Peliosis hepatis was first described by Wagner in 1861 and named by Schoenlank in 1916. The first description in the English-language literature was published by Zak in 1950 [4]. Peliosis hepatis is characterized by a diffuse distribution of irregularly shaped hemorrhages (1–10 mm in diameter) within the hepatic parenchyma [5]. Although its pathogenesis is unclear, various forms of endothelial cell damage in the sinusoids lead to their dilatation, known as Disse’s cavity, which fills with blood and results in the destruction of the sinusoids [6]. The etiology of peliosis hepatis is unknown in 25–50% of cases [7], but the use of certain drugs (azathioprine, oxaliplatin, oral contraceptives, steroids), infections (tuberculosis, HIV), hematological malignancies, and renal transplantation are reportedly associated with it [8,9,10]. In the present case, the patient had pStage IIIb, received CAPOX as postoperative adjuvant chemotherapy, and underwent a hepatectomy after contrast-enhanced CT demonstrated a solitary mass in the liver suggestive of a metastatic liver tumor. The mass lesion demonstrated severe, localized, sinusoidal dilatation and congestion. Oxaliplatin-induced endothelial cell damage was suspected to be the cause, because blue liver caused by sinusoidal dilatation is a known adverse effect of oxaliplatin. Anecdotally, diffuse peliosis hepatis is associated with blue liver, but cases like the present one, which was difficult to distinguish from a metastatic liver tumor because of its localized formation and required a hepatic resection for a definitive diagnosis, are extremely rare [11].

There are few reports describing the findings typical of peliosis hepatis on imaging studies, such as CT and ultrasound. The characteristics of the condition are not yet well known but may include heterogeneous hypoechoic to isoechoic areas on abdominal ultrasound; low attenuation and internal heterogeneity in the late arterial and portal phases on contrast-enhanced CT [12]; low signal intensity on T1-weighted MRI; high signal intensity on T2-weighted MRI; and rich vessel presence in the arterial phase [13]. However, a differential diagnosis based on imaging studies is challenging because both peliosis hepatis and liver metastasis have varied presentations. Although the preoperative images in the present case were not typical of metastatic liver tumors, no PET–CT was performed. Peliosis hepatitis is usually isometabolic, whereas metastatic liver tumors tend to have increased uptake of 18F-FDG [14]. Therefore, PET–CT might have contributed to the differential diagnosis in the present case.

Although peliosis hepatis is definitively diagnosed on the basis of histopathological findings, the risk of bleeding is high even with ultrasound or CT-guided biopsy owing to the vascularity of the lesion, and occurrences of a life-threatening hemorrhagic shock after CT-guided biopsy have been reported [15]. While a previous study diagnosed peliosis hepatis on the basis of laparoscopic liver biopsy findings [13], the present case was preoperatively indistinguishable from a metastatic liver tumor and required a liver resection for definitive diagnosis.

Diagnosing localized, solitary peliosis hepatis developing after oxaliplatin administration, as in the present case, is difficult without a hepatectomy [16]. However, if the imaging studies of a patient who has received oxaliplatin-based chemotherapy demonstrate features that are typical of a liver metastasis, peliosis hepatis should be included in the differential diagnosis.