Characteristics of Follicular Variant Papillary Thyroid Carcinoma in a Pediatric Cohort

Thyroid Nodules and Follicular Cell-Derived Thyroid Carcinomas in Children

Although pediatric thyroid tumors have many similarities to those occurring in adults, significant differences are also recognized. For example, although thyroid nodules in children are much less common than in adults, a higher percentage is malignant. Moreover, while pediatric papillary thyroid carcinoma (PTC) is associated with more advanced disease, death due to disease in children and adolescents is very rare, even when distant metastases are present. Some subtypes of thyroid carcinoma, like diffuse sclerosing variant, are especially common in children and adolescents. Moreover, certain histologic findings, such as a tall cell morphology or increased mitotic activity, may not carry the same prognostic significance in children as in adults. Recent studies exploring the molecular underpinnings of pediatric thyroid carcinoma indicate that while driver alterations of thyroid tumorigenesis in children and adults are essentially the same, they occur at very different frequencies, with translocation-associated tumors (most commonly harboring RET and NTRK fusions) comprising a sizable and distinct group of pediatric PTC. DICER1 mutations, an infrequent mutation in adult thyroid tumors, are relatively frequent in pediatric encapsulated follicular-patterned thyroid tumors (with or without invasion or nuclear features of PTC). Additionally, tumor predisposition syndromes (most notably DICER1 syndrome and PTEN hamartoma tumor syndromes such as Cowden syndrome) should be considered in children with thyroid tumors, especially follicular-patterned thyroid tumors and poorly differentiated thyroid carcinoma. This review will explore the current state of knowledge of thyroid nodules and carcinomas in children and adolescents.

Clinicopathologic Characteristics of Pediatric Follicular Variant of Papillary Thyroid Carcinoma Subtypes: A Retrospective Cohort Study

Introduction: Follicular patterned thyroid nodules with nuclear features of papillary thyroid carcinoma (PTC) encompass a range of diagnostic categories with varying risks of metastatic behavior. Subtypes include the invasive encapsulated follicular variant of PTC (Ienc-fvPTC) and infiltrative fvPTC (inf-fvPTC), with tumors lacking invasive features classified as noninvasive follicular thyroid neoplasms with papillary-like features (NIFTPs). This study aimed to report the clinical and histological features of pediatric cases meeting criteria for these histological subtypes, with specific focus on Ienc-fvPTC and inf-fvPTC. Methods: In this retrospective cohort study, pediatric patients with thyroid neoplasms showing follicular patterned growth and nuclear features of PTC noted on surgical pathology between January 2010 and January 2021 were retrospectively reviewed and classified according to the recent 2022 World Health Organization (WHO) criteria. Clinical and histopathologic parameters were described for NIFTP, Ienc-fvPTC, and inf-fvPTC subtypes, with specific comparison of Ienc-fvPTC and inf-fvPTC cases. Results: The case cohort included 42 pediatric patients, with 6 (14%), 25 (60%), and 11 (26%) patients meeting criteria for NIFTP, Ienc-fvPTC, and inf-fvPTC, respectively. All cases were rereviewed, and 5 patients originally diagnosed with Ienc-fvPTC before 2017 were reappraised as having NIFTPs. The NIFTP cases were encapsulated tumors without invasive features, lymph node or distant metastasis, or disease recurrence. Ienc-fvPTC tumors demonstrated clearly demarcated tumor capsules and capsular/vascular invasion, while inf-fvPTC tumors displayed infiltrative growth lacking a capsule. inf-fvPTC cases had increased prevalence of malignant preoperative cytology, lymph node metastasis, and distant metastasis (p < 0.01). These cases were treated with total thyroidectomy, lymph node dissection, and subsequent radioactive iodine therapy. Preliminary genetic findings suggest a predominance of fusions in inf-fvPTC cases versus point mutations in Ienc-fvPTC (p = 0.02). Conclusions: Pediatric NIFTP and fvPTC subtypes appear to demonstrate alignment between clinical and histological risk stratification, with indolent behavior in Ienc-fvPTC and invasive features in inf-fvPTC tumors.

