A case of IgG4-related hepatic inflammatory pseudotumor replaced by an abscess after steroid treatment

Hepatic pseudotumor: A diagnostic challenge

Hepatic pseudotumors are rare lesions of unknown origin, characterized by the proliferation of fibrous connective tissue and inflammatory cell infiltrates. They mimic malignant lesions clinically, and radiologically, given their non-specific clinical and imaging features. The pathophysiology of hepatic pseudotumor is incompletely understood and there are no standardized criteria for diagnosis. Pseudotumors have been reported to develop in various organs in the body with the lung and liver being the most common site. Hepatic pseudotumors develop in patients with underlying triggers of liver inflammation and injury, including infections, autoimmune liver diseases, bile duct injury, or surgery. Hepatic pseudotumors respond well to conservative treatment with antibiotics, and steroids and some may regress spontaneously, thus avoiding unnecessary resection. This condition is rewarding to treat. It is important to recognize pseudotumor as a distinct clinical entity and include it in the differential of liver masses with atypical imaging features.

A case report of IgG4-related hepatic inflammatory pseudotumor in a 3-year old boy

Background

Hepatic Inflammatory Pseudotumor (IPT) is an infrequent condition often masquerading as a malignant tumor, resulting in misdiagnosis and unnecessary surgical resection. The emerging concept of IgG4-related diseases (IgG4-RD) has gained widespread recognition, encompassing entities like IgG4-related hepatic IPT. Clinically and radiologically, corticosteroids and immunosuppressive therapies have proven effective in managing this condition.

Case Presentation

A 3-year-old Chinese boy presented to the clinic with an 11-month history of anemia, fever of unknown origin, and a tender hepatic mass. Blood examinations revealed chronic anemia (Hb: 6.4 g/L, MCV: 68.6 fl, MCH: 19.5 pg, reticulocytes: 1.7%) accompanied by an inflammatory reaction and an elevated serum IgG4 level (1542.2 mg/L). Abdominal contrast-enhanced computed tomography unveiled a 7.6 cm low-density mass in the right lateral lobe, while magnetic resonance imaging demonstrated slight hypointensity on T1-weighted images and slight hyperintensity on T2-weighted images, prompting suspicion of hepatic malignancy. A subsequent liver biopsy revealed a mass characterized by fibrous stroma and dense lymphoplasmacytic infiltration. Immunohistochemical analysis confirmed the presence of IgG4-positive plasma cells, leading to the diagnosis of IgG4-related hepatic IPT. Swift resolution occurred upon initiation of corticosteroid and mycophenolate mofetil therapies.

Conclusion

This study underscores the diagnostic approach to hepatic IPT, utilizing histopathology, immunostaining, imaging, serology, organ involvement, and therapeutic response. Early histological examination plays a pivotal role in clinical guidance, averting misdiagnosis as a liver tumor and unnecessary surgical interventions.

Incidental Finding of Hepatic Inflammatory Pseudotumor Immunoglobulin G4-Related Disease With Underlying Chronic Hepatitis C

Immunoglobulin G4-related disease (IgG4-RD) is a unique immunological disease that can impact multiple organs including a formation of a hepatic inflammatory pseudotumor (IPT). We present a case of a 67-year-old male with a history of chronic viral hepatitis C infection who had an accidental finding on magnetic resonance imaging (MRI) of a liver arterially enhancing lesion. With an extensive work-up, immunohistochemical stains for immunoglobulin G of the liver lesion was performed and showed markedly increased IgG4-positive plasma cells (> 50/HPF), which was consistent with hepatic inflammatory pseudotumor related to IgG4-RD. The patient was treated with prednisone with a complete resolution of the hepatic lesion. The diagnosis of hepatic IPT and IgG4-RD requires a high degree of clinical suspicion and coordination with a multi-disciplinary team, including pathologists. Early tissue acquisition and staining for IgG4 was essential for the early diagnosis and treatment in this case. We also provide a comprehensive summary of published reports of IgG4-RD presenting with IPT.

IgG4-Related Hepatic Pseudotumor Masquerading as a Klatskin Tumor

Immunoglobulin G subclass 4 (IgG-4)-related disease (IgG4-RD) is an uncommon immune-mediated, fibro-inflammatory disease which has garnered recognition as a systemic condition. One manifestation of the disease in the hepatobiliary system is the development of hepatic inflammatory pseudotumors. These benign tumors are often misdiagnosed as malignant tumors and undergo unnecessary hepatic resections. We present a case of IgG4-related hepatic inflammatory pseudotumor (IPT) mimicking a Klatskin tumor. A high degree of clinical suspicion and extensive workup is imperative in reaching the correct diagnosis. IgG4-related inflammatory pseudotumor is a rare entity, but an important consideration in evaluating hepatic tumors.

