A case of multiple hepatic angiomyolipomas with high (18) F-fluorodeoxyglucose uptake

Abstract

Background: Hepatic angiomyolipoma is a rare benign mesenchymal tumor. We report an unusual case of a patient with multiple hepatic angiomyolipomas exhibiting high (18) F-fluorodeoxyglucose (FDG) uptake.

Case presentation: A 29-year-old man with a medical history of tuberous sclerosis was admitted to our hospital for fever, vomiting, and weight loss. Abdominal dynamic computed tomography revealed faint hypervascular hepatic tumors in segments 5 (67 mm) and 6 (10 mm), with rapid washout and clear borders; however, the tumors exhibited no definite fatty density. Abdominal magnetic resonance imaging revealed that the hepatic lesions were slightly hypointense on T1-weighted imaging, slightly hyperintense on T2-weighted imaging, and hyperintense with no apparent fat component on diffusion-weighted imaging. FDG-positron emission tomography (PET) imaging revealed high maximum standardized uptake values (SUVmax) of 6.27 (Segment 5) and 3.22 (Segment 6) in the hepatic tumors. A right hepatic lobectomy was performed, and part of the middle hepatic vein was also excised. Histological examination revealed that these tumors were characterized by the background infiltration of numerous inflammatory cells, including spindle-shaped cells, and a resemblance to an inflammatory pseudotumor. Immunohistochemical evaluation revealed that the tumor stained positively for human melanoma black-45. The tumor was therefore considered an inflammatory pseudotumor-like angiomyolipoma. Although several case reports of hepatic angiomyolipoma have been described or reviewed in the literature, only 3 have exhibited high (18) F-FDG uptake on PET imaging with SUVmax ranging from 3.3-4.0. In this case, increased (18) F-FDG uptake is more likely to appear, particularly if the inflammation is predominant.

Conclusion: Although literature regarding the role of (18) F-FDG-PET in hepatic angiomyolipoma diagnosis is limited and the diagnostic value of (18) F-FDG-PET has not yet been clearly defined, the possibility that hepatic angiomyolipoma might exhibit high (18) F-FDG uptake should be considered.

Figure 1

Abdominal computed tomography. (A) Axial computed tomography (CT) imaging shows a liver lesion (arrow) with low attenuation. (B) On early-phase axial contrast-enhanced CT imaging, the lesion exhibits heterogeneous enhancement. (C) On portal-phase axial contrast-enhanced CT imaging, the lesion shows rapid washout in segment 5. (D) The segment 6 lesion exhibits a similar pattern (arrowhead).

Figure 2

Abdominal magnetic resonance (MR) imaging. Abdominal magnetic resonance (MR) imaging revealed that the hepatic tumors (segment 5: arrow, segment 6: arrowhead) were slightly hypointense on T1-weighted imaging (WI), slightly hyperintense on T2WI, and hyperintense without an apparent fat component on diffusion-weighted imaging.

Figure 3

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging of hepatic angiomyolipomas. The fused PET/CT image demonstrates the markedly increased FDG uptake in segments 5 and 6 of the liver.

Figure 4

Histological features of hepatic angiomyolipomas. (A, B) Histological examination revealed the background infiltration of numerous inflammatory cells, including spindle-shaped cells (A: original magnification = 20×, scale bar = 50 μm, B: 40×, scale bar = 100 μm; hematoxylin–eosin staining). (C) The immunohistochemical analysis revealed positive staining for human melanoma black-45 (HMB-45; original magnification = 20×, scale bar = 50 μm). (D) In a gross examination, the cut AML surfaces revealed well-delineated borders and slightly variegated appearances.