Can a follicular neoplasm of the thyroid cause fever?

Follicular Neoplasm of the Thyroid and Fever

Follicular neoplasm of the thyroid does not typically cause fever as a presenting symptom. Fever is not a characteristic clinical manifestation associated with follicular thyroid neoplasms based on available evidence.

Understanding Follicular Neoplasms

Follicular neoplasms represent a heterogeneous group of thyroid lesions that include:

• Benign follicular adenomas 1
• Follicular carcinomas 1, 2
• Follicular variant of papillary carcinoma 1, 3
• Hürthle cell neoplasms (often included in this category) 1

These lesions are typically discovered during evaluation of a thyroid nodule, with diagnosis initially made through fine-needle aspiration (FNA) biopsy 4, 1.

Clinical Presentation of Follicular Neoplasms

Follicular neoplasms typically present with:

• Asymptomatic thyroid nodule(s) detected on routine physical examination 4
• Palpable thyroid mass 4
• No systemic symptoms like fever 4

The NCCN guidelines and other authoritative sources do not list fever among the presenting symptoms of follicular neoplasms 4.

Symptoms That Should Raise Concern

While follicular neoplasms themselves don't cause fever, certain thyroid malignancies may present with more aggressive symptoms:

• Anaplastic thyroid carcinoma may present with rapidly enlarging neck mass, dyspnea, dysphagia, neck pain, hoarseness, and other local symptoms, but fever is not typically mentioned 4
• Medullary thyroid carcinoma presents with a solitary nodule but without fever as a characteristic feature 4

Differential Considerations When Fever is Present

If a patient with a follicular neoplasm presents with fever, consider:

• Concurrent infection unrelated to the thyroid lesion 4
• Possible thyroiditis (inflammatory condition) rather than neoplasm 4
• Advanced malignancy with metastatic disease, though fever would still be uncommon 2, 3
• Other systemic conditions that may cause fever coincidentally 4

Diagnostic Approach for Follicular Neoplasms

The standard diagnostic approach for follicular neoplasms includes:

• Fine-needle aspiration (FNA) biopsy of the nodule 4, 5
• Cytologic examination categorizing the specimen (follicular neoplasm is one category) 4
• Diagnostic thyroid lobectomy and isthmusectomy for definitive diagnosis 1, 2

Importantly, the diagnosis of follicular carcinoma versus adenoma cannot be made on FNA alone, as it requires evidence of capsular or vascular invasion seen on permanent histology 1, 6.

Clinical Implications

When evaluating a patient with a thyroid nodule diagnosed as follicular neoplasm:

• Absence of fever is the expected presentation 4
• Presence of fever should prompt investigation for other causes 4
• Risk factors for malignancy in follicular neoplasms include male gender, nodule size ≥3 cm, and age ≥40 years 5
• Approximately 20% of follicular neoplasms prove to be malignant 1

Conclusion

Follicular neoplasms of the thyroid, whether benign or malignant, do not characteristically cause fever. If a patient with a follicular neoplasm presents with fever, clinicians should investigate for other etiologies of the fever rather than attributing it to the thyroid lesion.