Inflammatory Pseudotumor of the Ulnar Nerve Mimicking a Malignant Peripheral Nerve Sheath Tumor: A Radiologic Puzzle.

Inflammatory pseudotumor (IPT) of a peripheral nerve is a rare non-neoplastic tumefactive inflammatory condition, often mimicking malignancy. The etiology of this condition is still unknown. Clinically and radiologically, the lesion can mimic a malignant tumor. This case report represents, as far as we know, the first publication describing the ultrasonography findings and the results of advanced dynamic contrast-enhanced magnetic resonance imaging (MRI) and diffusion-weighted MRI of IPT in a peripheral nerve. Suspicion of this entity on imaging can speed up the definitive diagnosis and potentially avoid overly radical treatment.

Intradural-extramedullary inflammatory pseudotumour of the cervical spinal cord of a dog.

An 8-year-old mixed-breed dog was presented with cervical hyperesthesia, tetraparesis, and mild proprioceptive ataxia in all four limbs. 3 Tesla MRI showed a dorsal compressive intradural-extramedullary mass at the level of C1-C2, isointense to the gray matter with a hypointense ventral core on T2 weighted images (WI), isointense on T1WI, with a strong and homogeneous contrast enhancement. A C1-C2 partial dorsal laminectomy was performed, and the lesion was removed en bloc. The histopathological and immunohistochemical analysis defined the diagnosis of inflammatory pseudotumor.

Inflammatory myofibroblastic tumor of the lung involving the central nervous system in pediatric patients.

INTRODUCTION: The inflammatory myofibroblastic tumor (IMT) is a very rare lesion with an incidence of less than 0.1% of total neoplasms and with main affection in the lungs. Involvement in the central nervous system is extremely rare, but with a much more aggressive course than IMT diagnosed in the rest of the body. We report the 2 cases presented in our neurosurgery department to date; both were treated satisfactorily without intercurrences in 10 years of follow-up. HISTORICAL BACKGROUND: The World Health Organization described the IMT as a distinctive lesion composed of myofibroblastic spindle cells accompanied by an inflammatory infiltrate of plasma cells, lymphocytes, and eosinophils. CLINICAL PRESENTATION: Clinical manifestations of patients with CNS IMT vary and may consist of headache, vomiting, seizures, and blindness. Seizures are the most common symptom in patients with focal lesions. DIAGNOSIS: The true origin of this entity remains to be elucidated, but to date, etiologies ranging from chromosomal alterations to autoimmune or postinfectious mechanisms have been described. Due to its rarity and non-specificity in imaging, the final diagnosis of IMT in the brain parenchyma relies on pathological examination. MANAGEMENT: Treatment options are controversial and include total or subtotal removal, high-dose steroids, and radiation therapy. In the last decade, the development of ALK Tyrosine Kinase Inhibitors allows the possibility of chemotherapy in those patients harboring ALK mutations. CONCLUSION: IMT is a rare tumor that can exceptionally be found in the CNS. The cause is still unknown although the different studies focus on a neoplastic origin. The diagnosis is based in the use of different modalities of imaging and with histological confirmation. Optimal management is gross total resection whenever possible, is the only established curative treatment. Further research with longer follow-up is needed to clarify the natural history of this rare tumor.

IgG4-negative pituitary inflammatory pseudotumor with sphenoidal involvement resembling a macroadenoma.

BACKGROUND: Inflammatory pseudotumors (IPTs) are rare benign conditions of unknown etiology that can affect any part of the body. IPTs are most commonly associated with Immunoglobulin G4 (IgG4)-related disease. Central nervous system IPTs, especially with pituitary involvement, are even rarer entities. The presence of an IgG4-negative pituitary IPT with simultaneous extracranial involvement has not been reported. CASE REPORT: We present the case of a 41-year-old female with past medical history of rheumatoid arthritis and a diagnosis of pituitary IPT with coexisting sphenoidal (extracranial) involvement mimicking a pituitary macroadenoma at presentation. The patient underwent multiple consecutive biopsies, and an extensive workup prior to establishing the diagnosis. Laboratory work-up showed normal serum IgG4 and unremarkable liver function tests. CONCLUSION: Pituitary lesions with simultaneous sphenoidal involvement in patients with IgG4-negative systemic inflammatory disease should raise the clinical suspicion for intracranial IPTs, as these tumors can mimic aggressive counterparts causing adjacent bony erosion, and local invasion.

