Papillary thyroid carcinoma with fibromatosis-like stroma: a case report and review of the literature

Abstract

Background: Papillary thyroid carcinoma (PTC) is a common neoplasia with multiple variants. One of these extremely rare and poorly described variants is PTC with fibromatosis-like stroma (PTC-FMS), a peculiar entity distinguished by its predominant mesenchymal component. This paper reviews the literature, discusses the diagnostic challenges, and the clinical and surgical implications of this type of tumor which has fewer than 30 cases reported in the literature.

Case presentation: We reported a case of PTC-FMS found in a 41-year-old Italian woman, who came to our Institute with a recent growth in the form of a mass on the neck. Further immunohistochemical examination showed β-catenin aberrant staining both in the nuclei and cytoplasm of the mesenchymal cells. The patient underwent total thyroidectomy and received radioactive iodine (RAI) 2 months after surgery.

Conclusion: Given the possibility of recurrence of PTC-FMS and the ineffectiveness of RAI therapy, complete surgical resection represents the main treatment for this type of tumor. Despite the fact that the specific nature of these lesions has yet to be determined, guidelines for classical PTC should be followed.

Keywords: Desmoid tumor; Fibromatosis-like stroma; Nodular fasciitis-like stroma; Papillary thyroid carcinoma; β-catenin aberrant staining.

Fig. 1

Hematoxylin eosin stain showing two intermingled components of the tumor, the epithelial component (right) with a focus of papillary thyroid carcinoma and the stroma (left) consisting of spindled-shaped cells arranged in fascicles (H&E: original magnification 100x)

Fig. 2

Immunohistochemical staining for beta-catenin showing diffuse nuclear and cytoplasmic reactivity in the stromal component (left), whereas the epithelial component demonstrates diffuse membrane positivity and nuclear negativity (left) (original magnification 100x)

Fig. 3

Immunohistochemical staining for TTF1 showing strong nuclear positivity in the epithelial component (right), while the stromal component is negative (left) (original magnification 100x)

Fig. 4

Immunohistochemical staining for PAX8 showing strong nuclear positivity in the epithelial component (right), while the stromal component is negative (left) (original magnification 100x)

Fig. 5

Immunohistochemical staining for BRAF V600E showing strong nuclera positivity in the epithelial component (right), while the stromal component is negative (left) ( magnification 5x)