Multimodality imaging of renal lymphoma and its mimics

Computed Tomographic Characteristics of Feline Renal Cell Carcinoma and Renal Lymphoma: A Comparative Analysis

This retrospective, multicenter study aimed to identify key computed tomography (CT) features that differentiate renal cell carcinoma (RCC) from lymphoma, the two most common feline renal neoplasms. CT images from 25 cats with renal tumors (15 RCC and 10 lymphoma) were evaluated. Of the RCC cases, 10 were diagnosed through histopathology and 5 through FNA. Among the lymphoma cases, two were extranodal lymphoma, including one case of primary renal lymphoma, and eight were gastrointestinal (GI) lymphoma with renal involvement. Qualitative features (tumor distribution, growth pattern, and enhancement characteristics) and quantitative parameters (tumor size and attenuation values) from triphasic or single post-contrast-enhanced CT scans were analyzed and compared. RCC typically presented as unilateral (93.3%) masses with expansile growth (73.3%) and heterogeneous enhancement among contrast-enhancing tumors (100%). Lymphoma more often showed bilateral involvement (60%), infiltrative growth (50%), and homogeneous enhancement (90%) (p < 0.001). Tumor vessel enhancement was observed exclusively in RCC. Compared with lymphoma, RCC demonstrated significantly higher attenuation values in the late nephrographic/early excretory phase. While histopathology remains the gold standard, this study provides a detailed CT analysis of these tumors, specifically within a feline population.

Is fat quantification based on proton density fat fraction useful for differentiating renal tumor types?

PURPOSE

This study retrospectively assessed the diagnostic accuracy of fat quantification based on proton density fat fraction (PDFF) for differentiating renal tumors.

METHODS

In this retrospective study, 98 histologically confirmed clear cell renal cell carcinomas (ccRCCs), 35 papillary renal cell carcinomas (pRCCs), 14 renal oncocytomas, 16 chromophobe renal cell carcinomas (chRCCs), 10 lymphomas, 19 uroepithelial tumors, 10 lipid-poor angiomyolipomas (AMLs), and 25 lipid-rich AMLs were identified in 226 patients (127 males and 99 females) over 5 years. All patients underwent multiparametric kidney MRI. The MRI protocol included an axial plane and a volumetric 3D fat fraction sequence known as mDIXON-Quant for PDFF measurement. Demographic data were recorded, and PDFF values were independently reviewed by two radiologists blinded to pathologic results. MRI examinations were performed using a 1.5 T system. MRI-PDFF measurements were obtained from the solid parts of all renal tumors. Fat quantification was performed using a standard region of interest for each tumor, compared to histopathological diagnoses. Sensitivity and specificity analyses were performed to calculate the diagnostic accuracy for each histopathological tumor type. Nonparametric variables were compared among the subgroups using the Kruskal-Wallis H test and Mann Whitney U test. P-values < 0.05 were considered statistically significant.

RESULTS

In all, 102 patients underwent partial nephrectomy, 70 patients underwent radical nephrectomy, and the remaining 54 had biopsies. Patient age (mean: 58.11 years; range: 18-87 years) and tumor size (mean: 29.5 mm; range: 14-147 mm) did not significantly differ across groups. All measurements exhibited good interobserver agreement. The mean ccRCC MRI-PDFF was 12.6 ± 5.06% (range: 11.58-13.61%), the mean pRCC MRI-PDFF was 2.72 ± 2.42% (range: 2.12-3.32%), and the mean chRCC MRI-PDFF was 1.8 ± 1.4% (range: 1.09-2.5%). Clear cell RCCs presented a significantly higher fat ratio than other RCC types, uroepithelial tumors, lymphomas, and lipid-poor AMLs (p < 0.05). Lipid-rich AMLs demonstrated a very high fat ratio.

CONCLUSION

MRI-PDFF facilitated accurate differentiation of ccRCCs from other renal tumors with high sensitivity and specificity.

Urologic Imaging of Collecting System and Ureters: Cancers and Mimics

Urothelial carcinoma can arise from any portion of the urothelial lining extending from the kidneys to the urethra, with morphologic subtypes including papillary, polypoid, infiltrative, and ulcerative growth patterns. Imaging plays a crucial role in detecting upper and lower urinary tract tumors and in differentiating them from other benign mimics. Computed tomographic urography (CTU) is the imaging modality of choice for the diagnosis of urothelial carcinoma as well as for noninvasive surveillance following treatment. CTU allows evaluation of recurrent primary tumor while evaluating for metastatic disease in a single study.

Predominantly multiple focal non-cystic renal lesions: an imaging approach

Multiple non-cystic renal lesions are occasionally discovered during imaging for various reasons and poses a diagnostic challenge to the practicing radiologist. These lesions may appear as a primary or dominant imaging finding or may be an additional abnormality in the setting of multiorgan involvement. Awareness of the imaging appearance of the various entities presenting as renal lesions integrated with associated extrarenal imaging findings along with clinical information is crucial for a proper diagnostic approach and patient work-up. This review summarizes the most relevant causes of infectious, inflammatory, vascular, and neoplastic disorders presenting as predominantly multiple focal non-cystic lesions.