Paediatric differentiated thyroid carcinoma: a UK National Clinical Practice Consensus Guideline

This guideline is written as a reference document for clinicians presented with the challenge of managing paediatric patients with differentiated thyroid carcinoma up to the age of 19 years. Care of paediatric patients with differentiated thyroid carcinoma differs in key aspects from that of adults, and there have been several recent developments in the care pathways for this condition; this guideline has sought to identify and attend to these areas. It addresses the presentation, clinical assessment, diagnosis, management (both surgical and medical), genetic counselling, follow-up and prognosis of affected patients. The guideline development group formed of a multi-disciplinary panel of sub-speciality experts carried out a systematic primary literature review and Delphi Consensus exercise. The guideline was developed in accordance with The Appraisal of Guidelines Research and Evaluation Instrument II criteria, with input from stakeholders including charities and patient groups. Based on scientific evidence and expert opinion, 58 recommendations have been collected to produce a clear, pragmatic set of management guidelines. It is intended as an evidence base for future optimal management and to improve the quality of clinical care of paediatric patients with differentiated thyroid carcinoma.

Clinical Course of Early Postoperative Hypothyroidism Following Thyroid Lobectomy in Pediatrics

Introduction: Thyroid lobectomy reduces risks of surgical complications and need for levothyroxine (LT4). We aimed at identifying the clinical course and risk factors for postlobectomy hypothyroidism to optimize surgical counseling and management in pediatric patients undergoing lobectomy. Methods: Clinical and biochemical presentations pre- and postlobectomy were retrospectively reviewed for 110 patients who underwent thyroid lobectomy between 2008 and 2020 at the Children's Hospital of Philadelphia. Results: Approximately 28.2% of patients (31/110) developed postlobectomy hypothyroidism defined by an elevated thyrotropin (TSH) level, including 24.5% (27/110) with subclinical hypothyroidism (TSH >4.5 and <10.0 mIU/L) and 3.6% (4/110) with overt hypothyroidism (TSH >10.0 mIU/L). LT4 was initiated in 12.7% (14/110) of cases. Most patients (81.6%; 84/103) recovered euthyroidism within 12 months postlobectomy. When excluding patients with autonomous nodule(s), median preoperative TSH was 1.09 (interquartile range [IQR] = 0.70-1.77) mIU/L and 1.80 (IQR = 1.02-2.68) mIU/L in euthyroid and hypothyroid patients, respectively, with multivariate logistic regression confirming the association between an increased preoperative TSH and postlobectomy hypothyroidism (odds ratio = 1.8 [confidence interval 1.08-3.13], p = 0.024). Of the patients who underwent thyroid lobectomy and developed postoperative hypothyroidism (n = 31), 38.7% (12/31) had a preoperative diagnosis of an autonomously functioning thyroid nodule. Conclusions: Thyroid function should be evaluated postlobectomy to assess the need for LT4. LT4 should be considered if the TSH remains elevated, especially if an upward trend is observed or TSH is >10.0 mIU/L. Suppressed preoperative TSH associated with autonomous nodules is an independent risk factor for postlobectomy hypothyroidism.

Fine Needle Aspiration Cytology Implementation and Malignancy Rates in Children and Adolescents Based on Japanese Guidelines: The Fukushima Health Management Survey

