MRI of mycetoma of the foot: two cases demonstrating the dot-in-circle sign.
Radiological and histological findings of two patients with fungal mycetoma of the foot are presented. MRI revealed multiple 2-5 mm lesions of high signal intensity interspersed within a low-intensity matrix. Within many of the lesions a minute low-intensity focus was identified. Ultrasound showed distinct hyperechoic foci within a hypoechoic mass. We speculate that the low-signal matrix represents fibrous tissue, the high-intensity lesions correspond to granulomata and the central low-signal focus to the characteristic organised fungal elements (grains) present in this condition. This "dot-in-circle sign" on MRI reflects the unique pathological features of mycetoma and is likely to be a highly specific sign for this lesion.
Sarris
I
I
Medical School, University of Oxford, Oxford, UK.
Berendt
A R
AR
Athanasous
N
N
Ostlere
S J
SJ
D000368:Aged; D005534:Foot Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008271:Mycetoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography