Solitary necrotic nodule of the liver misinterpreted as malignant lesion: considerations on two cases

Contrast-Enhanced Ultrasound Findings in Patients with Rare Solitary Necrotic Nodule of the Liver - a Multicenter Report

PURPOSE

 This multicenter retrospective study highlights the contrast-enhanced ultrasound (CEUS) findings in a series of histologically proven solitary necrotic nodules (SNN) of the liver, a poorly understood pathologic entity of uncertain origin that mimics malignancy.

MATERIALS AND METHODS

 22 patients (M/F 13/9; mean age 59.4 years, SD ± 10.7, range 35-81) with histological diagnosis of SNN and CEUS were selected from clinical, imaging, and pathological archives of 7 US interventional centers, each of which provided 1 to 6 cases (mean 2.8). Pathological diagnosis was made on 20 US-guided biopsies and 2 surgical specimens. 2 patients had 2 SNNs with identical CEUS findings so that imaging analysis was carried out on 24 nodules.

RESULTS

 SNN was an incidental finding in healthy people in 10 cases (45.5 %), and it was discovered during follow-up for either known extrahepatic malignancies (9 cases = 41 %) or chronic liver disease (3 cases = 13.5 %). SNNs had a mean size of 19.3 mm (SD ± 6.5, range 9-40). On B-mode US, SNNs appeared hypoechoic in 14 cases (66.7 %), "target-like" in 7 cases (29.2 %), and homogeneously hyperechoic in 1 case (4.1 %). On CEUS, all lesions appeared devoid of contrast enhancement ("punched out" aspect) in the arterial, portal venous, and late phases after US contrast agent injection. A uniformly thin, hyperenhancing ring in the early arterial phase and isoenhanced with the surrounding parenchyma in the portal venous and late phases was found in 10 nodules (41.6 %). Clinical and imaging follow-up (mean duration 42.2 months, SD ± 34.9, range 2-108) was available in 15 patients with 16 SNNs: no changes in size and echostructure were seen.

CONCLUSION

 CEUS can contribute to the diagnosis of SNN when a "punched out" appearance in all vascular phases with or without thin rim enhancement in the very early arterial phase is present in healthy subjects in whom a focal liver lesion is incidentally found. In patients with a history of chronic liver disease or malignancy, US-guided biopsy represents the unavoidable first-line diagnostic modality.

Focal solitary necrotic nodules in fatty liver: characteristics on conventional and contrast-enhanced ultrasonography

PURPOSE

Focal lesions in fatty liver are difficult to diagnose using conventional ultrasonography (CVUS). The aim of this study was to investigate the characteristics of solitary necrotic nodules (SNNs) in fatty liver using CVUS and contrast-enhanced ultrasonography (CEUS) and to evaluate the diagnostic value of CEUS for SNNs in fatty liver.

METHODS

Fifteen SNNs in the fatty liver of fifteen patients were examined by both CVUS and CEUS. The contrast agent SonoVue was used for CEUS. The characterization and shape of these SNNs in the fatty liver were analyzed using CEUS.

RESULTS

CVUS revealed eight oval-shaped, six irregularly shaped, and one wedge-shaped SNN in the fatty liver. The six irregularly shaped lesions on CVUS were revealed to comprise four gourd-shaped, one serpiginous, and one 3-pin socket-shaped nodule on CEUS. One of these SNNs showed a subcapsular wedge shape, with peripheral and distinct internal septal hyperenhancement in the arterial phases that washed out in the portal phase; moreover, most areas of th lesion showed no internal enhancement in any of the three phases. Fourteen of the lesions were characterized as lacking internal enhancement, and 12 of them had mild-moderate peripheral thin enhancement in the arterial phases. Twelve of the 15 nodules could be considered for diagnosis as SNNs by CEUS, which was further proved by US-guided biopsy and histopathology. However none of them could be considered for diagnosis as SNNs by CVUS.

CONCLUSIONS

CEUS is a valuable tool for visualizing the characteristics of SNNs in fatty liver to improve the differential diagnosis.

A Challenging Case of Solitary Necrotic Nodules of the Liver Mimicking Hepatic Metastases: CT, MRI, and PET-CT Findings

Main teaching point: Solitary necrotic nodules of the liver can be multiple and usually appear as hypovascular nodules mimicking hepatic metastases, but they are relatively small and located in the subcapsular areas of the liver.