Background: The thyroid ultrasound examination (TUE) program was initiated among the residents of Fukushima Prefecture aged ≤18 years at the time of the Fukushima Dai-ichi Nuclear Power Plant accident. In this program, fine needle aspiration cytology (FNAC) was performed only in cases that conformed to the Japanese guidelines for the management of thyroid nodules. To analyze the suitability of the protocol in the TUE, we analyzed the implementation rate of FNAC and the detection rate of thyroid malignancy. Methods: There were 299,939 and 269,659 voluntary participants in the Preliminarily Baseline Survey (PLBS), first-round survey, and the first Full-scale Survey (FSS), second-round survey, of the TUE, respectively. FNAC is recommended for nodules with diameters 5.1-10.0 mm showing sonographic characteristics that are strongly suspicious for thyroid carcinoma; diameters 10.1-20.0 mm with characteristics that are suspicious for carcinoma; and all nodules with diameters >20 mm. Results: In the PLBS and the first FSS, 1362 and 1382 cases with thyroid nodules sized ≥5.1 mm in diameter were found, respectively. The implementation rates of FNAC in the PLBS were 20.1%, 63.2%, and 87.7% of subjects with nodules sized 5.1-10.0, 10.1-20.0, and ≥20.1 mm in diameter, respectively. In the first FSS, the FNAC implementation rates were 7.3%, 26.0%, and 50.0% in the subjects with nodules with diameters 5.1-10.0, 10.1-20.0, and ≥20.1 mm, respectively. In the subjects who underwent FNAC, the detection rates of malignant and suspected malignant nodules were 21.4% and 34.1% in the PLBS and first FSS, respectively. In the first FSS, malignant or suspected malignant nodules were found in 0.63% and 0.40% of subjects who had nodules of diameters ≤5.0 mm and 5.1-10.0 mm in the PLBS, respectively. In contrast, in the subjects with nodules measuring ≥10.0 mm in diameter in the PLBS, no malignancies were detected. Conclusions: The use of a protocol that conformed to the Japanese guidelines led to a reduction in the FNAC implementation rate and an increase in the malignancy detection rate in smaller nodules. In addition, the use of this strategy enabled us to avoid detection failure of thyroid carcinomas >10.0 mm.

Thyroid Lobectomy for T1 Papillary Thyroid Carcinoma in Pediatric Patients

Importance

The current recommendation for pediatric patients with papillary thyroid cancer (PTC) is a total thyroidectomy. This recommendation applies to all stages of PTC, including papillary thyroid microcarcinoma (≤1 cm, T1a) tumors.

Objective

To evaluate the characteristics of American Joint Committee on Cancer T1 PTC tumors in a large pediatric population and to identify a subgroup of patients who may benefit from a thyroid lobectomy instead of a total thyroidectomy.

Design, Setting, and Participants

This retrospective cohort study was conducted from January 1, 2009, to May 31, 2020. The study took place at a tertiary care medical center and included 102 patients who were surgically treated for T1 PTC: 52 with stage T1a (≤1 cm) tumors and 50 with stage T1b (>1 cm but ≤2 cm) tumors.

Main Outcomes and Measures

Primary outcomes included the presence of bilateral disease and lymph node metastasis.

Results

A total of 102 patients (mean age, 15.3 years [range, 9.7-18.9 years]; 84 girls [82.4%]) were included in the analysis. Among 52 patients with T1a tumors, 10 (19.2%) had bilateral disease, and 15 (28.8%) had central neck lymph node (N1a) metastasis. Among 50 patients with T1b tumors, 10 (20%) had bilateral and 13 (26%) had N1a disease. Of those with T1a, unilateral multifocality was associated with bilateral disease (odds ratio [OR], 2.1; 95% CI, 1.3-3.4) and N1a disease (OR, 5.1; 95% CI, 1.5-17.6). Both N1a disease (OR, 20.0; 95% CI, 3.5-115.0) and ≥4 positive lymph nodes (OR, 8.6; 95% CI, 1.2-60.9) were associated with bilateral disease. In patients with no pathologic evidence of lymph node metastasis (N0), there was a 95% rate of unilateral PTC. In patients with T1b tumors, unilateral multifocality was also associated with bilateral disease (OR, 1.8; 95% CI, 1.3-2.7). Patients with T1b tumors had an increased risk of lateral (N1b) neck lymph node metastasis when compared with those with T1a tumors (OR, 3.7; 95% CI, 1.0-14.5).

