title: MR imaging of focal medullary sponge kidney: case report.
abstract: We present a case of focal medullary sponge kidney (MSK) that mimicked a renal tumor. Evaluation of a patient with history of macrohematuria revealed a left renal mass of 3-cm diameter. T(1)-weighted magnetic resonance (MR) images revealed a mass of mixed intensity protruding toward the renal sinus. On fat-saturated T(2)-weighted MR images, the lesion's remarkable hyperintensity suggested the presence of an aggregation of tiny cysts. On diffusion-weighted MR images, the mass also demonstrated high intensity, and its apparent diffusion coefficient was partly decreased (1.12 × 10(-3) mm(2)/s). On computed tomography, precontrast images revealed no calcification in the mass. Although slight enhancement was seen in the corticomedullary phase, thick and dense streaks of contrast radiating peripherally were identified in the mass in the excretory phase. Focal MSK was diagnosed. We discuss the potential of MR imaging for diagnosing focal MSK.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hida
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nishie
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Asayama
authors.forename: Kousei
authors.initials: K
authors.lastname: Ishigami
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Fujita
authors.forename: Junichi
authors.initials: J
authors.lastname: Inokuchi
authors.forename: Seiji
authors.initials: S
authors.lastname: Naito
authors.forename: Sadamu
authors.initials: S
authors.lastname: Ando
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D006801:Humans; D007668:Kidney / Q000473:pathology*; D007680:Kidney Neoplasms / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D007691:Medullary Sponge Kidney / Q000473:pathology*