Inflammatory pseudotumor in the Spiegel lobe of the liver of an elderly woman

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.

Inflammatory Myofibroblastic Tumor of the Liver: A Diagnostic Challenge

Inflammatory myofibroblastic tumor (IMT) is an uncommon myofibroblastic neoplasm that was formerly included within the broad category of inflammatory pseudotumor (IPT). IMT is rarely encountered in the liver. Similar to IMT of other organs, the interchangeable use of the terms IMT and IPT in liver has made the analysis of these lesions difficult. In this review, clinical and pathological features of IMT of the liver are reviewed and the differential diagnosis of IMT is discussed, with emphasis on IPT and the other entities included in this large category. IMT can mimic malignant tumors. There are no known unique diagnostic clinical, laboratory, or radiological features. The definitive diagnosis of IMT depends on careful pathological examination. The histopathological evaluation of hepatic IMT reveals that, the myxoid/vascular pattern is the most frequently observed, followed by, in decreasing frequency, fibrous histiocytoma-like pattern and hypocellular fibrous pattern. In IMT of the liver, anaplastic lymphoma kinase (ALK) expression reliably predicts the presence of an ALK gene rearrangement. The diagnosis of hepatic IMT depends on the dominant histopathological pattern, and the management of the disease is still controversial. IMT of the liver is a distinctive neoplasm of intermediate biological potential, and should be distinguished from the variety of lesions that are included under the broad category of IPT. Therefore, to avoid confusion regarding the true incidence and behavior of hepatic IMT, the term IPT should not be used interchangeably with IMT. The rarity of IMT in liver should not minimize its consideration in the differential diagnosis of liver tumors, especially in patients with tumor markers in normal range.

Advancement of research on inflammatory myofibroblastic tumor of the liver

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm composed of transformed myofibroblastic spindle cells with infiltration of a large number of inflammatory cells and/or lymphocytes. The etiology of IMT remains unknown. IMT occurs at various sites and often affects young adults and children. IMT of the liver mostly arises in the right lobe of liver. Biopsy, computed tomography (CT) and magnetic resonance imaging (MRI) are beneficial to diagnosis and differential diagnosis. Vimentin, smooth muscle actin (SMA), muscle-specific actin (MSA) are often positive by immunohistochemistry. The prognosis of most patients is favorable after surgery. In this article, we reviewed the overseas and domestic literatures and summarized the advancement of research on the IMT of the liver about etiology, pathogenesis, clinical presentations, imaging feature, histological appearance, immunohistochemical and electron microscopic feature, diagnosis, differential diagnosis and therapy.

Inflammatory pseudotumor of the liver masquerading as hepatocellular carcinoma after a hepatitis B virus infection: Report of a case

We report a rare case of hepatic inflammatory pseudotumor (IPT) after a hepatitis B virus (HBV) infection. Early contrast enhancement on computed tomography (CT) with a washout phenomenon at the delayed phase, and depleted Kupffer cell function on superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) suggested hepatocellular carcinoma (HCC). However, the lack of a tumor capsule, absence of liver cirrhosis, and normal serum levels of alpha-fetoprotein and PIVKA-II (protein induced by vitamin K absence; descarboxyprothrombin) contradicted this diagnosis. We excised the tumor to exclude malignancy, and the histopathological diagnosis was IPT. Recent evidence suggests that this entity has changed from an extremely rare pathology to an established disease. Thus, IPT should be considered in the differential diagnosis of a liver mass with an infectious-inflammatory antecedent. Although surgery is not mandatory, surgical removal is recommended if there is a possibility of malignancy. Further investigations are warranted to elucidate the mechanisms of IPT developing after an HBV infection.