Thyroblastoma: A DICER1-associated embryonal neoplasm and fine needle aspiration diagnostic criteria

Diagnosis and treatment of thyroblastoma: a case report and review of literature

Background and objective

The diagnosis of thyroblastoma initially identified as a thyroid malignant teratoma was subsequently classified as a distinct entity by the World Health Organization (WHO) in 2022. This classification was based on the observation that the tumor presents with independent primitive multilineage elements and is frequently associated with DICER1 hotspot mutations.The objective of this study was to explore and investigate the clinicopathologic characteristics, molecular features and treatment strategies of patients with thyroblastoma, followed by a review of the previous relevant literature.

Methods

The clinical manifestations, pathological characteristics, molecular features and treatment strategies of the initial case of thyroblastoma pathologically confirmed in China were analyzed.

Results

The tumor was revealed to have high invasive potential, rapid disease progression, and primitive multilineage elements of pathology, including immature thyroid epithelium, spindled mesenchymal proliferations, and neuroepithelial blastema. Next-generation sequencing (NGS) confirmed the presence of germline DICER1 heterozygous pathogenic mutation at p.G1784* in patient, accompanied by the somatic hotspot mutation at p.E1813D of the RNase IIIb domain. Despite local thyroid tumor resection, the disease continued to progress rapidly. However, chemotherapy with BEP led to a reduction in the tumor. The patient's progression-free survival (PFS) reached 15 months following the administration of BEP chemotherapy in conjunction with local radiotherapy. The patient ultimately died of cardiac arrest resulting from the progression of the cancer thrombus to the right atrium and right ventricle.

Conclusion

Although thyroblastoma has been treated as a separate entity with its distinctive morphologic and molecular characteristics, its clinicopathological features, diagnosis and treatment methods and prognosis remain poorly understood, which requires more accumulated clinical case data to provide basis for the correct diagnosis and treatment in the future.

Pleuropulmonary blastoma and DICER1-related tumor predisposition: from clinicopathologic observations to clinical trial

PURPOSE OF REVIEW

Pleuropulmonary blastoma (PPB) is a rare primary lung neoplasm of infancy and childhood. The purpose of this review is to highlight recent developments in our understanding of PPB and research strategies to facilitate future rare cancer research.

RECENT FINDINGS

The International PPB/DICER1 Registry has recently assembled the largest-ever cohorts of type I and Ir PPB and type II and III PPB. These analyses were strengthened by robust histologic, genetic and longitudinal data made possible by systematic data collection and abstraction and dedicated central pathology review. These cohorts have laid the groundwork for a prospective consortium-based clinical trial to assess response to camptothecins in type II and III PPB and standardize the use of chemotherapy in type I PPB.

SUMMARY

Significant strides in the study of PPB have been made through clinical, laboratory and translational research, multidisciplinary collaborations and the generous contributions of patients, families and referring physicians. Ongoing advancements will continue to depend on multidisciplinary, multiperspective global collaborations.

DICER1-Related Tumor Predisposition: Identification of At-risk Individuals and Recommended Surveillance Strategies

PURPOSE

DICER1-related tumor predisposition increases risk for a spectrum of benign and malignant tumors. In 2018, the International Pleuropulmonary Blastoma (PPB)/DICER1 Registry published guidelines for testing- and imaging-based surveillance of individuals with a known or suspected germline DICER1 pathogenic or likely pathogenic (P/LP) variant. One of the goals of the Registry is to continue to refine these guidelines as additional data become available.

EXPERIMENTAL DESIGN

Individuals were enrolled in the International PPB/DICER1 Registry, the International Ovarian and Testicular Stromal Tumor Registry, and/or the NCI Natural History of DICER1 Syndrome study.

RESULTS

Review of participant records identified 713 participants with a germline DICER1 P/LP variant from 38 countries. To date, 5 cases of type I and 29 cases of type Ir PPB have been diagnosed by surveillance in enrolled individuals. One hundred and three individuals with a germline P/LP variant developed a primary ovarian Sertoli-Leydig cell tumor at a median age of 14 years (range: 11 months-66 years); 13% were diagnosed before 8 years of age, the current age of onset of pelvic surveillance. Additionally, 4% of Sertoli-Leydig cell tumors were diagnosed before 4 years of age.

CONCLUSIONS

Ongoing data collection highlights the role of lung surveillance in the early detection of PPB and suggests that imaging-based detection and early resection may decrease the risk of advanced PPB. DICER1-related ovarian tumors were detected before 8 years of age, prompting the Registry to recommend earlier initiation of ovarian surveillance with pelvic ultrasound beginning at the time of detection of a germline DICER1 P/LP variant.

Comprehensive evaluation of cytomorphologic, histologic, and molecular features of DICER1-altered thyroid lesions on FNA: A multipractice experience

BACKGROUND

DICER1 mutations, though infrequent, are encountered on preoperative molecular testing of indeterminate adult and pediatric thyroid fine-needle aspiration (FNA) specimens. Yet, published cytomorphologic features of DICER1-altered thyroid lesions are limited. Cytomorphological features of DICER1-altered thyroid lesions were examined in a multipractice FNA cohort with clinical, radiological, and histologic data.