Conclusions and Relevance

The findings of this cohort study suggest that, in patients with unifocal T1a PTC without clinically evident nodal disease on preoperative ultrasonography, a thyroid lobectomy and central neck dissection may be considered. If there is no evidence of unilateral multifocality or if there are fewer than 4 positive lymph nodes on postoperative pathology, then close observation may be considered. These findings have substantial clinical implications and may result in practice changes regarding the extent of thyroid surgery on low-stage pediatric PTC.

Oncogene-specific inhibition in the treatment of advanced pediatric thyroid cancer

Papillary thyroid cancer (PTC) is the most common form of differentiated thyroid cancer in the pediatric population and represents the second most common malignancy in adolescent females. Historically, PTC has been classified on the basis of histology, however, accumulating data indicate that molecular subtyping based on somatic oncogenic alterations along with gene expression profiling can better predict clinical behavior and may provide opportunities to incorporate oncogene-specific inhibitory therapy to improve the response to radioactive iodine (RAI). In this issue of the JCI, Y.A. Lee, H. Lee, and colleagues showed that oncogenic fusions were more commonly associated with invasive disease, increased expression of MAPK signaling pathway genes (ERK score), and decreased expression of the sodium-iodine symporter, which was restored by RET- and NTRK-inhibitory therapy. These findings lend credence to the idea of reclassifying pediatric thyroid cancers using a three-tiered system, rather than the two-tiered adult system, and open avenues for the treatment of progressive, RAI-refractory PTC in patients.

Molecular Alterations in Relation to Histopathological Characteristics in a Large Series of Pediatric Papillary Thyroid Carcinoma from a Single Institution

Papillary thyroid carcinoma (PTC) presents distinct clinico-pathological and molecular differences in children compared with adult patients. Whether the presence of rearrangements or point mutations is associated with aggressive PTC clinical presentation is still controversial. In this study, PTCs diagnosed in patients aged less than 18 years were retrospectively searched from the institutional archive and tumor tissue was tested for point mutations in BRAF and RAS genes and for rearrangements in RET, NTRK1, NTRK3, ALK, PPARG, BRAF and THADA. A total of 163 PTCs were analyzed. Point mutations were found in 83 (51%) and gene fusions in 48 cases (30%). The most frequent alteration was the BRAFV600E mutation (36.8%), followed by NTRK3 fusion (11%), NRAS mutation (10.4%) and RET fusion (10.4%). Fusion-driven PTCs showed more frequently infiltrative growth, larger tumors, extrathyroidal extension and N1b disease. PTCs showing solid growth pattern were significantly enriched in gene fusions. This is one of the largest cohorts of pediatric PTCs. Fusion-driven tumors most frequently show aggressive pathological features; the search for rearrangements, especially in tumors with solid areas, could improve the characterization of pediatric PTCs and offer possible therapeutic options.

Pediatric Thyroid Cancer: Genetics, Therapeutics and Outcome

An increasing number of children are diagnosed with thyroid cancer. Most patients do not have an identifiable cause; however, tumor predisposition syndromes may be associated with development of both differentiated and medullary thyroid cancer. With an excellent prognosis for most patients, the goal of therapy is to optimize outcome and reduce complications. The increased knowledge of the oncogenic drivers provides opportunities to improve the accuracy of diagnosis, stratify surgery, and select systemic therapy that may be considered for neoadjuvant and adjuvant treatment. Treatment complications can be reduced by referral to regional, high-volume pediatric thyroid centers.

Case Report: Multifocal non-invasive follicular thyroid neoplasm with papillary-like nuclear features presenting in a female child

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was introduced as a separate entity by the World Health Organization in 2017 with strict inclusion and exclusion criteria.  Most NIFTP cases have been reported in adults and few cases have been diagnosed in children. Here, we present a classic case of NIFTP affecting a 10-year old female child. We also review previous reports of NIFTP in children regarding size, focality, nodal metastasis, recurrence, type of operation and follow-up data. The present report adds a new case of NIFTP in the paediatric age group characterized by multifocality, absence of nodal invasion and indolent course until last follow-up, recommending less aggressive management.

