Acute focal bacterial nephritis or renal abscess? A sonographic diagnosis

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

BACKGROUND

Acute focal bacterial nephritis (AFBN) is a rare disease currently described only in case reports and small case series. In this study we summarize the clinical features of AFBN as has been documented in the literature and draw recommendations on the proper diagnosis and therapy.

METHODS

A systematic literature review was undertaken in PUBMED, Web of Science and The Cochrane Library online databases for relevant literature on AFBN in adults.

RESULTS

Literature review revealed a total of 38 articles according to our inclusion criteria, of which we could extract data from 138 cases of AFBN. Fever (98%) and flank pain (80%) were most commonly reported symptoms. E. coli was the most frequent pathogen. Diagnosis was set by CT and/or MRI (52%) with or without sonography or by sonography alone (20%) as well as by sonography combined with IVU. In total, sonography was applied in 83% of cases. All but one patient received antibiotic treatment. Kidney lesions were occasionally mistaken for neoplasms or renal abscesses and as a result, cases were subjected to percutaneous puncture (12.3%), surgical exploration (5.1%) and partial or radical nephrectomy (4.4%). Four cases (2.9%) developed a renal abscess.

CONCLUSIONS

The diagnosis of AFBN is set by characteristic clinico-radiological findings. Differential diagnoses of this interstitial bacterial infection include renal abscess and tumor. Correct diagnosis is occasionally impeded by atypical symptoms. Invasive diagnostic and therapeutic procedures should be limited as the majority of cases respond well to conservative treatment.

Focal bacterial nephritis (lobar nephronia) presenting as renal mass

A focal infection of the kidney can cause a diagnostic dilemma by mimicking a neoplasm. We describe a case of focal bacterial nephritis (acute lobar nephronia) caused by Escherichia coli in which the diagnosis was confirmed only after surgical exploration. Although the patient had fever on admission, urine and blood cultures were negative and fine needle aspiration of the kidney could not rule out a well-differentiated carcinoma.

Acute focal bacterial nephritis

Clinical and radiographic characteristics of 12 patients with acute focal bacterial nephritis (AFBN) are presented along with review of the literature. Most patients presented with symptoms of an inflammatory or infectious process. Fever and pyuria were the most frequently encountered clinical characteristics. Imaging modalities that were used to establish a definitive diagnosis of focal bacterial nephritis included ultrasound, computed tomography, and intravenous urography with nephrotomography. Ultrasound was found to be the most effective and least costly method of diagnosis. Misdiagnosis of AFBN as abscess or tumor, which it may stimulate, could lead to inappropriate surgical therapy.

Perinephric and intrarenal abscesses

Perinephric and intrarenal abscesses remain a significant source of morbidity and mortality as well as a diagnostic dilemma. The history, epidemiology, disease classification, etiology, diagnosis, and treatment are reviewed, with special attention to new diagnostic and treatment modalities.

Acute focal bacterial nephritis

In the kidney, acute focal parenchymal infection without liquefaction can produce a 'mass lesion' that may mimic an abscess or tumour, both clinically and radiologically. Ultrasound and computed tomography can differentiate between these lesions and allow appropriate antibiotic treatment to be used safely, avoiding unnecessary surgical intervention.