From a Suspicious Liver Mass to Splenosis: A Case Report.

Splenosis refers to the uncommon phenomenon of heterotopic autoimplantation of splenic tissue within the abdominopelvic or thoracic cavities, typically observed in patients with a history of splenic trauma or surgery. Intrahepatic splenosis is an even rarer occurrence, with its pathophysiology attributed to the "seeding" of splenic pulp fragments into the liver following splenic injury. Alternatively, a hematogenous spread of splenic cells through the splenic veins may also contribute to hepatic implantation. This condition is often asymptomatic and is usually detected incidentally. The absence of specific radiological characteristics makes its diagnosis particularly challenging, as it can be easily mistaken for other hepatic masses, including adenomas or hepatocellular carcinoma. This case report highlights such a diagnostic challenge. A 51-year-old male patient was referred for further investigation of a well-circumscribed, homogeneous solid liver lesion, incidentally detected during a routine abdominal ultrasound (US) and initially suspected to be focal nodular hyperplasia (FNH). The patient was asymptomatic, with no palpable abnormalities on physical examination. His past medical history included hepatitis B, systemic arterial hypertension, dyslipidemia, nephrolithiasis, and an urgent splenectomy performed a decade earlier due to traumatic rupture. Laboratory tests revealed a mild elevation in liver transaminases, without signs of cholestasis. Immunologic and microbiological analyses ruled out acute hepatitis B. To further assess the hepatic lesion, abdominal magnetic resonance imaging (MRI) was performed, revealing two nodular formations in segments II and III. The lesion appears homogeneous and isointense compared to the liver parenchyma on both T2- and T1-weighted images, with no signal drop observed on T1 out-of-phase sequences. During dynamic imaging following gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) administration, the lesion demonstrates intense homogeneous enhancement in the arterial phase, with no washout observed in the portal phase or the 10-minute equilibrium phase, findings suggestive of β-catenin-mutated adenoma, which carries a risk of malignant transformation. Given this concern, after evaluating the operative risk, surgical intervention was recommended. The patient underwent exploratory laparoscopy, during which both lesions were enucleated with clear margins. The postoperative period was uneventful, and he was discharged the following morning. Histopathological examination confirmed the presence of heterotopic splenic tissue within the liver, with no signs of malignancy. This report underscores the importance of considering intrahepatic splenosis in the differential diagnosis of hepatic nodules, particularly in patients with a history of splenectomy, especially when lesions are located near the liver capsule.