PMC5943089_01
(A) Unenhanced CT scan shows a mass (white arrow) with necrosis (white triangle) in the left kidney. (B-D) On contrast-enhanced CT images, the tumor presents progressive and heterogeneous enhancement. CT = computed tomography.
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F1
Preoperative noncontrast CT scan of the abdomen revealed a 6.0 x 5.2 x 7.0 cm oval mass with heterogeneous density (CT value, 17-40 HU), located in the left kidney (Fig. 1A). The mean CT values were 53 HU, 63 HU, and 67 HU at the arterial, portal venous, and delayed phases, respectively (Fig. 1B-D).
CT angiography does not reveal any tumor feeding vessels or vascular malformation. CT = computed tomography.
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F2
CT angiography (CTA) did not reveal any tumor feeding vessels or vascular malformation (Fig. 2).
(A-C) The tumor presents as low to high signal on T1WI and T2WI with slightly diffusion restriction.
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F3
T1-weighted images, low-to-high signal intensity on T2-weighted images and complete capsule with distinct edges (Fig. 3A and B). The lesion exhibited low-to-intermediate signal intensity on the diffusion-weighted images (Fig. 3C).
Ultrasonography of the abdomen shows increased blood flow signal around the hypoechoic mass. LK = left kidney, M = mass.
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F4
Ultrasonography (Fig. 4) of the abdomen demonstrated a solid mass occupying the lower middle portion of the left kidney.
(A) The tumour is comprised of the proliferation of predominantly epithelioid cells with granular eosinophilic cytoplasms (H&E, x100). (B) Immunostain for human melanoma black 45 in tumor cells. (C) Immunohistochemical stain for Melan-A. (D) The proliferation index, expressed as a percentage of Ki-67 antigen-positive nuclei, is around 10%.
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F5
Microscopically, the mass consisted of a large quantity of proliferative epithelioid cells with abundant eosinophilic cytoplasm and pleomorphic nuclei (Fig. 5A). The immunostaining (Fig. 5B and C) showed that the tumor cells were positive for melanocytic markers [human melanoma black 45 (HBM-45) and Melan-A], cluster of differentiation 117 (CD 117) and negative for smooth muscle actin (SMA), desmin, cytokeratin 7 (CK 7), paired box gene 8 (PAX8), pan-cytokeratin, and S-100. The proliferation index, expressed as a percentage of Ki-67 antigen-positive nuclei, was around 10% (Fig. 5D).