[Hepatic Inflammatory Pseudotumor Mimicking Cholangiocarcinoma: A Rare Case and Literature Review]. / Pseudotumor inflamatorio hepático: caso clínico y revisión de la literatura.

We report the case of a 49-year-old man who attended the emergency department for a two-month history of compromised general condition, weight loss, abdominal pain, fever, and elevated inflammatory parameters. An imaging study demonstrates a bulky liver tumor associated with dilation of the bile duct and retroperitoneal adenopathies (hepatic hilum, intermediate, and right lumbar groups). These findings raise intrahepatic cholangiocarcinoma within the differential diagnoses, reason why segmental hepatectomy and regional lymphadenectomy were performed. Histopathology and immunochemistry revealed a lymphoplasmacytic inflammatory process with IgG4-positive plasma cells compatible with IgG4-associated disease. After the resection, expectant management was decided, with the patient evolving favorably, asymptomatic, and without signs of recurrence. We present a case and a brief literature review of an hepatic inflammatory pseudotumor, a rare entity with a benign behavior.

Inflammatory Pseudotumour Of The Urachus: Case Report And Literature Review.

A 52 year old woman presented to the emergency department of Affiliated Hospital of Zunyi Medical University, Zunyi, China in May 2022, complaining of a palpable lower abdominal mass since two days. She denied haematuria, umbilical drainage, or any other urinary symptoms. Previous health record indicated that the patient was diagnosed with urachal inflammatory pseudotumour. Inflammatory pseudotumourous masses of the urachal canal are rare chronic inflammatory disorders with only a few case reports. Ultrasonography is the preferred method for diagnosing urachal lesions. Contrast- enhanced ultrasonography (CEUS) allows real-time visualization of the microvascular blood flow within the solid lesion, reducing the probability of misdiagnosis of the disease. We have reported a case of urachal inflammatory pseudotumour and analyzed its ultrasonographic findings from two-dimensional conventional ultrasonography and CEUS to provide support for the diagnosis of urachal inflammatory pseudotumour in the clinic and to assist clinical selection of effective treatment modalities.

Imaging features and radiologic-pathologic correlations of inflammatory pseudotumor-like follicular dendritic cell sarcoma.

BACKGROUND: Inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) is a rare tumor. This study aimed to reveal the radiological characteristics of IPT-like FDCS by radiologic-pathologic correlation. RESULTS: We analyzed two cases of IPT-like FDCS in the liver, nine in the spleen, and two in both the liver and spleen concomitantly. IPT-like FDCS presented as well-defined iso- or hypodense masses on unenhanced computed tomography (CT) images in both the liver and spleen. Hyperintensities on T1-weighted images and hypointensities on T2-weighted images with hypointense rings were characteristic features in splenic cases. "Halo signs" were observed in two out of three liver tumors. Hepatic lesions showed significant enhancement, whereas splenic lesions showed only mild enhancement. Delayed annular enhancement was observed in both liver and spleen cases. On ultrasonographic examination, IPT-like FDCS presented as hypoechoic lesions with enhancement similar to that observed on CT. Hyaline fibrous pseudocapsules, which correlated with the hypointensities on T2-weighted images, were microscopically observed at the tumor edge. IPT-like FDCS was characterized by an abundance of small blood vessels and capillaries. Capillaries were also found in the fibrous capsule of some IPT-like FDCSs, which may explain the delayed annular enhancement. CONCLUSIONS: The manifestations of IPT-like FDCS in the liver and spleen showed differences that warrant them to be approached differently during diagnosis. Characteristic radiological findings of IPT-like FDCS included different enhancement patterns between liver and spleen tumors and rim-like hypointensities on T2-weighted images, as well as annular enhancement on CT and magnetic resonance images. These imaging features correlated with tumor pathology.