We report a very rare case of multiple solitary necrotic nodules of the liver mimicking hepatic metastases in a patient with previous history of lung cancer. The lesions appeared as low-attenuated or low-signal intensity nodules with thin rim enhancement on both contrast-enhanced computed tomography (CT) and magnetic resonance (MR) imaging, making them difficult to differentiate from hepatic metastases. This rare benign entity should be kept in mind, especially when lesions are small and located in the subcapsular areas of the liver.

Solitary necrotic nodule of the liver: a very challenging diagnosis!

Solitary necrotic nodule of the liver is a rare entity of unknown aetiology. We describe the case of a 59-year-old woman reporting sporadic right upper quadrant pain. An abdominal CT scan revealed a liver nodule located in segment 4. The complementary investigation was unable to identify the neoplastic lesion, and its surgical resection was performed, with an uneventful recovery. Pathological examination revealed a 'solitary necrotic nodule of the liver.' The patient remains asymptomatic and free of recurrence 3 years after surgery. This case corroborates that despite the advances in liver imaging and biopsy, liver nodules are sometimes a diagnostic challenge; quite often, only its surgical resection allows a definitive diagnosis.

The enigma of solitary necrotic nodule of the liver

BACKGROUND

Solitary necrotic nodule of the liver (SNNL) is a rare benign lesion with an uncertain aetiology. There are no typical diagnostic clinical or radiological features, and this lesion is usually detected incidentally during imaging for other purposes.

METHODS

We describe the clinical and radiological findings in three patients with histologically confirmed SNNL. The pertinent presenting features were documented and subsequent serological testing for parasites was performed.

RESULTS

All three patients underwent resection because it was not possible to exclude a solitary malignancy on preoperative imaging. All three nodules had a serpiginous shape with areas of necrosis that showed marked staining for eosinophil granules. However, no viable parasites were seen in any specimen. There were no specific radiological features that were present in all three patients. Two patients had travelled to areas where parasitic infections are endemic and one patient had an eosinophilia on presentation. The histopathological findings in conjunction with the clinical presentation suggest that SNNL may be parasitic in origin.

CONCLUSION

The diagnosis of SNNL is usually made after surgical excision. A preoperative diagnosis is difficult to make even with the use of multiple imaging modalities. The clinical and histopathological findings described in our three patients suggest that a transient parasitic infection is likely to be the cause in many cases. A history of potential exposure to parasites and serological testing for an eosinophilia or parasitic antibodies may help make the diagnosis of SNNL without the need for resection.

"Solitary" necrotic nodule of the liver: an enigmatic entity mimicking malignancy

AIM

The aim of the study is to further investigate the clinicopathological features of solitary necrotic nodules.

MATERIAL AND METHODS

Twenty-three archived cases of solitary necrotic nodule of the liver, which were preoperatively misdiagnosed as liver metastases were studied. The pathological findings were correlated with the clinical data of the patients.

RESULTS

The nodules were solitary in 20 cases and multiple (2) in three cases, and measured from 0.5-1.5 cm in diameter. Twenty-one cases were located in the right lobe of the liver (91.6%) and two in the left lobe (8.69%). Twenty nodules were found in the subcapsular region (86.95%), while three nodules were located within the hepatic parenchyma (13.04%). More then half of our cases (12) were accompanied by extended calcification. Granulomatous tissue resembling "burnt-out" parasitic granulomas was found in three cases.

CONCLUSIONS

Solitary necrotic nodules of the liver often mimic malignancy in abdominal imaging. Thus, permanent histopathology of the operative specimen remains the only accurate method of diagnosis. Their pathogenesis is most likely variable, and most reported cases are linked either to a parasitic or a vascular origin. Despite the designation of these lesions as "solitary" they may occasionally be multiple. In addition to the standard histological criteria of solitary necrotic nodules, the relatively small size (15 mm or less) and the frequent presence of calcifications seem to further characterize this enigmatic entity. Solitary necrotic nodule should be included in the differential diagnosis of small liver lesions with extensive necrosis.

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

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.

Solitary necrotic nodule of the liver: MR findings in 33 pathologically proved lesions

PURPOSE

To determine characteristic magnetic resonance (MR) imaging features of solitary necrotic nodule of the liver.

