Papillary thyroid carcinoma with nodular fasciitis-like stroma and β-catenin gene mutations: report of a recurrent case

Abstract

Papillary thyroid carcinoma with nodular fasciitis-like stroma (PTC-NFS) is a rare lesion with dual pathological features, that behaves more aggressively if positive for β-catenin gene (CTNNB1) mutations. Recently, we encountered a recurrent PTC-NFS with CTNNB1 mutations. A 48-year-old female presented with a recurrent enlarging tumor with a diagnosis of desmoid-type fibromatosis 6 months after her initial operation for PTC-NFS. Over a 2-year observation period, she underwent remedial surgery to resect the recurrent tumor. During the operation, the left recurrent laryngeal nerve was engulfed and scarified. Local invasion, β-catenin aberrant staining, and CTNNB1 mutations were detected both in the primary tumor stroma and the recurrent tumor. This case indicates that CTNNB1 mutation screening and β-catenin staining should be performed in PTC-NFS cases as a predictor for recurrence. If either of these are positive, a wider surgical resection should be adopted to achieve negative margins. Otherwise, radiotherapy should be considered. Furthermore, the lesion might be better known as papillary thyroid carcinoma with desmoid-type fibromatosis in such situations to reflect its local aggressive nature.

Keywords: CTNNB1 mutations; Papillary thyroid carcinoma; desmoid tumor; desmoid-type fibromatosis; β-catenin aberrant staining.

Figure 1

A. Ultrasound image of the primary tumor showing an irregular hypo-echo mass (3.46 × 2.04 cm) in the left thyroid lobe. B. Ultrasound image of the recurrent tumor (white arrow) 6 months after the initial operation. An irregular hypo-echo mass (1.2 × 0.67 cm) with ill-defined margins is shown. C. Computed tomography (CT) image of the recurrent tumor (black arrow) 1 month before the second operation. The tumor is superior to the hyoid bone¹, and inferior to the innominate vein². D. CT cross section of the recurrent tumor showing the shift in muscles and cervical vessels.

Figure 2

A. Overview of the primary tumor. The mesenchymal component (black arrow) surrounds and separates the epithelial component (white arrow) into small nodules (hematoxylin & eosin (HE) staining; magnification, 40×). B. The epithelial component of the primary tumor. Epithelial cells are arranged in a papillary architecture and show irregular, overlapping nuclei with disturbed polarity (HE staining; magnification, 400×). C. Overview of the recurrent tumor. Homogeneous fibrous cells with varying amounts of collagen (HE staining; magnification, 20×). Insert shows fibrous cells arranged in bundles or fascicles, with varying amounts of collagen (HE staining; magnification, 400×). D. β-catenin staining of the recurrent tumor. Aberrantly-stained nuclei and cytoplasmic staining of fibrous cells (magnification, 400×). E. Cut section of the recurrent tumor. Homogeneous, yellowish cut section (7.5 × 3.5 cm). F. CTNNB1 mutation analysis of the recurrent tumor: c.133C>T (p. S45F) mutation was detected in exon 2 of CTNNB1.