DCTN1-ALK gene fusion in inflammatory myofibroblastic tumor (IMT) of the CNS.

PURPOSE: Inflammatory myofibroblastic tumor (IMT) is a rare neoplastic tumor type of intermediate biological potential, only recently distinguished from the non-neoplastic category of inflammatory pseudotumor (IP). The literature describes very few cases of IMTs arising in the central nervous system (CNS), and the distinguishing clinical, pathological, and molecular features of IMT-CNS are not well understood. Our purpose is to publish a case of an IMT-CNS with a novel DCTN1-ALK gene fusion, furthering in the literature's characterization of a rare tumor type. METHODS: Review of the literature included a PubMed Database search of articles found by the following searches: "Inflammatory myofibroblastic tumor;" "Inflammatory myofibroblastic tumor central nervous system;" "ALK gene fusion;" and "DCTN1-ALK gene fusion." Inclusion of articles discovered by these search terms was determined through critical appraisal of article relevance, number of citations, cross-citation within articles of interest, and rare findings with conflicting conclusions in an effort to reduce publication bias. RESULTS: We present a case of IMT-CNS with several distinctive molecular features including a DCTN1-ALK gene fusion, the first of its kind described in an intracranial IMT. CONCLUSION: IMT is an infrequent tumor type and its presentation within the CNS is exceedingly rare. The paucity of cases, along with the ambiguity of terminology in the literature, has stunted accurate clinical, pathological, and molecular characterization of IMT-CNS. Our case report improves the characterization of the recently appreciated category of IMT-CNS so that connections between phenotype and prognosis, and between genotype and treatment, can eventually be made.

Inflammatory myofibroblastic tumour of an unusual presentation in the uterine cervix: a case report.

BACKGROUND: Inflammatory myofibroblastic tumour is an infrequent mesenchymal neoplasia of unknown aetiology and variable behaviour, ranging from rather benign lesions to locally aggressive and even metastatic disease. Its presence has been described in almost all organs; however, its location in the female genital tract has rarely been reported. CASE PRESENTATION: We present the case of a 47-year-old female, who was studied in our institution for a recent medical history of several weeks of dyspareunia and abdominal pain. She underwent pertinent studies including ultrasonography and CT scan. Under suspicion of degenerated leiomyoma, a total hysterectomy was performed. Unexpectedly, the pathological study of the surgical specimen showed very few tumour cells with focal fusiform morphology surrounded by an abundant inflammatory infiltrate; a thorough immunohistochemistry study lead to myofibroblastic tumour of the cervix diagnosis. A PET-CT scan did not show metastatic disease. The patient did not undergo any adjuvant treatment, and she is currently on surveillance with no evidence of disease relapse. CONCLUSIONS: Inflammatory myofibroblastic tumour remains a rare entity yet to be fully elucidated. The diagnosis is based on pathological study due to the lack of typical clinical manifestations and typical radiological images. Surgical resection is the most frequent treatment, whereas chemotherapy and radiotherapy are restricted to locally advanced or metastatic disease. Tirosine kinase inhibitor crizotinib has shown promising results especially in tumours harbouring ALK mutation.

Inflammatory pseudotumor-like follicular dendritic cell sarcoma of the liver.

A 53-year-old female with a history of HLA-B27 positive polyarthritis underwent a splenectomy due to an incidental splenic lesion, which was confirmed as an inflammatory pseudotumor (IPT). Afterwards, two liver lesions were found and histopathological examination revealed inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS). The patient received NSAIDs, corticosteroids, antibiotics and azathioprine, with no response. Within the next few months, there was an abrupt clinical worsening due to rapid progression of the hepatic lesions and a massive hepatomegaly. New biopsies were obtained, showing undifferentiated sarcoma. The patient started chemotherapy with doxorubicin and eventually died.