MATERIALS AND METHODS

MR images features of thirty-two patients (17 men, 15 women; mean age, 43 years; range, 24-76 years) with pathologically proved solitary necrotic nodule of the liver were retrospectively analyzed for number, size, signal intensity features and enhancement patterns.

RESULTS

A total of 33 lesions were identified. The mean diameter was 2.3cm (range 1.0-4.5cm). Thirty lesions (90.9%) were 1.0-3.0cm in diameter and only 3 lesions (9.1%) were larger than 3.0cm. On T1-weighted images, solitary necrotic nodule of the liver appeared hypointense in 31 lesions (93.9%) and isointense in 2 lesions (6.1%). On T2-weighted images, 12 (36.4%) lesions were hyperintense, 15 (45.4%) were isointense or invisible and 6 (18.2%) were hypointense. After injection of gadopentetate dimeglumine, all lesions were hypointense and none of them showed enhancement.

CONCLUSION

Solitary necrotic nodule of the liver is usually small with the size not exceed 3.0cm in diameter. Absence of enhancement on all dynamic phase after gadopentetate dimeglumine administration may be most characteristic feature of solitary necrotic nodule of the liver on MR images, which may help discriminate this entity from metastatic liver tumors and intrahepatic cholangiocarcinoma.

Solitary necrotic nodule of the liver: a report of two cases and review of the literature

To investigate the clinicopathological characteristics and possible causes of solitary necrotic nodule of the liver (SNN), two cases of SNN of the liver were studied with clinicopathological data, immunohistochemistry, and histochemistry staining. The patients had no specific symptoms, with negative results for the serum tumor markers. CT and ultrasound all showed low-density lesion. Morphologically, there was isolate, single necrosis tubercle of the liver. It was composed of a central necrotic core and a peripheral fibrotic capsule with inflammatory cells, including histiocytes, plasma cells, lymphocytes, and so forth. The staining result of PAS, acid-fast, and iron was all negative, and AG + VG staining showed that the outline of reticular fibers and collagen was intact. Vimtin was positive for necrotic tissue and surrounding fibrous tissue. CD34 and CD68 was both positive for case 1. CK was negative in case 2 but positive for a few residual cells in case 1. SNN of the liver is a rare nonmalignant disease with a good prognosis. Hemangioma and fatty liver might be ones of the causes of SNN.

Solitary necrotic nodule of the liver: always benign?

OBJECTIVE

Solitary necrotic nodule of the liver (SNNL) is a rare lesion and accepted as a benign entity. The aim of this study is to investigate the possible causes for the development of solitary necrotic nodules.

METHODS

Twenty-two retrospective solitary necrotic nodule specimens were examined to evaluate histologic features. The clinical records of these patients were reviewed, and clinical data were obtained for all patients.

RESULTS

Histologically, 17 of the 22 nodules were necrotic with surrounding fibrosis, and the remaining five nodules were completely fibrotic. Four of the 22 cases were found to have specific lesions within the nodules which may put light on the pathogenesis. Foci of metastatic carcinoma were identified in two of these four cases, and cuticle fragments of the hydatid cyst were identified in the other two cases. Clinical data showed that half of the cases with solitary necrotic nodule have an associated malignancy mainly involving the gastrointestinal system.

CONCLUSIONS

SNNL is not always benign. The possible causes of this lesion include parasites and metastatic tumors. It is important to identify the minute foci of metastatic carcinoma for the appropriate management of this lesion.

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.

Solitary necrotic nodule of the liver: different pathological findings express a different histogenesis

Solitary necrotic nodule of the liver is a rare benign lesion the histogenesis of which is still debated. We here report the case of a patient who underwent laparoscopic cholecystectomy for gallstones and who was accidentally found to have a solitary necrotic nodule of 2 cm in the fifth segment of the liver. On the basis of the histological findings, the hypothesis that different pathogenetic mechanisms could be involved in the histogenesis of this lesion is discussed.

Solitary necrotic nodule of the liver: contrast-enhanced sonography

PURPOSE

To report contrast-enhanced sonography (CEUS) for solitary necrotic nodule (SNN) of the liver and to assess its clinical value.

