Enlarged solitary necrotic nodule of the liver misinterpreted as a metastatic liver cancer.

Solitary necrotic nodule of the liver is a rare nonmalignant lesion of unknown etiology. It is defined as a nodule with a completely necrotic core enclosed by a hyalinized fibrotic capsule containing elastic fiber. We report a 74-year-old woman with a solitary necrotic nodule of the liver that mimicked metastasis from a previous rectal adenocarcinoma. She was referred to us for an asymptomatic liver nodule in segment 8 that had increased in diameter from 5 to 15 mm over the past 8 months. Ultrasonography showed a well-defined, oval, hypoechoic mass, and computed tomography showed a hypodense area without contrast enhancement except for a ring-like enhancement during hepatic arteriography. Magnetic resonance imaging revealed a mass that was hypointense on T1-weighted imaging and slightly hyperintense on T2-weighted imaging. The patient underwent hepatectomy of segment 8. The resected specimen contained an oval nonencapsulated nodule with firm and gritty consistency and a well-defined margin. Histologic findings were compatible with those of solitary necrotic nodule. Clinicians should recognize the existence of this lesion as one of the differential diagnoses of metastatic liver nodule. Solitary necrotic nodules can change size, and when enlarged, differentiation from metastasis is extremely difficult.