Cribriform morular thyroid carcinoma: a case report with pathological, immunohistochemical, and molecular findings suggesting an origin from follicular cells (or their endodermal precursors).

Cribriform morular thyroid carcinoma (CMTC) is a rare malignant thyroid tumor with a peculiar growth pattern secondary to permanent activation of the WNT/ß-catenin pathway. CMTC may be associated with familial adenomatous polyposis or sporadic; it shares morphological features with papillary thyroid carcinoma (PTC) and was considered a variant of PTC in the 2017 WHO classification of tumors of endocrine organs. The new 5th edition of the WHO classification of endocrine and neuroendocrine tumors considered CMTC an independent thyroid neoplasm of uncertain histogenesis. A thymic/ultimobranchial pouch-related differentiation in CMTC has been recently postulated. We, however, have used the pathological and immunohistochemical features of this case of CMTC with 2 novel oncogenic somatic variants (c.3428_3429insA, p.(Tyr1143Ter) and c.3565del, p. (Ser1189Hisfs*76) of the APC gene to propose an origin from follicular cells (or their endodermal precursors). As usual in CMTC, the morular component of this tumor was positive for CDX2. Given the fact that WNT/ß-catenin signaling, through CDX2, activates large intestine and small intestine gene expression, we postulate that in CMTC, the tumor cells have their terminal differentiation blocked, thus showing a peculiar primitive endodermal (intestinal-like) phenotype negative for sodium-iodide symporter, thyroperoxidase, and thyroglobulin. Establishing the histogenesis of CMTC is very relevant for the development of appropriate therapies of redifferentiation, particularly in patients where the tumor cannot be controlled by surgery.

Clinical characteristics and prognosis of familial nonmedullary thyroid carcinoma.

INTRODUCTION: Familial non-medullary thyroid carcinoma (FNMTC) is defined by the presence of 2 or more first-degree family members with differentiated thyroid carcinoma (DTC). The aim of this study is to compare clinicopathological features and prognosis of FNMTC and sporadic carcinoma (SC). MATERIALS AND METHODS: Retrospective study of DTC included in the hospital database during the period 1990-2018. RESULTS: A total of 927 patients were analyzed, 61 of them were FNMTC, with a mean follow-up of 9.7 ±â€¯6.5 years. The prevalence of FNMTC was 6.6%, with a lower TNM staging presentation (P = 0.003) consequence of a higher proportion of tumors smaller than 2 cm (P = 0.003), combined with a greater multifocality (P = 0.034) and papillary histologic subtype (P = 0.022) compared to SC. No significant differences in age at diagnosis (P = 0.347), gender (P = 0.406), neither in other aggressiveness markers (bilaterality, extrathyroidal extension, lymph node involvement and metástasis) were detected. Rate of persistence/recurrence (P = 0.656), disease-free survival (P = 0.929) and mortality caused by the tumor itself (P = 0.666) were comparable. Families with ≥3 affected relatives, had smaller tumors (P = 0.005), more multifocality (P = 0.040) and bilaterality (P = 0.002), as well as a higher proportion of males (P = 0.020). Second generation patients present earlier FNMTC compared to those of the first generation (P = 0.001). CONCLUSION: In our study FNMTC presents a lower TNM staging, higher multifocality and papillary variant, with similar aggressiveness and prognosis compared to SC.

Clinical characteristics and prognosis of familial nonmedullary thyroid carcinoma. / Características clínicas y pronósticas del carcinoma familiar de tiroides no medular.

INTRODUCTION: Familial non-medullary thyroid carcinoma (FNMTC) is defined by the presence of 2or more first-degree family members with differentiated thyroid carcinoma (DTC). The aim of this study is to compare clinicopathological features and prognosis of FNMTC and sporadic carcinoma (SC). MATERIALS AND METHODS: Retrospective study of DTC included in the hospital database during the period 1990-2018. RESULTS: A total of 927 patients were analyzed, 61 of them were FNMTC, with a mean follow-up of 9.7±6.5 years. The prevalence of FNMTC was 6.6%, with a lower TNM staging presentation (P=.003) consequence of a higher proportion of tumors smaller than 2 centimeters (P=.003), combined with a greater multifocality (P=.034) and papillary histologic subtype (P=.022) compared to SC. No significant differences in age at diagnosis (P=.347), gender (P=.406), neither in other aggressiveness markers (bilaterality, extrathyroidal extension, lymph node involvement and metástasis) were detected. Rate of persistence/recurrence (P=.656), disease-free survival (P=.929) and mortality caused by the tumor itself (P=.666) were comparable. Families with ≥3 affected relatives, had smaller tumors (P=.005), more multifocality (P=.040) and bilaterality (P=.002), as well as a higher proportion of males (P=.020). Second generation patients present earlier FNMTC compared to those of the first generation (P=.001). CONCLUSION: In our study FNMTC presents a lower TNM staging, higher multifocality and papillary variant, with similar aggressiveness and prognosis compared to SC.

¿Está indicado el examen sistemático de la función tiroidea durante el embarazo? Réplica del autor / Is thyroid function screening warranted during pregnancy? Author´s reply

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