Inflammatory myofibroblastic tumour of genitourinary system.

Two cases of inflammatory myofibroblastic tumour (IMT) involving the genitourinary system are presented. One patient with mass of urinary bladder came in with lower abdominal pain whereas the second patient complained of right flank pain and investigations showed a mass involving the right kidney. At present, no specific guidelines exist for the management of inflammatory myofibroblastic tumours. In this case report, we will discuss the work-up and the management stratégies adopted for each case.

[Clinicopathological features of inflammatory myofibroblastic tumor].

Objective: To investigate the clinicopathological diagnosis and differential diagnosis of inflammatory myofibroblastic tumor (IMT). Methods: Thirty-two cases of IMT collected at the People's Hospital of Jiangsu Province from May 2010 to May 2020 were evaluated for their clinical, histologic, immunohistochemical and genomic features, and relevant literature was reviewed. Results: There were 19 male and 13 female patients, with age ranging from 5 to 65 years (mean, 37 years). The tumors were located in the lung and mediastinum (10 cases), gastrointestinal tract and mesentery/omentum (12 cases), urinary bladder (5 cases), head and neck (3 cases), somatic soft tissue (1 case), and retroperitoneum (1 case). Four cases of epithelioid inflammatory myofibroblastic sarcoma (EIMS) were all located intra-abdominally. Histologically, the tumor cells were myofibroblasts and fibroblasts arranged in predominantly fusiform pattern, with variably edematous to myxoid background or sclerotic collagenized stroma, and variably mixed chronic or acute inflammatory cells infiltration. EIMS were composed mainly of epithelioid tumor cells, with myxoid stroma and numerous neutrophils. Immunohistochemically, the tumor cells expressed cytoplasmic ALK (25/32, 78%), whereas the four EIMS showed nuclear membrane ALK staining pattern. The tumor cells also expressed CKpan (8/19), SMA (24/32, 75%) and desmin (12/32, 38%); all four EIMS also showed strong positivity for desmin. Fluorescence in situ hybridization (FISH) for ALK gene rearrangement showed split apart signals in 12 of 15 cases, most commonly with atypical signals. Next-generation sequencing (NGS) was performed in three tumors and showed that one case of lower leg IMT harbored a novel CLIP2-ALK fusion, and two cases of EIMS harbored RANBP2-ALK fusion. Follow-up data were available in 29 patients. Twenty-two patients were alive with no evidence of tumor, four patients had tumor recurrences (three patients were treated with crizotinib and were alive with tumor), and three patients died of the disease (including two patients with EIMS). Conclusions: IMTs show a wide morphologic spectrum, and should be differentiated form a variety of benign or malignant tumors. Immunohistochemistry (ALKp80, ALKD5F3) and FISH (ALK break-apart probe) could assist the diagnosis of IMT, with NGS recommended for the atypical cases.

Lorlatinib for the treatment of inflammatory myofibroblastic tumour with TPM4-ALK fusion following failure of entrectinib.