Left ovarian mass revealing multivisceral lymphoma

Lymphoma encompasses a range of cancers originating in the lymphatic system, categorized into Hodgkin lymphoma and non-Hodgkin lymphoma. Hodgkin lymphoma classically present as nodal disease, whereas non-Hodgkin lymphoma tends to involve extranodal regions. While it can be part of a systemic lymphoma, isolated nodal involvement is not uncommon. Extranodal lymphoma can affect virtually any organ or tissue, with the spleen, liver, gastrointestinal tract, pancreas, abdominal wall, genitourinary tract, adrenal glands, peritoneal cavity, and biliary tract being among the most commonly involved sites, in decreasing order of frequency. We present a case involving a 54-year-old woman presented with left iliac fossa pain. A sonography was performed, which showed left pelvic mass, magnetic resonance imaging showed left ovarian mass with enlargement of the cervix. Computed tomography revealed enlargement of the pancreas and adrenal glands, along with masses in the kidneys associated with extensive pathological lymph node enlargement in the para-aortic and pelvic regions. The patient underwent biopsy of a para-aortic lymph node, which revealed a diffuse large B cell lymphoma.

Unusual presentation in a case of diffuse large B-cell lymphoma

Non-Hodgkin's lymphoma are neoplasms derived from T cells and B cells and their precursors in the lymphoid system with higher susceptibility in involvement of extra-nodal sites. Predominant ureteric involvement is an unusual presentation. We present a case of diffuse large B-cell lymphoma with secondary involvement of ureter who had symptoms of urinary tract infection in absence of positive urine culture, non-responsive to broad spectrum antibiotics and masquerading pyogenic infection leading to pyelonephritis with ureteritis. Radiological examination revealed mass like soft tissue thickening of ureter extending from renal pelvis throughout the length of ureter. FNAC as well as biopsy from the periureteric thickening revealed lymphomatous involvement of ureter. The following case report provides insight on differentials and varied symptoms of lymphomatous involvement of ureter.

Multiple and hereditary renal tumors: a review for radiologists

80% of renal carcinomas (RC) are diagnosed incidentally by imaging. 2-4% of "sporadic" multifocality and 5-8% of hereditary syndromes are accepted, probably with underestimation. Multifocality, young age, familiar history, syndromic data, and certain histologies lead to suspicion of hereditary syndrome. Each tumor must be studied individually, with a multidisciplinary evaluation of the patient. Nephron-sparing therapeutic strategies and a radioprotective diagnostic approach are recommended. Relevant data for the radiologist in major RC hereditary syndromes are presented: von-Hippel-Lindau, Chromosome-3 translocation, BRCA-associated protein-1 mutation, RC associated with succinate dehydrogenase deficiency, PTEN, hereditary papillary RC, Papillary thyroid cancer- Papillary RC, Hereditary leiomyomatosis and RC, Birt-Hogg-Dubé, Tuberous sclerosis complex, Lynch, Xp11.2 translocation/TFE3 fusion, Sickle cell trait, DICER1 mutation, Hereditary hyperparathyroidism and jaw tumor, as well as the main syndromes of Wilms tumor predisposition. The concept of "non-hereditary" familial RC and other malignant and benign entities that can present as multiple renal lesions are discussed.

Typical and Atypical Imaging Features of Malignant Lymphoma in the Abdomen and Mimicking Diseases

Malignant lymphoma typically presents with homogeneous enhancement of enlarged lymph nodes without internal necrotic or cystic changes on multiphasic CT, which can be suspected without invasive diagnostic methods. However, some subtypes of malignant lymphoma show atypical imaging features, which makes diagnosis challenging for radiologists. Moreover, there are several lymphoma-mimicking diseases in current clinical practice, including leukemia, viral infections in immunocompromised patients, and primary or metastatic cancer. The ability of diagnostic processes to distinguish malignant lymphoma from mimicking diseases is necessary to establish effective management strategies for initial radiological examinations. Therefore, this study aimed to discuss the typical and atypical imaging features of malignant lymphoma as well as mimicking diseases and discuss important diagnostic clues that can help narrow down the differential diagnosis.

The Role of CT Imaging in Characterization of Small Renal Masses

Small renal masses (SRM) are increasingly detected incidentally during imaging. They vary widely in histology and aggressiveness, and include benign renal tumors and renal cell carcinomas that can be either indolent or aggressive. Imaging plays a key role in the characterization of these small renal masses. While a confident diagnosis can be made in many cases, some renal masses are indeterminate at imaging and can present as diagnostic dilemmas for both the radiologists and the referring clinicians. This review focuses on CT characterization of small renal masses, perhaps helping us understand small renal masses. The following aspects were considered for the review: (a) assessing the presence of fat, (b) assessing the enhancement, (c) differentiating renal tumor subtype, and (d) identifying valuable CT signs.