A unique case of two somatic APC mutations in an early onset cribriform-morular variant of papillary thyroid carcinoma and overview of the literature

Cribriform-morular Thyroid Carcinoma Arising in a Medulloblastoma Survivor: Two Metachronous Tumors Shared with the Activation of the Wnt Signaling Pathway

Wnt signaling pathway activation is involved in the pathogenesis of a series of malignant tumors and is characterized by the nuclear accumulation of β-catenin protein. The occurrence of two or more Wnt pathway-associated tumors in a single individual is uncommon and generally attributed to inherited cancer syndrome, especially familial adenomatous polyposis (FAP). Herein, we presented a rare case of a child who suffered from the occurrence of Wnt-activated medulloblastoma and cribriform-morular thyroid carcinoma (CMTC) within a 9-year interval. She had no history of FAP and harbored an unexpected somatic mutation of the APC gene in the CMTC tumor. The potential agents involved in the pathogenesis of the two molecular-linked tumors other than FAP were discussed in this report.

Cribriform Morular Thyroid Carcinoma: A Rare Case and Associated Uncommon Features

Cribriform morular thyroid carcinoma has been added under tumors of uncertain histogenesis. Its peculiar clinical, histomorphological pattern, and immunohistochemical profile have been proved different from papillary thyroid carcinoma. A 59-year-old female patient had a lesion in the left lobe of the thyroid. Fine needle aspiration cytology was reported as medullary thyroid carcinoma. The total thyroidectomy specimen showed a predominantly solid tumor of size 9.5 cm in the left lobe. Microscopy showed a mixed growth pattern with the dominant cribriform and solid morular area. Nuclear features of papillary carcinoma were not seen. Squamoid morules had nuclear clearing. Marked stromal hyalinization and calcification were noted. Extrathyroidal extension, lymphovascular invasion, and lymph node metastasis were not identified. Immunohistochemically the tumor cells were diffuse and strong nuclear positive for β-catenin, TTF1, PAX8, estrogen receptor, focal, and weak positivity for CD5. Synaptophysin, calcitonin, thyroglobulin, and CDX2 were negative. We report this rare cribriform morular thyroid carcinoma case with its associated uncommon histological and immunohistochemical features.

The First Case of Cribriform-Morular Thyroid Carcinoma and FAP with APC Gene Mutation in China: A Case Report and Brief Review

The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is now designated as morular cribriform thyroid carcinoma (CMTC) according to the 5^th edition of the World Health Organization (WHO) Classification of Thyroid Tumors. CMTC can appear within a familial adenomatous polyposis (FAP) or be sporadic. We report the first case of a young female patient in China who was diagnosed with FAP and CMTC with a mutation in exon 16 of the APC gene underlying the disease. The main purpose of this case report is to provide a special pathological type of thyroid tumors, which is expected to be helpful for clinical work in the future.

De novo familial adenomatous polyposis associated thyroid cancer with a c.2929delG frameshift deletion mutation in APC: a case report and literature review

BACKGROUND

Germline mutations in the APC gene located on chromosome 5q 21-22 can lead to familial adenomatous polyposis (FAP) and the development of colorectal cancer (CRC) if left untreated. As a rare extracolonic manifestation, thyroid cancer is diagnosed in about 2.6% of FAP patients. The genotype-phenotype correlation in FAP patients with thyroid cancer remains unclear.

CASE PRESENTATION

We present a 20-year-old female of FAP with thyroid cancer as the initial manifestation. The patient was asymptomatic and developed colon cancer liver metastases 2 years after the diagnosis of thyroid cancer. The patient underwent multiple surgical treatments in several organs, and regular colonoscopy with endoscopic polypectomy was performed. Genetic testing demonstrated the c.2929delG (p.Gly977Valfs*3) variant in exon 15 of the APC gene. This represents a previously undescribed APC mutation. This mutation causes loss of multiple structures on the APC gene including the 20-amino acid repeats, the EB1 binding domain, and the HDLG binding site, which may be pathogenic through β-catenin accumulation, cell cycle microtubule dysregulation, and tumor suppressor inactivation.

CONCLUSIONS

We report a de novo FAP case with thyroid cancer presenting atypically aggressive features harboring a novel APC mutation and review APC germline mutations in patients with FAP-associated thyroid cancer.

Selected Topics in the Pathology of the Thyroid and Parathyroid Glands in Children and Adolescents

The goals of this chapter in keeping with the overall general themes of this special edition will be (1) to highlight aspects of development of the thyroid and parathyroid glands with particular focus on the role and contribution of the neural crest (or not) and how this may impact on the pathology that is seen, (2) to emphasize those lesions particularly more commonly arising in the pediatric population that actually generate specimens that the surgical pathologist would encounter, and (3) highlight more in depth specific lesions associated with heritable syndromes or specific gene mutations since the heritable syndromes tends to manifest in the pediatric age group. In this light, the other interesting areas of pediatric thyroid disease including medical thyroid diseases, congenital hypothyroidism, anatomic variants and aberrations of development that lead to structural anomalies will not be emphasized here.

Inherited Follicular Epithelial-Derived Thyroid Carcinomas: From Molecular Biology to Histological Correlates

Cancer derived from thyroid follicular epithelial cells is common; it represents the most common endocrine malignancy. The molecular features of sporadic tumors have been clarified in the past decade. However the incidence of familial disease has not been emphasized and is often overlooked in routine practice. A careful clinical documentation of family history or familial syndromes that can be associated with thyroid disease can help identify germline susceptibility-driven thyroid neoplasia. In this review, we summarize a large body of information about both syndromic and non-syndromic familial thyroid carcinomas. A significant number of patients with inherited non-medullary thyroid carcinomas manifest disease that appears to be sporadic disease even in some syndromic cases. The cytomorphology of the tumor(s), molecular immunohistochemistry, the findings in the non-tumorous thyroid parenchyma and other associated lesions may provide insight into the underlying syndromic disorder. However, the increasing evidence of familial predisposition to non-syndromic thyroid cancers is raising questions about the importance of genetics and epigenetics. What appears to be "sporadic" is becoming less often truly so and more often an opportunity to identify and understand novel genetic variants that underlie tumorigenesis. Pathologists must be aware of the unusual morphologic features that should prompt germline screening. Therefore, recognition of harbingers of specific germline susceptibility syndromes can assist in providing information to facilitate early detection to prevent aggressive disease.