Papillary Carcinoma of the Thyroid Gland with Nodular Fasciitis-like Stroma
A 49-year-old woman presented with a lump in her neck, which had gradually increased in size during the previous two months. Physical examination revealed a firm nodular mass in the right lobe of the thyroid gland. Her past medical history was unremarkable. Thyroid function tests were within normal range. Ultrasonography revealed a round, relatively well-defined, mixed echoic nodule in the right lobe. The nodule had a markedly hypoechoic portion in the lateral side and had a slightly hypoechoic portion in the medial side. Color Doppler imaging showed increased blood flow within the markedly hypoechoic portion of the nodule ().\nThe fine needle aspiration in this nodule exhibited clusters of cuboidal cells with features of papillary carcinoma. The smear also contained spindle cell groups with non-cohesive arrangement among the tumor cells of PTC. The spindle cells were in a pale to eosinophilic background with associated lymphocytic infiltrate. They had vesicular nuclei, small nucleoli, and indistinct cytoplasmic membrane. Neither significant atypia nor mitotic figures were identified (). Total thyroidectomy with central lymph node dissection was performed.\nGrossly, the right lobe of the thyroid gland showed a well-circumscribed yellow to white, partially encapsulated mass, measuring 2.3×2.0×1.8 cm. Histologically, the tumor consisted of two distinct components: stromal and epithelial. The stromal component consisted of spindle-shaped cells arranged in interlacing fascicles and an abundant fibromyxoid matrix accompanied by thick collagen fibers. The stromal cells had neither nuclear atypia nor mitotic figures. Occasional lymphocytic infiltration or extravasated red blood cells were also identified in the center and periphery of the tumor stroma. Epithelial components had features of PTC (). The tumor was confined to the thyroid parenchyma. Metastatic tumor tissue was detected in four of five resected central lymph nodes without stromal components. Immunohistochemically, the spindle cells exhibited focal cytoplasmic staining with desmin and diffuse cytoplasmic stain with smooth muscle actin. In contrast, they showed negative staining with cytokeratin and thyroglobulin. These findings are consistent with previous reports of PTC-NFS.\nWe further performed immunohistochemical analyses of β-catenin, transforming growth factor-β (TGF-β), Smad-2 and -4, and matrix metalloproteinase (MMP)-3 and -9, which have been reported to be useful in distinguishing FM from NF. The immunostaining results for the stromal spindle cells are summarized in . The spindle cells showed nuclear and cytoplasmic β-catenin expression and cytoplasmic TGF-β expression. Smad-2 and -4 were also localized in the nuclei of the spindle cells. In contrast, the spindle cells lacked MMP-3 expression and showed scant cytoplasmic staining with MMP-9 ().