[Spurious renal tumor: acute lobar nephronia].

OBJECTIVE: To report a case of acute lobar nephronia, an unusual form of localized renal infection, and review the literature with special reference to the clinical features, ultrasound and CT findings that distinguish this condition from other renal masses (abscess, infected cyst and renal carcinoma).

METHODS/RESULTS: A female patient presented at the emergency services with symptoms and signs compatible with pyelonephritis. An admission abdominal ultrasound scan demonstrated a solid mass in the left inferior renal pole. CT showed a renal mass with peripheral enhancement after infusion of contrast and central striation. Blood and urine analyses were compatible with renal infection. Acute lobar nephronia was suspected and antibiotic treatment was administered. Control ultrasound and CT examinations performed one month after instituting antibiotic treatment showed the mass had disappeared.

CONCLUSIONS: Acute lobar nephronia should be considered in all patients with a renal mass detected during an episode of urinary infection. Correlation of the clinical and radiological findings, and resolution of the mass with appropriate antibiotic therapy will confirm the diagnosis.