METHODS

CEUS was performed in 17 patients with pathologically proven SNN. Contrast pulse sequencing and the contrast agent SonoVue were used to depict lesion vascularity at a low mechanical index. The enhancement patterns were evaluated in real time.

RESULTS

Lesions were depicted as perfusion defects throughout all phases on CEUS.

CONCLUSIONS

CEUS can be a convenient imaging modality for the differential diagnosis of SNN and may obviate the need for further imaging studies.

Dynamic assessment of antiangiogenic therapy by monitoring both tumoral vascularization and tissue degeneration

Tumor growth is dependent both on endothelial and tumor cells. The aim of this study was to investigate dynamically whether changes in tumor vasculature implicate tumor tissue degeneration during antiangiogenic therapies. In order to quantify intra-tumor vascularization and necrosis, we have used ultrasound technology. This study has identified essential parameters needed to quantify specifically and sensitively the number of microvessels and the extent of necrosis in xenografted human carcinomas during natural tumor evolution, using contrast-enhanced high-frequency ultrasonography with (HFCDUS) or without (HFUS) color Doppler. We showed that quantification of intra-tumor microvessels between HFCDUS and immunohistochemistry is correlated using an anti-CD31 antibody. Furthermore, quantification of tumor necrosis with HFUS was confirmed by histological examination of hematoxylin-eosin-saffranin-stained sections over the observation period. Subsequently, for the assessment of novel angiogenic inhibitors, HFCDUS and HFUS were used to elucidate the underlying dynamics linking vessel inhibition and tumor eradication. We describe a novel application for HFCDUS/HFUS that constitutes an effective, convenient, and non-invasive method for clinical assessment of angiogenic inhibitors. In conclusion, we showed that tumor cells abruptly became necrotic following an antivascular therapy, whereas untreated tumors were protected from degeneration by a significant blood supply.

Rapid-growing solitary necrotic nodule of the liver

The solitary necrotic nodule of the liver is an uncommon nonmalignant lesion with an uncertain etiology. The lesion was defined as a nodule with a completely necrotic core and fibrous capsule etc. and without a consistency of viable cells. The characteristic features of this benign lesion on the imaging modalities are similar to the metastatic tumor. In this paper we discuss the case of a rapid-growing solitary necrotic nodule of the liver occurring in a patient with chronic renal failure on hemodialysis. The lesion located on the left median lobe of the liver had rapidly enlarged in diameter in the last seven months. Despite some examinations by imaging modalities to confirm the preoperative diagnosis, we were unable to visually confirm. Several histological examinations using a needle biopsy specimen were performed, but the diagnosis was all necrotic tissue. However, we recommended an extended left hepatic lobectomy for this rapid-growing lesion since cholangiocarcinoma with necrosis could be hardly differentiated. Permanent histology revealed that the lesion was solitary necrotic nodule. We consider that permanent histology of the entire lesion is possibly the only accurate method of diagnosis. Since the solitary necrotic nodule does not indicate malignancy, hepatic resection should be performed.

Solitary necrotic nodule of the liver: a riddle that is difficult to answer

Solitary necrotic nodule of the liver is an unusual lesion that is often an incidental finding on abdominal imaging, intraoperative examination, or post mortem. Most reported cases of solitary necrotic nodule have been in males, and over three quarters of these lesions have occurred in the right lobe of the liver. Pathologically, solitary necrotic nodule is a benign lesion characterized by a completely necrotic core that is often partly calcified, surrounded by a dense hyalinized fibrous capsule containing elastin fibres. The ultrasound appearance of solitary necrotic nodule is usually of a "target" lesion with a hyperechoic center, while on CT scan they appear as non-enhancing hypodense lesions that are typical of metastatic adenocarcinoma or peripheral cholangiocarcinoma. The impression of malignancy is further enforced with the finding of necrotic cellular material on biopsy and the macroscopically hard and "gritty" nature of the nodules. Currently, permanent histopathology of solitary necrotic nodules is the only accurate method of diagnosis. However, solitary necrotic nodules are usually of a bilobed or lobulated shape that is unusual for malignant liver lesions, and they often lie in close proximity to hepatic inflow structures. Solitary necrotic nodule should be suspected in liver lesions with this configuration, location, and on a biopsy showing a large amount of necrosis.