Clinicopathological and molecular mechanisms of cribriform morular thyroid carcinoma: a case report and a literature review

Abstract

Introduction and importance: Cribriform morular thyroid carcinoma (CMTC) is a rare malignant thyroid carcinoma, mainly seen in young Asian women. CMTC is related to the activation of the WNT/β-catenin signaling pathway, so CMTC is usually closely related to familial adenomatous polyposis (FAP).

Case presentation: The patient was a 13-year-and-11-month-old girl with a right neck mass. After total thyroidectomy and bilateral lymph node dissection, the tumor's pathological report is CMTC, and 31 lymph nodes exhibited metastatic carcinoma. Adenomatous polyposis coli (APC) gene mutation has been detected.

Clinical discussion: CMTC has typical cribriform and morular structures under microscope. It is associated with the WNT/β-catenin signaling pathway through inactivating mutations in the APC, CTNNB1, and AXIN1 genes, thereby enabling WNT gene expression and participating in proliferation, invasion, dedifferentiation, and tumorigenesis.

Conclusion: CMTC is usually closely related to FAP. It requires clinical attention, and the patient's intestinal condition still needs to be closely monitored after surgery.

Keywords: APC mutations; WNT/β-catenin signaling pathway; cribriform morular thyroid carcinoma; familial adenomatous polyposis; thyroid carcinoma.

Figure 1.

Preoperative neck ultrasonography of the patient revealed that the right thyroid gland was nearly entirely occupied by the tumor, exhibiting a hypoechoic pattern with tiny punctate calcifications. Based on the ultrasonographic findings, there is a high suspicion of malignancy for this tumor.

Figure 2.

Pathological specimen of the right thyroid lobe, displaying a grayish-white cut surface. The tumor is solid and firm in consistency. The black-stained regions are attributed to the injection of a carbon nanoparticle tracer into the thyroid prior to surgical resection.

Figure 3.

A: HE staining demonstrates morula bodies (wide arrow) and some cribriform architectures (narrow arrow; magnification ×50); B: HE staining demonstrates morula bodies (wide arrow; magnification ×50); C: HE staining demonstrates morula bodies (wide arrow) and some cribriform architectures (narrow arrow; magnification ×100); D: Immunohistochemical staining indicates negativity for the BRAF V600E mutation (magnification ×50); E: Immunohistochemical staining reveals strong positivity for TTF-1 (magnification ×100); F: Immunohistochemical staining shows negativity for VIM (magnification ×100).