Solitary necrotic nodule of the liver

1 Department of Surgery, Rinku General Medical Center, Izumisano Municipal Hospital, 2-23, Rinku Orai-Kita, Izumisano, Osaka 598-8577, Japan 2 Department of Internal Medicine, Rinku General Medical Center, Izumisano Municipal Hospital, Osaka, Japan 3 Department of Radiology, Rinku General Medical Center, Izumisano Municipal Hospital, Osaka, Japan 4 Department of Pathology, Rinku General Medical Center, Izumisano Municipal Hospital, Osaka, Japan

2][3][4][5][6] Another unsolved problem in the clinical setting is that the differential diagnosis of these lesions is not immediate or certain, because these lesions have ultrasound and radiographic patterns similar to those of metastatic lesions. 7,8Preoperative features on ultrasound and radiographic examinations have previously been reported in only 3 cases of these lesions; features on preoperative magnetic resonance imaging (MRI) examinations have been reported in only 2 cases. 7,8Specific patterns of this lesion on preoperative examinations have not yet been identified.It would be important for surgeons to recognize the existence of this benign hepatic lesion to determine the best and most suitable diagnostic strategy and therapeutic management.We report herein a case of solitary necrotic nodule of the liver and describe the preoperative features on MRI examination.

Case report
On December 13, 1999, a 48-year-old woman was referred to our hospital with elevated serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)19-9 levels and a hepatic lesion incidentally detected on ultrasound examinations.Her past history was unremarkable.Laboratory test results were normal (Table 1), except for elevated serum levels of CEA and CA19-9.The serum CEA level was 9.0ng/ml (normal, Ͻ5ng/ml), and the serum CA19-9 level was 291 U/ml (normal, Ͻ37 U/ml).The serum α-fetoprotein level was normal.An ultrasound scan showed the presence of a hypoechoic area without a halo, measuring 2.0 cm, in Couinaud's segment VIII of the liver; suggesting a metastatic mass lesion (Fig. 1a).A CT scan confirmed the presence of a hypodense rounded formation, measuring 2cm in diameter; the characteristics of the lesion on CT scan seemed to indicate a cystic mass (Fig. 1b).Significant enhancement was not recognized during the Abstract Solitary necrotic nodule of the liver is a rare benign lesion; only 22 cases have been reported to date.An unsolved problem in treating these lesions involves the difficulties in differential diagnosis; specific features of necrotic nodule of the liver in preoperative examinations have not been identified.Here, we report a patient with resected solitary necrotic nodule of the liver with preoperative features shown on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) examinations.A 48-year-old woman was referred to our hospital on December 13, 1999 because a hypoechoic lesion in Couinaud's segment VIII of the liver had been incidentally detected on US.A CT scan confirmed the presence of a round hypodense lesion, measuring 2 cm in diameter.No significant enhancement was recognized on dynamic MRI study.T1-Weighted MRI examinations demonstrated a low intensity showing a triplelayered pattern with low-iso-low intensity in the lesion, while T2-weighted images demonstrated a slightly high intensity in the lesion.These features suggested fibrous tissue.Histological examinations following partial resection of the liver revealed a solitary necrotic nodule of the liver.Combination studies, including MRI examinations, would be useful for the preoperative diagnosis of a solitary necrotic nodule of the liver.

Introduction
Solitary necrotic nodule of the liver is a rare benign hepatic lesion, initially described by Shepherd and Lee 1 in 1983; only 22 cases have been reported to date.The etiology of the lesion remains uncertain, although a few possible pathogenetic mechanisms have been dis-Offprint requests to: K. Iwase Received: June 1, 2001 / Accepted: November 16, 2001 early or delayed phase on dynamic MRI examinations (Fig. 2).T1-Weighted MRI examinations demonstrated a triple-layered pattern with low-iso-low intensity, while T2-weighted images demonstrated a slightly high intensity in the lesion (Fig. 3).These features suggested fibrous tissue with hypovascularity, rather than neoplasms.Percutaneous needle biopsy was not successful because of the location of the lesion.On fiberoptic esophagogastroscopy and pancolonoscopy, there was

Fig
Fig. 1. a Ultrasound scan showed the presence of a hypoechoic area.b Computed tomography (CT) scan confirmed the presence of a hypodense rounded lesion

Table 1 .
Laboratory data on admission