PMC6407075_01
Breast imaging. Mammography suggested a lobulated, radiopaque lesion with mostly sharp contours and hallo sign (A,B). Breast ultrasonography revealed an round-shaped, low-echoic tumor of unclear etiology (C) with a pathological pattern of blood flow, as seen on Power-Doppler imaging (D).
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Mammography suggested a lobulated, radiopaque 1.5-cm lesion with mostly sharp contours and halo sign (Fig. 1A,B). Breast ultrasonography revealed an round-shaped, low-echoic tumor of unclear etiology (Fig. 1C) with a pathological pattern of blood flow, as seen on Power-Doppler imaging (Fig. 1D).
Histologic and cytogenetic evaluation. The tumor is composed of admixture of microcystic, ductal and solid patterns (A). Histologic hallmark is the presence of abundant intra- and extracellular dense pink PAS positive secretions, especially in microcystic extracellular spaces (B). Immunohistochemisty showed positive results for c-Kit protein (C), and cytokeratins 5,14 (D). FISH analysis by break-apart probe showed detected break of gene NTRK3 (15q25.3). Fusion of yellow (orange-yellow-green) signals demonstrates one of an intact copy of gene NTRK3, split orange and green signals indicate a break in the second copy of NTRK3 gene (E). Schematic visualisation of detected fusion transcript ETV6-NTRK3 together with the annotation of fusion partners and information about the depth of reading of studied area including particular reads (F).
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Histological evaluation of the surgical specimens showed monoform tumor cells with eosinophilic cytoplasm with vacuoli and thyroid-like pseudofolicles, round nuclei with intermediate mitotic activity (MAI 10 MF/10 HPF) (Fig. 2A). The immunohistochemistry (IHC) showed periodic acid-Schiff (PAS) positive secretory material in intra- and extracellular spaces (Fig. 2B) and negative results for estrogen, progesteron and HER2 receptors. The tumor was positive for cytokeratins 5, 14 and c-Kit protein (CD117) (Fig. 2C,D). A dual color break apart probe (SureFISH , Agilent, St.Clara, USA) was used for fluorescence in situ hybridization (FISH) evaluation of NTRK3 (15q25.3) gene (Fig. 2E). Next generation sequencing (NGS) analysis was used for schematic visualisation of detected fusion transcript ETV6-NTRK3 together with information about the depth of reading of studied area (Fig. 2F).