Magnetic resonance imaging of inflammatory pseudotumor of the liver: a 2021 systematic literature update and series presentation

PURPOSE

Inflammatory pseudotumors of the liver (IPTL) are not exceptional benign lesions with various etiologies, histology, and imaging appearances. The incomplete knowledge of this pathology and the wide polymorphism sometimes resembling malignancy often induce long and expensive diagnostic flow, biopsy and occasionally unnecessary surgery. We propose a systematic revision of MRI literature data (2000-2021) with some narrative inserts and 10 new complete MRI cases, with the aim of organizing the data about IPTL and identifying some typical features able to improve its diagnosis from imaging.

METHODS

We performed a systematic revision of literature from 2000 to 2021 to obtain MRI features, epidemiological, and clinical data of IPTL. The basic online search algorithm on the PubMed database was "(pseudotumor) AND (liver) AND (imaging)." Quality assessment was performed using both scales by Moola for case report studies and by Munn for cross-sectional studies reporting prevalence data. A case-based retrospective study by collecting patients diagnosed with IPTL from three different university hospitals from 2015 to 2021 was done as well. Only cases with MR examinations complete with T1/T2/contrast-enhanced T1/Diffusion-Weighted (W) images and pathology-proven IPTL were selected.

RESULTS

After screening/selection 38 articles were included for a total of 114 patients. In our experience we selected 10 cases for a total of 16 IPTLs; 8 out of 10 patients underwent at least 1 MRI follow-up. Some reproducible and rather typical imaging findings for IPTL were found. The targetoid aspect of IPTL is very frequent in our experience (75% on T1W, 44% on T2W, 81% on contrast-enhanced T1W (at least one phase), 100% on Diffusion-W images) but is also recurrent in the literature (6% on T1W, 31% on T2W, 51% on CE-T1W (at least one phase), 18% on Diffusion-W images, and 67% on hepatobiliary phase). In our experience, Apparent Diffusion Coefficient map values were always equal to or higher than those of the surrounding parenchyma, and at MRI follow-up, nodule/s disappeared at first/second control, in six patients, while in the remaining 2, lesions persisted with tendency to dehydration.

CONCLUSION

A targetoid-like aspect of a focal liver lesion must raise diagnostic suspicion, especially if IgG4-positive plasma is detected. MRI follow-up mainly shows the disappearance of the lesion or its reduction with dehydration.

Fevers, Sweats, Weight Loss, Oh My! When IgG4 Related Disease Comes Knocking. .

Immunoglobulin G4-related systemic disease (IgG4-RSD) is a fibro-inflammatory immune condition characterized by IgG4 positive plasma cells, fibrosis, and frequently elevated serum IgG4 level. Akin to sarcoidosis, IgG4-RSD is a systemic disease with diverse organ manifestations linked by common histopathologic features. IgG4-RSD typically presents sub acutely without significant constitutional symptoms or fever. Hepatic Inflammatory pseudotumor (HIP) is a rare manifestation of IgG4-RSD composed of dense lymphoplasmacytic infiltrate and extensive fibrosis. We present an older Asian male who presented with acute onset of fever and weight loss found to have IgG4-RSD complicated by a HIP and concomitant MSSA abscess.

IgG4-related hepatic inflammatory pseudotumor mimicking cholangiolocellular carcinoma

Inflammatory pseudotumor (IPT) is a benign tumor mass composed of chronic infiltration of inflammatory cells and fibrous tissue. IgG4-RD (related disease) in the hepatobiliary system has been widely recognized and includes IgG4-related hepatic IPT. This report describes a patient with IgG4-related hepatic IPT with sclerosing cholangitis. A 75-year-old woman was admitted to our hospital for the treatment of rectal cancer. Abdominal contrast-enhanced computed tomography revealed a low-density mass, 2.5 cm in diameter, in the left lateral lobe. Magnetic resonance imaging showed that the mass was slightly hypointense on T1-weighted images and slightly hyperintense on T2-weighted images. Based on these results, we made a diagnosis of cholangiolocellular carcinoma, and we performed a left hepatectomy. Histopathological examination showed that the mass was composed of fibrous stroma with dense lymphoplasmacytic infiltration. Immunohistochemically, IgG4-positive plasma cells were observed. The final diagnosis was IgG4-related hepatic IPT with sclerosing cholangitis. IgG4-related IPT is a relatively rare disease that can occur in any organ of the body. Although the accurate diagnosis of IgG4-related hepatic IPT remains difficult, IgG4-RD should be included in the differential diagnosis of liver tumors and histological analysis performed.