Inflammatory myofibroblastic tumour (IMT) is a rare malignancy with limited responses to corticosteroids and chemotherapy. About half of cases have activating rearrangements in the ALK gene which could be targeted with ALK inhibitors. A 40-year-old man presented with a large right lung mass and nodal, trapezius and cerebral metastases. Biopsy confirmed IMT with TPM4-ALK fusion. He was treated with prednisolone without clinical benefit. He received the Trk/ROS1/ALK inhibitor entrectinib in a clinical trial but his disease progressed in less than 3 months. Ifosfamide and etoposide in addition to radiotherapy to the brain and chest were administered. Transient improvement in the radiotherapy-treated areas was observed but his disease progressed shortly afterwards on all sites including the development of new adrenal metastasis. Compassionate use of the third-generation ALK inhibitor lorlatinib resulted in excellent partial response on all disease sites after 2 months, followed by a further 6 months of disease stabilisation. Repeat imaging showed slight increase in size of the cerebral metastasis but stable disease elsewhere, for which he was given stereotactic radiotherapy. His disease progressed 3 months later and lorlatinib was substituted with another ALK inhibitor brigatinib but he deteriorated and died shortly afterwards. Our patient tolerated lorlatinib well for 11 months with minimal toxicities, although he developed unilateral right-sided lung consolidation that was probably related to a combination of infection, radiotherapy and lorlatinib, which needed treatment with antibiotics and corticosteroids. This case demonstrates a role of lorlatinib in the treatment of TPM4-ALK-rearranged IMT despite failure of entrectinib.

A case of inflammatory pseudotumour of the gallbladder presenting as a big mass of uncertain behavior.

BACKGROUND: Inflammatory pseudotumour has been used to describe an inflammatory or fibrosing tumoral process of an undetermined cause that may involve a variety of organ systems, including the lungs, spleen, liver, lymph nodes, pancreas and extrahepatic bile duct with potential for recurrence and persistent local growth. In this article, we report a patient with a big mass of uncertain nature and behavior. CASE PRESENTATION: A 60-year-old woman presented with a 1-week history of abdominal pain, fever and jaundice. Six months before she had had right upper quadrant pain that was interpreted as biliary colic. A contrast-enhanced CT scan showed a big mass of soft tissue with diffuse infiltration of the gallbladder, displacement of the transverse colon, hepatic flexure and duodenum. For diagnostic distinction between a chronic inflammatory disease or a neoplasm, exploratory laparotomy was required. Intraoperative exploration disclosed a big mass of hard texture involving the gallbladder, with multiple concrements, hepatoduodenal ligament, right and transverse mesocolon, stomach and duodenum. Cholecystectomy was performed, preserving adjacent organs with macroscopic desmoplastic reaction. Histopathologic examination of the gallbladder showed a spindle cell proliferation with diffuse chronic inflammatory infiltrate of lymphocytes, plasma cells and hyalinized fibrous stroma. No vascular invasion or cellular atypia were evident. CONCLUSION: Inflammatory pseudotumour is a rare condition and diagnostic distinction from a chronic inflammatory disease or other neoplasm is only possible by histopathologic examination. There is a limited number of case reports in the literature indicating tumor location in the gallbladder.

Cross-segment spinal plasma cell granuloma:a case report.

BACKGROUND: Plasma cell granuloma (PCG) is a rare non-neoplastic entity, with the precise etiology remaining unclear. Vertebra-affected spinal PCG has not been reported yet. This report presented a case with cross-segment spinal PCG in thoracolumbar region. CASE PRESENTATION: A 32-year-old male patient presented to the authors' hospital since his health check-up results showed osteolytic lesions in the thoracolumbar spine. He felt asymptomatic throughout the course. Radiological examination revealed destructive changes at T12 and L1 vertebrae. Whereas laboratory examination excluded malignant tumor. The results of routine incisional biopsy remained inconclusive, thereby necessitating complete excision of the lesions. Finally, the infiltration of plasma cells observed by pathological examination of the surgical specimen confirmed the diagnosis of PCG. CONCLUSIONS: To the authors' knowledge, this was the first case of cross-segment spinal PCG with osteolytic property. The possibility of PCG should be considered for the diagnosis and differential diagnosis of an osteolytic lesion in the spine. Since the etiology of PCG is unknown, the disorder was confirmed based on excluded diagnosis. Surgical resection is recommended both for the definite diagnosis and treatment of spinal PCG.

[Inflammatory myofibroblastic tumor of the lung: histopathology and imaging findings]. / Akcigerin inflamatuvar miyofibroblastik tümörü: histopatoloji ve görüntüleme bulgulari.