METHODS

The cohort comprised 18 DICER1-altered thyroid FNAs, with 14 having slides available and eight having corresponding surgical resections. Smears, ThinPrep, and formalin-fixed cell block slides were reviewed and correlated with histology, when available. Clinical and radiologic data were obtained from the medical record.

RESULTS

Most DICER1-altered FNAs were classified as atypia of undetermined significance (94.4%). DICER1 mutations occurred in codons 1709 (50%), 1810 (27.8%), and 1813 (22.2%). One patient had an additional DICER1 p.D1822N variant in both of their FNAs. Lesions were often hypoechoic (35.3%) and solid (47.1%) on ultrasound. Notable cytomorphologic features include mixed but prominent microfollicular or crowded component, variable colloid, and insignificant nuclear atypia. On resection (n = 10), histologic diagnoses ranged from benign follicular adenoma and low-risk follicular thyroid carcinoma to high-grade follicular-derived nonanaplastic thyroid carcinoma. Subcapsular infarct-type change was the most common histologic change. There was no evidence of recurrence or metastasis in eight patients on limited follow-up.

CONCLUSION

DICER1-altered thyroid lesions occurred frequently in young females and FNAs show RAS-like cytomorphology including crowded, mixed macro-/microfollicular pattern, and bland nuclear features. On resection, DICER1-altered thyroid lesions include benign (50%), low-risk lesions (30%), or high-risk malignancies (20%).

Thyroid nodules with DICER1 mutation or PTEN alteration: A comparative cytologic, clinical, and molecular study of 117 FNA cases

BACKGROUND

DICER1 mutations and PTEN alterations are increasingly detected by thyroid fine-needle aspiration (FNA). Both are associated with nodular thyroid disease and cancer. The authors analyzed a large comparative thyroid FNA cohort with DICER1 mutation or PTEN alteration.

METHODS

A total of 117 thyroid FNAs with DICER1 or PTEN alterations were retrieved from the databases of two academic medical institutions. Demographic, clinical, and radiologic data were collected; FNA slides were analyzed for 29 cytomorphologic features.

RESULTS

Of 117 thyroid FNAs, 36 (30.8%) had DICER1 mutation and 81 (69.2%) showed PTEN alteration. The DICER1 cohort had 33 (91.7%) females and three (8.3%) males (mean, 40.9 years); 61.8% had multinodular disease. FNAs were classified as atypia of undetermined significance (AUS), 23 (63.9%); follicular neoplasm (FN), 12 (33.3%); and malignant, 1 (2.8%). The PTEN subgroup had 66 (81.5%) females and 15 (18.5%) males (mean, 55.2 years) with increased multinodular disease (93.8%, p = .0016). PTEN FNAs had greater cytologic diversity: non-diagnostic, 2 (2.5%); benign, 5 (6.2%); AUS, 44 (54.3%); FN, 24 (29.6%); and malignant, 6 (7.4%). Both DICER1 and PTEN cases showed a range of resected tumor subtypes. The DICER1 cohort included thyroblastoma, and the PTEN group included anaplastic carcinoma. The cytomorphology of DICER1 and PTEN cases showed overlapping features, especially microfollicular patterns. Minor cytomorphologic differences included papillary patterns in DICER1 (p = .039), and oncocytic changes (p < .0001) in PTEN.

CONCLUSIONS

DICER1 and PTEN FNAs reveal many cytologic similarities. DICER1 patients are younger, and PTEN patients had multinodular disease. Awareness of these genetic cohorts can identify patients at risk for thyroid cancer.

Expanding Our Knowledge of DICER1 Gene Alterations and Their Role in Thyroid Diseases

Mutations in DICER1, a gene involved in RNA interference, have been associated with a wide range of multi-organ neoplastic and non-neoplastic conditions. Historically known for its association with pleuropulmonary blastoma, DICER1 syndrome has received more attention due to the association with newly discovered diseases and tumors. Recent studies evaluating DICER1 mutations and DICER1-driven thyroid disease in both pediatric and adult thyroid nodules revealed thyroid disease as the most common manifestation of DICER1 mutations. This study undertakes a comprehensive investigation into DICER1 mutations, focusing on their role in thyroid diseases. Specific attention was given to thyroid follicular nodular disease and differentiated thyroid carcinomas in infancy as highly indicative of germline DICER1 mutation or DICER1 syndrome. Additionally, poorly differentiated thyroid carcinoma and thyroblastoma were identified as potential indicators of somatic DICER1 mutations. Recognizing these manifestations should prompt clinicians to expedite genetic evaluation for this neoplastic syndrome and classify these patients as high risk for additional multi-organ malignancies. This study comprehensively synthesizes the current knowledge surrounding this genetically associated entity, providing intricate details on histologic findings to facilitate its diagnosis.