Overview
Definition:
Thyroid nodules in children are discrete lesions within the thyroid gland that are palpable or detected incidentally on imaging
While most are benign, the risk of malignancy is higher in pediatric populations compared to adults, necessitating careful evaluation.
Epidemiology:
Thyroid nodules are uncommon in children, with a prevalence of 0.2-1.8%
The incidence of malignancy among pediatric thyroid nodules is significantly higher, ranging from 25-50%, compared to 5-15% in adults
Factors associated with increased malignancy risk include a history of radiation exposure, family history of thyroid cancer, and rapid nodule growth.
Clinical Significance:
Prompt and accurate evaluation of pediatric thyroid nodules is crucial due to the elevated malignancy risk
Early detection of thyroid cancer in children can lead to timely and appropriate management, potentially improving long-term outcomes and reducing morbidity
This topic is highly relevant for pediatricians, endocrinologists, radiologists, and surgeons preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Painless neck mass or swelling
Rapidly growing neck mass
Hoarseness of voice due to recurrent laryngeal nerve involvement
Dysphagia or odynophagia if the nodule is large or infiltrative
Symptoms of hyperthyroidism or hypothyroidism are uncommon but possible
Neck pain or tenderness is more suggestive of inflammation or hemorrhage within the nodule.
Signs:
Palpable thyroid nodule(s) on physical examination
Nodules may be solitary or multiple, firm, or cystic
Associated cervical lymphadenopathy, especially if firm, fixed, or matted, raises suspicion for malignancy
Signs of vocal cord paralysis (e.g., hoarseness, stridor).
Diagnostic Criteria:
No specific diagnostic criteria for the nodule itself
Evaluation is guided by suspicion of malignancy based on risk factors, ultrasound features, and FNA results
The American Thyroid Association (ATA) guidelines for pediatric thyroid nodules emphasize a low threshold for biopsy in children with any palpable nodule.
Diagnostic Approach
History Taking:
Detailed history of radiation exposure (e.g., radiotherapy for other malignancies, Chernobyl fallout)
Family history of thyroid cancer, especially medullary thyroid carcinoma or multiple endocrine neoplasia (MEN)
History of rapid nodule growth, hoarseness, dysphagia, or symptoms of thyroid dysfunction
Previous neck surgery or biopsy
Age at presentation (younger age increases risk).
Physical Examination:
Careful palpation of the thyroid gland to assess nodule size, consistency (firm, hard, cystic), mobility, and presence of surrounding thyroid tissue abnormalities
Examination of cervical lymph nodes for enlargement, consistency, and mobility
Evaluation of vocal cord function by observing voice quality and, if possible, direct laryngoscopy.
Investigations:
Ultrasound of the thyroid is the primary imaging modality for initial assessment
Ultrasound features suggestive of malignancy include: microcalcifications, irregular margins, taller-than-wide shape, hypoechogenicity, extrathyroidal extension, and suspicious cervical lymph nodes
Color Doppler may show increased vascularity
Fine Needle Aspiration (FNA) biopsy is the gold standard for cytological evaluation
Thyroid function tests (TSH, free T4, free T3) should be performed to assess for functional status and rule out associated thyroid dysfunction
Other imaging like CT or MRI may be useful for assessing extent and relation to adjacent structures if malignancy is suspected
Radioiodine scan is typically reserved for cases where hyperthyroidism is suspected or to evaluate for metastatic disease.
Differential Diagnosis:
Benign nodules (adenomas, follicular adenomas, colloid nodules, thyroid cysts)
Thyroiditis (Hashimoto's, subacute)
Goiter (diffuse or multinodular)
Thyroid abscess
Lymphadenopathy of other etiology
Metastatic disease to the thyroid.
Ultrasound Risk Features
Microcalcifications:
Presence of punctate or linear echogenic foci within the nodule, highly suspicious for papillary thyroid carcinoma.
Hypoechogenicity:
Nodules that are significantly darker than the surrounding thyroid parenchyma are more likely to be malignant.
Irregular Margins:
Spiculated, lobulated, or ill-defined borders suggest infiltration and are concerning for malignancy.
Taller Than Wide Shape:
Nodules with anteroposterior dimension greater than their transverse dimension have a higher risk of malignancy.
Extothyroidism Extension:
Breaching of the thyroid capsule, indicating local invasion.
Suspicious Lymph Nodes:
Enlarged cervical lymph nodes with rounded shape, hypoechogenicity, absent fatty hilum, or cortical thickening.
