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

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.

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.

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.