Prolonged dural enhancement by iodine contrast agent mimicking subdural haematoma in a patient with nephrogenic systemic fibrosis

Abstract

A 65-year-old woman with end-stage renal disease was hospitalized with diabetic gangrene in 2009. Magnetic resonance angiography using intravenous gadodiamide was performed at the time of femoral–popliteal artery bypass operation in 2007. Skin induration of the extremities and articular contractures of the fingers and knees were severe. Skin biopsy demonstrated marked fibrocellular thickening without inflammatory cell invasion of the corium or hypodermal tissue. A diagnosis of CD34 was positive. Collagen disease was negative based on clinical and serological findings. The diagnosis of nephrogenic systemic fibrosis (NSF) is made by a combination of clinical, laboratory and histopathologic findings. Non-contrast head CT was performed on the day after coronary and lower extremity angiography with iodine contrast media because of chronic headache. The head CT scan demonstrated a subdural high-density area (HDA; Figure 1). We first diagnosed atraumatic acute subdural haematoma, but the wavy border on the convolution side of the HDA suggested subdural thickening. After 1 week, head CT without contrast media demonstrated that the HDA had disappeared and the same area showed a slightly higher density area than the cerebrospinal fluid (Figure 2). These thickened dura were hypointense on axial T1-weighted magnetic resonance images. We diagnosed dural thickening rather than subdural haematoma on CT imaging. Dural NSF involvement has been infrequently described [1–3]; furthermore, an imaging report by Zelasko et al. is the only case described to date [2]. Dural thickening is generally differentiated. However, an accidental contrasting effect with prolonged dural enhancement made the differentiation difficult in this case. We speculate that dural thickening may have been overlooked with only a simple CT in some previous reports on NSF.