Inflammatory myofibroblastic tumor is a neoplasia of unknown clinical etiology that clinically and radiologically tends to mimic a malignant neoplasm. The tumor is histologically composed of a mixture of inflammatory cells, myofibroblastic spindle cells and plasma cells. It can occur in any part of the body. Although pulmonary inflammatory myofibroblastic tumor is the most common primary lung mass especially in childhood, this entity is usually not considered in differential diagnosis of lung nodules or masses. In this article, we aimed to disscus the pathology and imaging findings of the pulmonary inflammatory myofibroblastic tumor and increase the familiarity of radiologists and clinicians to this entity.

Imaging and pathological findings of intramedullary inflammatory pseudotumour in a miniature dachshund: a case report.

BACKGROUND: Inflammatory pseudotumours (IPTs) are distinctive lesions consisting of myofibroblastic spindle cells and a variety of inflammatory cells. The aetiology of IPTs is unknown. Reports of IPTs in veterinary medicine have been scarse. Moreover, only one case of intradural extramedullary IPT has been previously reported. In this report, we introduce the first known case of canine IPT, which occurred in the parenchyma of the spinal cord. CASE PRESENTATION: A 10-year-old female Miniature Dachshund presented with a 2-month-long history of progressively worsening ataxia and tetraparesis. Neurological examination was consistent with a lesion involving the cervical spinal cord. Magnetic resonance imaging revealed an intradural space-occupying lesion in the region of the fourth cervical vertebra. Dorsal laminectomy and resection of the mass were performed. Histopathological examination revealed the proliferation of immature spindle cells (fibroblasts/myofibroblasts and glial cells) and a highly cellular mixture of neutrophils, macrophages and lymphocytic cells. The mass was located in the parenchyma of the spinal cord and was diagnosed as an IPT occurring in the parenchyma of the spinal cord. No causative pathogen was detected. The dog's symptoms improved, during the first month after surgery. However, neurological symptoms, such as laboured breathing and dysuria, subsequently worsened and the dog died 42 days after surgery. CONCLUSIONS: The present study describes a canine case of IPT occurring in the parenchyma of the spinal cord. The diagnosis and determination of the site of the mass was difficult solely based on preoperative imaging in the present case. The outcome of this case was poorer than that observed in cases of canine extramedullary IPT and human intramedullary IPT, in which the patients exhibited recovery. The prognosis after surgical resection cannot be decided from the present case alone. However, patients should be monitored for potential serious complications and recurrence.

Spectral Computed Tomography Imaging in the Differential Diagnosis of Lung Cancer and Inflammatory Myofibroblastic Tumor.

OBJECTIVE: The aim of this study was to explore the value of spectral computed tomography (CT) imaging in differentiating lung cancer from inflammatory myofibroblastic tumor (IMT). METHODS: One hundred twelve patients with 96 lung cancers and 16 IMTs underwent spectral CT during arterial phase (AP) and venous phase (VP). The normalized iodine concentration in AP (NICAP) and VP (NICVP), slope of spectral Hounsfield unit curve in AP (λAP) and VP (λVP), and normalized iodine concentration difference between AP and VP (ICD) were calculated. The 2-sample t test compared quantitative parameters. Two readers qualitatively assessed lesion types according to imaging features. Receiver operating characteristic curves were generated to calculate sensitivity and specificity. Sensitivity and specificity of the qualitative and quantitative studies were compared. RESULTS: The patients with IMT had significantly higher NICAP, NICVP, λAP, λVP, and ICD than did the patients with lung cancer (P < 0.05). The threshold NICVP of 0.425 would yield the highest sensitivity and specificity of 92.7% and 81.3%, respectively, for differentiating lung cancer from IMT. The logistic regression model produced from combining quantitative parameters NICAP, NICVP, λAP, and λVP provided a sensitivity and specificity of 100% and 81.3%, respectively, for differentiating lung cancer from IMT. CONCLUSIONS: Spectral CT imaging with the quantitative analysis may help to increase the accuracy of differentiating lung cancer from IMT.

