Solitary Necrotic Nodules of the Liver: Histology and Diagnosis With CT and MRI

Abstract

Background: A solitary necrotic nodule (SNN) of the liver is an uncommon lesion, which is different from primary and metastatic liver cancers.

Objectives: To analyze the classification, CT and MR manifestation, and the pathological basis of solitary necrotic nodule of the liver (SNN) in order to evaluate CT and MRI as a diagnosing tool.

Patients and methods: This study included 29 patients with liver SNNs, out of which 14 had no clinical symptoms and were discovered by routine ultrasound examinations, six were found by computed tomography (CT) due to abdominal illness, four had ovarian tumors, and five had gastrointestinal cancer surgeries, previously. Histologically, these SNNs can be divided into three subtypes, i.e., type I, pure coagulation necrosis (14 cases); type II, coagulation necrosis mixed with liquefaction necrosis (five cases); and type III, multi-nodular fusion (10 cases). CT and magnetic resonance imaging (MRI) patterns were shown to be associated with SNN histology. All patients were treated surgically with good prognosis.

Results: CT AND MRI APPEARANCE AND CORRELATION WITH PATHOLOGY TYPES: three subtypes of lesions were hypo-density on both pre contrast and post contrast CT, 12 lesions were found the enhanced capsule and 1 lesion of multi- nodular fusion type showed septa enhancement. The lesions were hypo-intensity on T2WI and the lesions of type II showed as mixed hyperintensity on T2WI. The capsule showed delayed enhancement in all cases, and all lesions of multi- nodular fusion type showed delayed septa enhancement on MR images. 15 cases on CT were misdiagnosed and Four cases on MRI were misdiagnosed and the accuracy of CT and MRI were 48.3% and 86.2% respectively.

Conclusions: In conclusion, CT and MRI are useful tools for SNN diagnosis.

Keywords: Liver Neoplasms; Magnetic Resonance Imaging; Tomography, X-Ray Computed.

Figure 1. Pure Coagulation Necrosis Type of Solitary Necrotic Nodules (SNN) in a 45-Year-Old Woman (black arrow)

(A) Pre-contrast CT image of the right liver lobe; the SNN is a hypo-attenuated mass compared with the liver parenchyma. (B) Post-contrast CT image at the portal venous phase; the lesion shows no enhancement except for mild peripheral capsule enhancement. (C) By transverse T1WI, the SNN is hypo-intense relative to the liver parenchyma. (D) By transverse T2WI, the SNN is slightly hyper-intense relative to the liver parenchyma. (E) Contrast-enhanced T1WI at the portal venous phase; it shows no enhancement of the lesion except for moderate peripheral capsule enhancement. (F) Histology of the liver biopsy sample showed central necrotic tissue surrounded by a borderline zone containing infiltrating inflammatory cells and fibrotic changes. The outer layer shows normal hepatocytes (hematoxylin-eosin stained section, original magnification x100).

Figure 2. Coagulation Necrosis Mixed With a Liquefaction Necrosis Type of Solitary Necrotic Nodules (SNN) in a 50-Year-Old Man (GE Medical System) (black arrow)

(A) By transverse T1WI, the SNN is heterogeneous hypo-intensity relative to liver parenchyma at the right lobe of the liver. (B) By transverse T2WI, the SNN is slightly hyper-intense mixed with hyper-intense foci (white head arrow) relative to the liver parenchyma. Contrast-enhanced T1WI at arterial phase (C), at portal venous phase (D) and coronal contrast-enhanced T1WI at delay phase (E) shows no enhancement of the lesion except for marked peripheral capsule enhancement. (F) Histology of the SNN shows the liquefaction necrosis core surrounded by a coagulation necrosis area and infiltrating inflammatory cells (Hematoxylin-eosin stain; original magnification x100).

Figure 3. Multi-Nodular Fusion Type of Solitary Necrotic Nodules (SNN) (Black Arrow) in a 65-Year-Old Woman

A) On pre-contrast CT image, SNN is hyper-attenuating mass relatively to the background of fatty liver parenchyma. (B) By post-contrast CT imaging at the portal venous phase, the lesion shows no enhancement and an invisible peripheral capsule. On in phase (C) T1WI, the SNN is hypo-intensity relatively to liver parenchyma at the right lobe of the liver. (D) On T2WI, the SNN is isointense relative to liver parenchyma. (E) Contrast-enhanced T1WI at the delayed phase shows no enhancement of the lesion except at the septa and peripheral capsule enhancement. (F) Histology of the SNN shows multiple fusion nodules, and most lesions had coagulation necrosis surrounded by a fine fibrous capsule with infiltrating lymphocytes, plasma cells, and eosinophilic granulocytes (Hematoxylin-eosin stain; original magnification, x100).