PMC6313948_01
(A) Axial contrast-enhanced CT image showing a heterogeneous, large mass, occupying the surgical bed. (B) Corresponding axial T2-weighted MRI revealed a heterogeneous signal intensity mass, with cystic/necrotic spaces, areas of hemorrhage exhibiting a 'shading effect' (arrow), with (C) matching hyperintensity areas on T1 fat-saturated, unenhanced 3D GRE image (arrow). (D) The MRI also showed heterogeneous enhancement of the predominately solid areas of the tumor (arrow) and (E) infiltration of the splenic capsule (arrow). GRE, gradient echo; MRI, magnetic resonance imaging; CT, computed tomography.
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The mass lay adjacent to the psoas muscle and the spleen, and caused elevation of the left hemidiaphragm (Fig. 1A). A relatively circumscribed large mass, sized 14x12x13 cm, was noted at the anatomic site of the resected left kidney (Fig. 1B, C and D), with evident infiltration of the spleen (Fig. 1E).
(A and B) Histological re-examination of the primary tumor demonstrated characteristics of an AML, with proliferation of predominantly round to polygonal epithelioid cells with enlarged vesicular nuclei and prominent nucleoli (H&E staining; magnification, x100). Histological examination of the locally recurrent EAML demonstrated (C) more extensive epithelioid characteristics with atypia (H&E; magnification, x100), (D) invasion of the spleen (H&E staining; magnification, x100) and expression of (E) Melan-A and (F) HMB-45 in tumor cells (magnification, x200). H&E, hematoxylin and eosin; AML, angiomyolipoma; EAML, epithelioid AML.
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CT scan of the chest did not reveal any pulmonary abnormalities. CT-guided core needle biopsy of the large mass and revision of the histology of the nephrectomy revealed an EAML (Fig. 2A and B). The large tumor was 17x11x9 cm in size, had large areas of necrosis and was composed of epithelioid cells with 2 mitoses per 10 high-power fields (Fig. 2C). The tumor infiltrated the spleen (Fig. 2D) and the mesocolon, but not the colon itself, the diaphragm or the psoas muscle microscopically. Immunohistochemical staining was negative for cytokeratin (MNF116), epithelial membrane antigen, CD10, desmin and c-kit, while the epithelioid cells were focally positive for Melan A (Fig. 2E), human melanoma black (HMB)-45 (Fig. 2F) and S-100.
(A) Mesenteric infiltrating mass (arrow) exhibiting the same imaging properties as the locally recurrent mass, with (B) heterogeneity on sagittal T2-weighted MRI, with areas of necrosis and heterogeneous enhancement on axial T1 fat-saturated 3D GRE images. (C) Half-Fourier acquisition single-shot turbo spin-echo depicted moderately high signal intensity of the focal liver lesion in liver segment VIII, (D) restricting diffusion on diffusion weighted imaging, ADC map (arrow), suggesting malignant, metastatic liver lesion. GRE, gradient echo; ADC, apparent diffusion coefficient; MRI, magnetic resonance imaging.
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The imaging characteristics of the 4-cm lesion at the left side of the pelvis were similar to those of the large mass and it was considered to be a peritoneal metastasis (Fig. 3A and B). A 3.1-cm metastatic lesion was also found in segment VIII of the liver, along with multiple small cysts (Fig. 3C and D).