Acute Focal Bacterial Nephritis or Renal Abscess? A Sonographic Diagnosis

Abstract

The radiological and sonographic findings of acute focal bacterial nephritis in 3 patients are presented. The sonographic appearance of a poorly marginated mass in the renal cortex, with echo amplitude less than the normal parenchyma and with poor transmission, should suggest the diagnosis of acute focal bacterial nephritis in a patient with pyrexia and a tender renal mass. These features of poor echogenicity and lack of posterior enhancement contrast with the presence of patchy echogenicity and posterior enhancement found in the renal abscess. This is of surgical importance, as the management may tend to be conservative in the one and surgical in the other.

Acute focal bacterial nephritis is associated with invasive diagnostic procedures - a cohort of 138 cases extracted through a systematic review

“…Immune compromising diseases as well as other predisposing factors are associated with the formation of AFBN according to our cohort, such as Diabetes mellitus [1, 8, 9, 13–18], pregnancy [4, 14, 19], urinary tract abnormalities [1, 3, 4, 8–10, 14, 20, 21], prior or concurrent respiratory tract infection [3, 4, 16], former kidney transplantation [7, 22–24], alcohol and drug abuse [2, 25, 26], autoimmune diseases [1, 6, 10] and AIDS [25] (Table 2). Yet it has to be emphasized that AFBN also affects previously healthy immunocompetent patients.…”

“…Aspirates showed no drainable pus but grew Pseudomonas aeruginosa [23] and MRSA [30] respectively and adaptation of antibiotic therapy led to a favorable disease course for both patients. Two patients (1.5%) required ureteral stenting or stone extraction due to underlying obstructive lithiasis [4, 16] and three patients (2.2%) underwent nephrectomy because of reported non-response to antibiotic therapy or rather therapeutic mismanagement [1]. In addition to the above-named interventions further invasive procedures were applied in a significant number of cases due to uncertainty in diagnosis of AFBN, most commonly suspicion for a renal malignancy or abscess.…”

Two Cases of Acute Focal Bacterial Nephritis

“…AFBN is common in pediatrics and is considered to be associated with urinary malformation or VUR. Imaging findings for AFBN are characteristic; ultrasonography reveals nephromegaly [3], whereas contrastenhanced CT reveals oval and wedge-shaped masses with obscure borders and poor contrast enhancement in the arterial phase [4]. However, CT findings sometimes require exclusive diagnosis from liver abscesses and/or malignant renal tumors.…”

Acute Focal Bacterial Nephritis and Renal Abscess Associated with Vesicoureteral Reflux

“…Sonographically, a renal abscess is detected as a hypoechoic lesion with enhanced through transmission [6,9], Several reports have described the sonographic ap pearance of AFBN [6,9,10], In the majority of cases, the involved segment of the kidney was hypoechoic with poorly defined margins, absence of corticomedullary definition, and without through transmission. But in some cases it was hyperechoic or normal [6,10].…”