Clinicopathological and molecular histochemical review of skull base metastasis from differentiated thyroid carcinoma

Abstract

Skull base metastasis from differentiated thyroid carcinoma including follicular thyroid carcinoma (FTC) and papillary thyroid carcinoma (PTC) is a rare clinical entity. Eighteen FTC cases and 10 PTC cases showing skull base metastasis have been reported. The most common symptom of skull base metastasis from FTC and PTC is cranial nerve dysfunction. Bone destruction and local invasion to the surrounding soft tissues are common on radiological imaging. Skull base metastases can be the initial clinical presentation of FTC and PTC in the presence of silent primary sites. The possibility of skull base metastasis from FTC and PTC should be considered in patients with the clinical symptoms of cranial nerve dysfunction and radiological findings of bone destruction. A variety of genetic alterations in thyroid tumors have been identified to have a fundamental role in their tumorigenesis. Molecular histochemical studies are useful for elucidating the histopathological features of thyroid carcinoma. Recent molecular findings may provide novel molecular-based treatment strategies for thyroid carcinoma.

Keywords: follicular thyroid carcinoma; iodine-131 brachytherapy; papillary thyroid carcinoma; skull base metastasis; thyroid-stimulating hormone suppression.

Fig. 1

a: CT scan reveals skull base tumor invading the right middle cranial fossa. b: Pathological examination confirms the tumor is FTC (Hematoxylin-eosin staining). c: BRAF-K601E mutation is observed in the tumor cell (arrow).

Fig. 2

a: CT scan reveals skull base tumor invading the left pyramidal bone. b: Pathological examination confirms the tumor is FTC (Hematoxylin-eosin staining). c: BRAF-G468E mutation is observed in the tumor cell (arrow).