Intratumor Abscess in a Posttraumatic Hepatic Inflammatory Pseudotumor Spreading Out of the Liver

A 45-year-old woman with abdominal pain after minor trauma was referred to our hospital. Computed tomography (CT) showed a hypovascular tumor in the left liver lobe. A tumor biopsy revealed granuloma, although no findings indicated malignancy or infection. A follow-up imaging study showed spread of the hepatic tumor. Her abdominal pain worsened after a second minor trauma. CT revealed an intratumor abscess, and pus overflowed from the patient's umbilicus. The abscess was improved by antibiotics and drainage therapy. In this case, unusual imaging findings and an atypical disease course of a hepatic inflammatory pseudotumor were observed.

Difficulty in differentiating between IgG4-related hepatic inflammatory pseudotumor and intrahepatic cholangiocarcinoma

A 71-year-old man on prednisolone for immunoglobulin (Ig) G4-related renal disease showed increased carbohydrate antigen (CA) 19–9 level; abdominal enhanced computed tomography (CT) showed a lesion in the left lateral segment and dilatation of the peripheral biliary duct. He was referred to our hospital for detailed examination for suspected intrahepatic cholangiocarcinoma. CT and magnetic resonance imaging findings were similar to those for intrahepatic cholangiocarcinoma. However, endoscopic retrograde cholangiopancreatography showed a smooth narrowing of the bile duct which suggested inflammatory disease. Liver biopsy was performed; IgG4-related hepatic inflammatory pseudotumor (IPT) was diagnosed. IgG4-related hepatic IPTs are rare diseases that develop in association with the development of sclerosing cholangitis. Most of these lesions develop in the hepatic hilum and the imaging findings of these tumors are similar to those of hilar cholangiocarcinomas. Thus, hepatic IPTs are difficult to differentiate from malignancy; in some cases, surgical resection has been considered for establishing the diagnosis. In the present case, we could diagnose hepatic IPT on the basis of liver biopsy, which is the recommended approach in cases of suspected hepatic IPT.

An Enigmatic Liver Mass in a Child

Hepatic space occupying lesions in childhood are a diagnostic challenge, as they are caused by a variety of malignant and nonmalignant disorders with a different prognosis and, of course, treatment. They are often misdiagnosed or diagnosed only after surgical resection. A 14-year-old boy presented with abdominal pain, evening-rise fever with loss of appetite and weight. The patient also developed jaundice after 2 months of above symptoms. Ultrasound of the abdomen showed an irregular infiltrative mass in segment IV of the liver. Gadobenate disodium magnetic resonance imaging done showed T1 hypointense and T2 hyperintense lesions in segment VIII of the liver with extension into porta with delayed enhancement suggestive of fibrous tumor. Liver biopsy showed extensive liver parenchymal fibrosis with a mixed inflammatory infiltrate with eosinophils. Bacterial, tubercular, and fungal culture of liver biopsy were negative. Although serum IgG4 levels were 7.88 g/L (N =1.9 g/L), IgG4 staining of liver biopsy was negative. The patient was started on prednisolone 1 mg/kg considering the diagnosis of inflammatory pseudotumor (IPT). Twenty days after starting the steroid, mass lesions were converted into multicystic abscess requiring antibiotics and pigtail drainage. On follow-up, patient had improved symptoms with mass lesions turned into small-sized abscess cavity. Hepatic IPTs are difficult to differentiate from malignant tumors, as they are rare and can have variable imaging findings. To avoid inadvertent surgery, histological confirmation of the hepatic mass is essential. Steroids should be used with caution with close follow-up to prevent iatrogenic complications, such as a chronic liver abscess.

