Are liver nested stromal epithelial tumors always low aggressive?

Figure 1 Computer tomography examination and virtual resection. A: Pre-contrast acquisition, axial image cranial to the hilar plane showing a large, hypo-attenuating lobulated lesion involving the right hemi-liver and part of the segment 4 (white circle: calcification within the neoplastic lesion); B and C: Axial images across the hilar plane during arterial (B) and portal (C) phase. Then neoplastic, lobulated lesion shows early arterial enhancement resulting in hypo-attenuation during the portal phase. The right portal branch is not visible due to neoplastic infiltration (white arrows); D-F: Virtual resection, volume renderings of CT images; D: Total liver volume; the non-homogenous red color of the right hemi-liver corresponds to the lesion (black arrows); E: Tumor lesion; F: Future remnant liver corresponding to segments 2 and 3.

Figure 2 Intra-operatory images and tumoral tissue.

Figure 3 Grossly, right hepatic lobe was almost entirely occupied by a well-circumscribed multinodular mass with homogeneous, whitish cut surface and with calcification areas. In detail, macroscopic neoplastic vascular invasion of a portal vein branch.

Figure 4 Tumor showing organoid appearance with well-demarcated nests in a myofibroblastic stroma (A). B: Areas of osseous metaplasia and calcifications; C: Epithelioid and spindle cellular nests with bile ducts entrapped in fibrous stroma; D: Epithelioid and spindle-shape cells with eosinophilic and clear cytoplasm.

Figure 5 Immunohistochemical stains showing neoplasm negativity for hepatocyte paraffin 1 (EpPar1) (counterstained normal liver parenchyma), negativity for CK7 (highlighted entrapped bile ducts between the tumor cell), stromal positivity for ACML and positivity for β-catenin (both membrane and nuclear).

Figure 6 Computer tomography scan. A: CT scan performed in November 2015 showing the sacral lesion; B: CT scan performed in April 2016 showing increase of the sacral lesion; C: CT scan performed in November 2015 showing liver lesions; D: CT scan performed in April 2016 showing increase of liver lesions. CT: Computer tomography.