Primary Xanthogranulomatous Inflammation of Thyroid Presented as a Huge Neck Mass: A diagnostic Challenge

Introduction: Xanthogranulomatous inflammation (XGI) is an uncommon variant of chronic inflammation and a well-established pathological entity involving various organs and systems. The commonest site of XGI is the gall bladder and kidney. It is rare in the head and neck region. Only 13 cases have been reported in the head and neck region to date at different locations. The exact pathophysiology of XGI remains unexplained. It may be associated with trauma, post-surgery, infection, obstruction, defective lipid transport, and immunological disturbances, and is often confused with a malignant neoplasm. The conclusive diagnosis is made through histopathology. Case Report: We present a unique case of a huge neck mass measuring 25x25 cm in a 76-year-old patient who was diagnosed clinically and radiologically as a thyroglossal cyst and/or colloid goitre, respectively. On histopathological examination, the mass showed extensive XGI replacing the bilateral lobes of the thyroid parenchyma. The differentials included malakoplakia, tuberculosis, or metastatic cystic squamous cell carcinoma. Conclusion: To the best of my knowledge, this is the first reported case where the primary xanthogranuloma of the thyroid presented as a huge cystic neck mass in the absence of any congenital cysts, and the patient was both surgically naïve and non-diabetic. The histopathological examination is mandatory to rule out the possibility of other lesions. However, the pathophysiology is unexplained. Awareness of this inflammatory lesion is important to the pathologist and treating surgeon to prevent extensive surgery.