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Diagnosis: Lobar Nephronia

Acute lobar nephronia (ALN), also termed as acute focal nephritis or acute focal bacterial nephritis, is a non-liquefactive localized severe infection of the interstitium of the parenchyma of the kidney involving one or more of the renal lobes (Masood Y, et al. Acute Lobar Nephronia in an infant presented as a renal tumor. Urol Case Rep. 2020;34:101450. [PubMed link]). It is considered a midpoint in the spectrum of upper urinary tract infection between acute pyelonephritis and intrarenal abscess (Ruhela A, Madison G. Acute lobar nephronia: a condition more common in children, a road less travelled in the adults. MOJ Clin Med Case Rep. 2018;8:77-80. [Full text link]).

The term ALN was coined by John Hodson in the year 1974 when he described acute pyelonephritis restricted to one segment of the kidney secondary to intrarenal reflux in the presence of infected urine. The term was used in analogy to acute lobar pneumonia. The first case of ALN was described by Rosenfield et al. in 1979. It is also called as acute focal pyelonephritis. There is disagreement in the literature regarding the nomenclature used to describe ALN. Some clinicians and radiologists use the term “complicated pyelonephritis” which likely accounts for ALN being under diagnosed. Rathore et al in their case series and review of acute lobar nephronia suggest that ALN is a better term to distinguish it from general bacterial infections of the kidney (Rathore MH, et al. Acute lobar nephronia: a review. Pediatrics. 1991;87:728-34 [PubMed link]) Escherichia coli is the most common causative organism of ALN, however, many other microorganisms may be the causative agent.

ALN can be confused with neoplastic lesions, which could lead to unnecessary surgical procedures.

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