evaluation identified Candida albicans. The patient received targeted antifungal therapy. DISCUSSION: This case illustrates that fungal thyroid infection can be present as a nodule suspicious for malignancy in pediatric oncology patients, even in the absence of overt neutropenia. FNA allowed identification of hyphae and guided microbiological workup, underscoring the usefulness of combining cytology, culture, and molecular techniques for etiologic diagnosis and appropriate management. CONCLUSION: In oncologic or immunocompromised patients presenting with a newly appearing thyroid nodule, especially when prior imaging was normal, infectious etiologies - including fungi - should be included in the differential diagnosis.