Hepatocellular Adenoma (HCA) is a benign monoclonal tumor originating from mature hepatocytes [2]. It typically presents with nonspecific symptoms, and is most commonly seen in women aged between 20- and 50-years taking estrogen-based contraceptives [3]. The diagnosis is usually done incidentally on abdominal imaging [1].

It occurs predominantly in women of reproductive age, with a reported female: male ratio of 10:1 [1]. HCA is also associated with genetic syndromes, including glycogen storage disease type I and type III, with frequencies of 22–75% and 25%, respectively, and familial adenomatous polyposis [1,4,5].

Rarer associations include MODY3 diabetes and McCune-Albright syndrome [5], as well as conditions involving high levels of endogenous androgens or estrogens. In recent years, metabolic syndrome and obesity are also emerging as risk factors [1].

The molecular classification identifying 4 subtypes of adenomas where the B-catenin mutated subtype accounts for 10%-15%. B-catenin mutations have also been identified in hepatocellular carcinomas related to hepatitis C virus infections. These mutations are associated to an increased risk of bleeding and malignant transformation [6].

The clinical presentation is heterogeneous. Most HCA is found incidentally on abdominal imaging. When they are symptomatic, the most common presentation is mild and nonspecific right hypochondrial pain, observed in 37% of patients. However, the pain may be severe as a result of bleeding [7].

While hemorrhage is an infrequent complication associated with hepatic tumors, HCA ranks as the second most prevalent tumor connected with bleeding, following hepatocellular carcinoma (HCC), with up to 30% of HCA patients experiencing spontaneous bleeding [1]. When bleeding occurs, it may be intratumoral or the tumor may rupture, leading to subcapsular or intraperitoneal hemorrhage presenting as an acute hemoperitoneum. Hemodynamic instability occurs in fewer than 10% of cases and is more commonly observed in patients with intraperitoneal bleeding rather than intratumoral bleeding, in contrast to the presented case [1].

Rupture is more likely in patients with large (>5 cm), solitary, and superficial tumors. Additional risk factors include inflammatory subtype, hormone use, and pregnancy [8]. Our patient presented multiple risk factors associated with a higher bleeding risk, namely, the size, hormone use, and HCA subtype.

HCA also has a risk of malignant transformation. Surgical series report a 4–10% incidence of HCC within resected adenomas. Known risk factors include activating mutations in β-catenin, occurring in up to 5–10% of cases, male gender, and tumor diameter larger than 5 cm [1].

Recent advancements in contrast-enhanced magnetic resonance imaging (MRI) have enhanced the role of imaging in diagnosing hepatocellular adenomas (HCAs), particularly in identifying specific subtypes and distinguishing them from other diagnosis [9].

The MRI appearance often exhibit hyperintense, heterogeneous signals on T1- and T2-weighted images due to intratumoral lipids that help to differentiate them from focal nodular hyperplasia (FNH). Hemorrhagic HCAs may also demonstrate hyperintense T1 signals with subcapsular hemosiderin rings [10,11].

Specialized MRI contrast agents enhance lesion characterization. Kupffer cell–specific agents—such as superparamagnetic iron oxides (SPIOs) and ultra-small SPIOs (USPIOs)—typically show no uptake in HCAs due to the absence of endothelial-reticular cells, resulting in decreased T2 signal intensity. Gadolinium-enhanced dynamic gradient-echo MRI may reveal early arterial enhancement and peritumoral vessels, which are characteristic of HCA [12,13].

Others MRI contrast agents, like gadoxetic acid was found to be the most cost-effective approach in a 2018 study, although its diagnostic accuracy was comparable to conventional MRI [14].

On non-contrast CT scans, HCAs typically present as well-circumscribed, low-density masses without lobulated contours and reveals after contrast agents’ injection an early peripheral enhancement with a centripetal filling pattern during the portal venous phase, which usually transitions to isodensity in the portal or delayed phase. Although uncommon, central necrosis or calcifications may also be observed [12,15].

To aid in the evaluation of incidental liver lesions detected during CT scans performed for unrelated reasons, the American College of Radiology (ACR) has developed an algorithm for use in asymptomatic adults (≥18 years old). This algorithm is stratified based on the patient's risk level for hepatic malignancy (low vs. high). However, it is not intended for cases where CT was ordered to assess known or suspected hepatic pathology. Additionally, if associated findings such as vascular invasion, biliary dilation, or adenopathy are present, direct referral for oncologic evaluation is recommended [16].

Hepatic adenomas smaller than 5 cm and associated with oral contraceptive use are typically managed conservatively by discontinuing oral contraceptives, combined with regular imaging follow-up [17].

For surveillance, and according to the 2024 American College of Gastroenterology (ACG) guidelines, women with HCAs smaller than 5 cm should undergo computed tomography (CT) or magnetic resonance imaging (MRI) every 6 to 12 months for at least two years. After that, ultrasound may be considered for ongoing surveillance; however, contrast-enhanced CT or MRI remains necessary if any changes in the adenomas are detected [17].

Surgical resection, which does not require wide surgical margins or regional lymphadenectomy, is recommended for all male patients regardless of tumor size, and for women with tumors larger than 5 cm [18].

Transarterial Embolization (TAE) is the preferred treatment for HCAs complicated by hemorrhage and may be followed by elective surgical resection [19].

Radiofrequency ablation (RFA) is typically considered for adenomas smaller than 4 cm and is reserved for non-surgical candidates, those with hormone-sensitive tumors, underlying liver disease, or women planning pregnancy [19].