Fine Needle Aspiration Fna
Indications For Fna:
All palpable thyroid nodules in children
Non-palpable nodules with suspicious ultrasound features (e.g., >1 cm and concerning features, or any size with highly suspicious features like microcalcifications).
Cytology Categories:
The Bethesda System for Reporting Thyroid Cytopathology is used: Non-diagnostic, Benign, Atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS), Follicular neoplasm or suspicious for follicular neoplasm (FN/SFN), Suspicious for malignancy, Malignant
High-risk categories (FN/SFN, Suspicious for malignancy, Malignant) warrant further surgical management.
Interpretation Challenges:
Distinguishing between follicular adenoma and follicular carcinoma solely on FNA cytology can be challenging (requires capsular or vascular invasion seen on histology)
AUS/FLUS category requires careful follow-up or repeat biopsy.
Biopsy Technique:
Ultrasound-guided FNA is preferred for accuracy and to sample specific areas identified as suspicious
Rapid on-site evaluation (ROSE) by a cytopathologist can improve specimen adequacy.
Management
Initial Management:
Based on ultrasound findings and FNA results
If FNA is benign and ultrasound features are low-risk, observation with serial ultrasound follow-up may be considered
If suspicious or malignant, surgical intervention is usually indicated.
Medical Management:
Primarily for managing underlying thyroid dysfunction if present
Suppressive therapy with levothyroxine is sometimes used for benign nodules, but its efficacy in preventing growth or malignancy in children is not well-established and is generally not recommended as a primary strategy.
Surgical Management:
Indicated for nodules classified as FN/SFN, suspicious for malignancy, or malignant by FNA
Definitive treatment involves thyroidectomy (lobectomy or total thyroidectomy) based on the extent of disease and histology
Central and/or lateral neck dissection may be performed for lymph node involvement
The goal is complete tumor removal while preserving parathyroid function and recurrent laryngeal nerve integrity.
Supportive Care:
Postoperative care includes monitoring for hypocalcemia, vocal cord function, and pain management
Long-term follow-up is essential, including periodic physical examinations, ultrasound, and thyroglobulin levels if indicated, to monitor for recurrence or metastatic disease.
Complications
Early Complications:
Intraoperative bleeding, recurrent laryngeal nerve injury (leading to vocal cord paralysis), hypoparathyroidism (transient or permanent), infection, hematoma formation.
Late Complications:
Thyroid hormone deficiency (hypothyroidism) requiring lifelong replacement therapy
Recurrence of disease
Metastasis to lymph nodes or distant sites
Surgical scar
Chronic hoarseness.
Prevention Strategies:
Meticulous surgical technique by experienced surgeons
Careful identification and preservation of the recurrent laryngeal nerves and parathyroid glands
Close follow-up for early detection of recurrence.
Prognosis
Factors Affecting Prognosis:
Histological subtype (papillary and follicular thyroid carcinoma have good prognosis)
Stage at diagnosis
Extrathyroidal extension
Presence of lymph node or distant metastases
Completeness of surgical resection
Response to adjuvant therapy (radioiodine, TSH suppression).
Outcomes:
Overall prognosis for differentiated thyroid cancer in children is generally good, with high cure rates and excellent long-term survival when managed appropriately
However, recurrence rates are higher than in adults, necessitating vigilant long-term follow-up.
Follow Up:
Regular clinical examinations, ultrasound of the neck, and serum TSH and thyroglobulin levels (if indicated) are crucial for detecting recurrence or persistent disease
Frequency and duration of follow-up are individualized based on risk stratification.
Key Points
Exam Focus:
High index of suspicion for malignancy in pediatric thyroid nodules
Key ultrasound features of malignancy (microcalcifications, hypoechogenicity, irregular margins, etc.)
Interpretation of FNA cytology categories (Bethesda system)
Indications for surgery
Postoperative management and follow-up protocols.
Clinical Pearls:
Always consider radiation history
Palpable nodule in a child warrants investigation
Don't dismiss benign FNA results without considering ultrasound context
Multidisciplinary team approach (pediatrician, endocrinologist, radiologist, surgeon, pathologist) is vital.
Common Mistakes:
Delaying FNA in children with palpable nodules
Over-reliance on benign FNA results without considering clinical and ultrasound findings
Inadequate surgical resection or insufficient lymph node management for malignant nodules
Inadequate long-term follow-up.