Steroid Therapy and Steroid Response in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP), a unique subtype of pancreatitis, is often accompanied by systemic inflammatory disorders. AIP is classified into two distinct subtypes on the basis of the histological subtype: immunoglobulin G4 (IgG4)-related lymphoplasmacytic sclerosing pancreatitis (type 1) and idiopathic duct-centric pancreatitis (type 2). Type 1 AIP is often accompanied by systemic lesions, biliary strictures, hepatic inflammatory pseudotumors, interstitial pneumonia and nephritis, dacryoadenitis, and sialadenitis. Type 2 AIP is associated with inflammatory bowel diseases in approximately 30% of cases. Standard therapy for AIP is oral corticosteroid administration. Steroid treatment is generally indicated for symptomatic cases and is exceptionally applied for cases with diagnostic difficulty (diagnostic steroid trial) after a negative workup for malignancy. More than 90% of patients respond to steroid treatment within 1 month, and most within 2 weeks. The steroid response can be confirmed on clinical images (computed tomography, ultrasonography, endoscopic ultrasonography, magnetic resonance imaging, and 18F-fluorodeoxyglucose-positron emission tomography). Hence, the steroid response is included as an optional diagnostic item of AIP. Steroid treatment results in normalization of serological markers, including IgG4. Short- and long-term corticosteroid treatment may induce adverse events, including chronic glycometabolism, obesity, an immunocompromised status against infection, cataracts, glaucoma, osteoporosis, and myopathy. AIP is common in old age and is often associated with diabetes mellitus (33-78%). Thus, there is an argument for corticosteroid therapy in diabetes patients with no symptoms. With low-dose steroid treatment or treatment withdrawal, there is a high incidence of AIP recurrence (24-52%). Therefore, there is a need for long-term steroid maintenance therapy and/or steroid-sparing agents (immunomodulators and rituximab). Corticosteroids play a critical role in the diagnosis and treatment of AIP.

[Hepatopancreaticobiliary diseases in IgG4-associated autoimmune diseases]

BACKGROUND

IgG4-related diseases are rare systemic multiorgan diseases and can thus affect any organ system. The incidence of diagnosis has significantly increased due to increasing awareness.

OBJECTIVE

In the abdomen the hepatopancreaticobiliary system provides an essential organ system for the expression of IgG4-associated autoimmune diseases. The focus here is autoimmune pancreatitis type 1 but IgG4-associated sclerosing cholangitis and IgG4-associated hepatopathy, which can also occur in combination are less well-known.

METHODS

Various mostly Asiatic, histologically-based diagnostic systems, such as HISORt or international consensus diagnostic criteria (ICDC) are available for the diagnostics of hepatopancreaticobiliary IgG4-related autoimmune diseases, in which imaging techniques playing an increasingly important role.

RESULTS

In addition to generalized organ swelling further morphological and also functional imaging criteria have become increasingly well-known for autoimmune pancreatitis, such as late enhancement or the imaging response to steroid therapy. Magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERP) can provide valuable information for the diagnostics of IgG4-related diseases in the hepatopancreaticobiliary system.

CONCLUSION

IgG4-related autoimmune diseases of the hepatopancreaticobiliary system are a rare group of diseases in which increasing knowledge of the radiological appearance also leads to an increasingly frequency of diagnosis. IgG4-related diseases must be distinguished from non-necrotizing pancreatitis and pancreatic cancer, which is often difficult but has significant therapeutic consequences for the patients.

A Case of Type 1 Autoimmune Pancreatitis (AIP), a Form of IgG4-Related Disease (IgG4-RD)

BACKGROUND Type 1 autoimmune pancreatitis (AIP), also known as lymphoplasmacytic sclerosing pancreatitis (LPSP), is a rare cause of chronic pancreatitis, characterized by a fibro-inflammatory process. However, patients with AIP may have a good response to corticosteroid therapy. We describe a Tunisian patient with AIP that was confirmed to be an IgG4-related disease (IgG4-RD). CASE REPORT We describe a case of a 70-year-old man who was admitted to hospital for obstructive jaundice and abdominal pain. Serum liver function tests were abnormal and upper abdominal computed tomography (CT) imaging showed diffuse pancreatic swelling and strictures of the main pancreatic duct without any focal lesion. Pancreatico-biliary magnetic resonance imaging (MRI) showed a thickened rim surrounding the pancreatic duct Serum IgG4 levels were elevated, resulting in a diagnosis of IgG4-related AIP. The patient showed a good clinical, biochemical, and radiological response following steroid therapy in combination with azathioprine. CONCLUSIONS The diagnostic workup of IgG4-RD is complex and usually requires a combination of clinical examination, imaging, and serological analysis. As this case report has demonstrated, IgG4-RD should be considered in patients who present with pancreatitis or AIP, because of the favorable response to steroid therapy, particularly when treatment is initiated early.