1. Introduction
2. Case Presentation
MRI was performed using the 3.0-T system. A, An axial early (2 min) contrast-enhanced T1-weighted image after bolus administration of gadolinium-based contrast shows 7 cm in size, irregularly shaped, homogeneous enhancing masses with spiculated margins across the left upper outer quadrant and lower outer quadrant. B, An axial subtraction image of the left breast shows the masses with early enhancement. C, These masses show rapid washout in the reverse subtraction image. D - F, Images of the right breast in the same sequence as the left breast show a 0.8 cm, lobular, homogeneous enhancing mass with smooth margins in the subareolar area and a 0.8 cm, round, central enhancing mass with irregular margins in the right upper center. These masses show early enhancement but no washout in the reverse subtraction image.
Solid papillary carcinoma (SPC) with invasion in the right breast at 12 o’clock position. A, Circumscribed, large cellular nodules are found (H & E staining × 1.25). The size of the SPC in situ is 0.9 × 0.8 × 0.5 cm and the size of the invasive SPC located immediately adjacent to the SPC in situ is 0.5 × 0.4 × 0.4 cm. Therefore, about 70% of the total tumors are SPC in situ component with pushing boundaries (arrows), the other 30 % is invasive SPC with infiltrative border (arrowheads). B, The cellular proliferation is homogeneous and cohesive, lacking obvious papillary architecture. The cell shape is polygonal. Cytoplasm is moderate in amount and finely granular eosinophilic (H & E staining × 20). C, The cellular nests appear invasive because of their presence of a geographic jigsaw pattern with more ragged and irregular margins (H & E staining × 10). D, Immunohistochemical evidence of neuroendocrine differentiation, consisting of staining for synaptophysin, is observed (× 20).
Solid papillary carcinoma (SPC) with invasion in the left breast. A, Scanning magnification of breast tissue showing multiple circumscribed cellular masses comprised of closely apposed, expanded and solidified round structures arranged in contiguous, embedded in dense fibrous stroma (H & E staining × 1.25). The boundaries of the entire tumor of 6.6 × 3.5 × 2.5 cm are infiltrative border (arrows). SPC in situ component is about 60% of the total left breast tumors, which lie between intratumoral and peritumoral. B, Obvious invasive growth of the conventional infiltrative type are found (H & E staining × 20). C, Immunohistochemistry for smooth-muscle myosin heavy chain (Smm-hc) shows complete absence of a peripheral myoepithelial lining around the cellular nodules (H & E staining × 10).






