PMC7728115_01
Fine-needle aspiration cytology. First study: (A) Groups and microfollicles of clear balloon-shaped cells showing abundant fine vesicles in their cytoplasm. Second study: (B) A cluster and a microfollicle of clear balloon-shaped cells can be seen - nuclei are round with a visible nucleolus; (C) A microfollicle is displaying a central lumen - there is slight anisokaryosis. Papanicolaou (Pap) staining: (A-C) x400
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F1
There were groups of clear cells or microfollicular structures with a diffusely vacuolated cytoplasm (Figure 1A). Based on these findings the successive diagnoses in two samples were follicular neoplasia (Figure 1, B and C).
Total thyroidectomy. The right lower lobe contains a 2 cm diameter, solid, pale tan, nodular lesion
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F2
The right lower lobe contained a 2 cm diameter encapsulated, solid, pale tan, fleshy, nodular lesion (Figure 2).
Histopathology of the follicular adenoma with clear cell change: (A) Well-circumscribed lesion with a thin smooth capsule of fibrous connective tissue; (B) Trabeculae and solid nests of clear balloon-shaped cells containing fine vesicles - many nuclei are central, hyperchromatic and show a single nucleolus. Hematoxylin-Eosin (HE) staining: (A and B) x400
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F3
The nodular lesion of the right lobe was well circumscribed, with a thin smooth capsule of fibrous connective tissue (Figure 3A). The cells were grouped in solid areas showing a diffuse, trabecular, or nesting pattern of growth (Figure 3B) with occasional formation of microfollicular structures with central lumen surrounded by clear cells (Figure 4A).
Architecture of the follicular adenoma with clear cell-change: (A) Microfollicular architecture, structures with a central lumen are surrounded by clear cells - scant amount of colloid shows pale eosinophilic staining; (B) Central lumina are occupied by PAS-positive colloid - the PAS staining accentuates the cytoplasmic granularity produced by the confluence of fine cytoplasmic vesicles. Hematoxylin-Eosin (HE) staining: (A) x400. Periodic Acid-Schiff (PAS) staining: (B) x400
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F4
The cells were grouped in solid areas showing a diffuse, trabecular, or nesting pattern of growth (Figure 3B) with occasional formation of microfollicular structures with central lumen surrounded by clear cells (Figure 4A). The lumens contained PAS-positive colloid (Figure 4B). The PAS staining accentuated the cytoplasmic granularity (Figure 4B) and this reaction was diastase resistant indicating the absence of glycogen.
IHC reactivity of the follicular adenoma with clear cell change. The clear balloon-shaped cells show positivity for pan-CK AE1/AE3 (A, x200), TGB (B, x400), PAX8 (C, x400), and TTF-1 (D, x400). IHC: Immunohistochemical; Pan-CK: Pan-cytokeratin; TGB: Thyroglobulin; PAX8: Paired box gene 8 protein; TTF-1: Thyroid transcription factor-1
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F5
The IHC panel revealed the tumor cells positive for pan-cytokeratin (CK) AE1/AE3 (Figure 5A), thyroglobulin (TGB) (Figure 5B), paired box gene 8 protein (PAX8) (Figure 5C), and thyroid transcription factor-1 (TTF-1) (Figure 5D), whereas no immunoreactivity was seen for renal cell carcinoma marker (RCCM), cluster of differentiation 10 (CD10), carbonic anhydrase IX (CAIX), anti-mitochondrial antibody (AMA), PTH, p53 protein, anti-human melanosome [human melanoma black 45 (HMB45)], S100 protein, and smooth muscle actin (SMA).