Dynamic contrast-enhanced MRI in orbital lymphoproliferative disorders: Effects of region of interest selection methods on time efficiency, measurement reproducibility, and diagnostic ability.

BACKGROUND: Previous studies indicated that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) could serve as a useful biomarker for differentiating malignant from benign orbital lymphoproliferative disorders (OLPDs). PURPOSE: To investigate the influence of different region of interest (ROI) selection methods on the measurements of DCE-MRI parameters, and their diagnostic ability in discriminating malignant from benign OLPDs. STUDY TYPE: Retrospective study. POPULATION: In all, 46 patients with OLPDs (22 benign and 24 malignant). FIELD STRENGTH/SEQUENCE: 3.T DCE-MRI using a 2D turbo fast low angle shot sequence postcontrast. ASSESSMENT: DCE-MRI data were analyzed using three different ROI selection methods, including whole-tumor ROI (ROIWT ), single-slice ROI (ROISS ) and hot-spot ROI (ROIHS ). Quantitative parameters (Ktrans , Kep , Ve ) were calculated based on a modified Tofts model. STATISTICAL TESTING: Analysis of variance test, intraclass correlation coefficient (ICC), Bland-Altman plots, independent t-test, and receiver operating characteristic curve analyses were used for statistical analyses. RESULTS: The time required for outlining ROIWT was significantly longer than ROISS and ROIHS (P < 0.001). The measurements of DCE-MRI-derived parameters based on ROIHS demonstrated lowest ICC, followed by ROISS and ROIWT . Malignant OLPDs showed significantly higher Kep than benign mimics (P < 0.001), while no significant differences were found on Ktrans (ROIWT , P = 0.535; ROISS , P = 0.557; ROIHS , P = 0.400) and Ve (ROIWT , P = 0.071; ROISS , P = 0.079; ROIHS , P = 0.057). Kep -ROIWT showed the highest area under curve for differentiating malignant from benign OLPDs, followed by Kep -ROISS , and Kep-ROIHS ; however, the differences were not significant (ROIWT vs. ROISS , P = 0.407; ROIWT vs. ROIHS , P = 0.363; ROISS vs. ROIHS , P = 0.887). DATA CONCLUSION: ROI selection methods could have an influence on the measurements of DCE-MRI parameters. Taking measurement time, reproducibility, and diagnostic ability into account, we suggest single-slice ROI to be used for differentiating malignant from benign OLPDs in clinical practice. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1298-1305.

Inflammatory Pseudotumor-Like Follicular Dendritic Cell Sarcoma of the Spleen: Computed Tomography Imaging Characteristics in 5 Patients.

OBJECTIVES: The purpose of this study was to retrospectively review the computed tomography (CT) and clinicopathological characteristics of inflammatory pseudotumor (IPT)-like follicular dendritic cell sarcoma (FDCS) of the spleen in 5 patients. METHODS: Clinical, pathologic, and CT imaging findings of 5 patients with IPT-like FDCS of the spleen were reviewed and analyzed. Computed tomography imaging and pathologic features were compared. RESULTS: Abdominal unenhanced CT revealed a well-defined hypodense mass in the spleen with complex internal architecture with focal necrosis and/or speckle-strip calcification. On postcontrast CT, slightly delayed enhancement was observed in 5 cases. Four patients had a normalized spleen. The fourth patient had lung metastasis. The fifth patient had 2 relatively small lesions as well as metastases to the spine. CONCLUSIONS: Computed tomography imaging features of IPT-like FDCS of the spleen are distinctly different from other hypovascular splenic neoplasm; however, the definitive diagnosis requires further confirmation with needle biopsy or surgery. Inflammatory pseudotumor-like FDCS of the spleen should be suggested by using the CT imaging features of the splenic mass with evidence of metastatic disease.