Bilateral papillary thyroid cancer in children: Risk factors and frequency of postoperative diagnosis

BACKGROUND

The recommendation for children with papillary thyroid cancer (PTC) is total thyroidectomy (TT) based on the incidence of bilateral disease. Evaluating this assumption, we reviewed the characteristics of bilateral PTC in a large cohort of children.

METHODS

A retrospective chart review for patients surgically treated for PTC from 2009 to 2018 analyzing preoperative risk factors, ultrasound findings, and pathology results was performed. Bilateral disease was defined as pathologic PTC in the contralateral lobe, including microscopic disease.

RESULTS

Of the 172 patients included, 38.4% had bilateral disease with 23% diagnosed postoperatively. Multifocal disease on ultrasound was associated with bilateral disease (OR 2.9, 95% CI 1.5-5.9, p = 0.002). Nodule dimension >2 cm was associated with increased risk for postoperative bilateral disease (OR 3.5, 95% CI 1.6-7.4, p = 0.001). Patients with bilateral disease were more likely to have extrathyroidal extension, lymphovascular invasion, positive central lymph nodes, and extranodal extension (p < 0.001 for all). Diffuse-sclerosing variant PTC was also associated with bilateral disease.

CONCLUSION

Thirty-eight percent of children were diagnosed with PTC demonstrate bilateral disease. Nearly one in four have occult bilateral disease. The features that predicted bilateral disease were multifocality, widely invasive PTC on ultrasound, and the presence of lymphadenopathy. Thus, TT is the appropriate surgical approach for pediatric patients with PTC.

TYPE OF STUDY

Clinical Research, Retrospective Review.

LEVEL OF EVIDENCE

Level IV.

Papillary and Follicular Thyroid Cancer in children and adolescents: Current approach and future directions

An increasing number of children are diagnosed with differentiated thyroid cancer. With an excellent prognosis for the majority of pediatric patients, the goal of therapy is to optimize outcome while reducing complications. Increased knowledge of the somatic, oncogenic driver mutations provides opportunities to improve the accuracy of diagnosis, to stratify surgery, and to treat patients with morbidly invasive or refractory disease. Treatment complications can be reduced by referral to regional, high-volume pediatric thyroid centers.

Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features in Children: An Institutional Experience and Literature Review

BACKGROUND

Papillary thyroid carcinoma (PTC) in children has a distinctive set of clinicopathologic features and molecular signature compared to their adult counterparts. The recent recommendation to reclassify encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) without invasion as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is based on evidence derived almost exclusively from studies in adults. Clinicopathologic studies restricted to pediatric NIFTP are limited.

METHODS

We retrospectively analyzed all pediatric PTC and NIFTP diagnosed and treated in our institution from 1999 to 2016 (n = 31).

RESULTS

Using recently published consensus diagnostic criteria, we identified 3 NIFTP and 2 infiltrative follicular variants of papillary thyroid carcinoma (FVPTC) among 31 cases. Two of the NIFTP cases were initially diagnosed as EFVPTC. All 3 patients with NIFTP had unifocal tumors of lower American Joint Committee on Cancer (AJCC) classification (T2 or lower) and were free of lymph node or distant metastasis. Total (n = 1) or completion (n = 2) thyroidectomy was performed in all cases, and only 1 NIFTP patient received subsequent radioablative therapy. No residual or recurrent disease has been observed during follow-up (15-138 months) in patients with NIFTP.

CONCLUSIONS

Our experience with NIFTP in children is similar to outcomes reported in adult studies, suggesting that pediatric NIFTP behave indolently as evidenced by the absence of local recurrence in our cohort.