Atypical MRI presentation of a small splenic hamartoma

Hamartomas of the spleen usually appear isointense on T1-weighted MR images and hyperintense on T2-weighted images. We describe a histologically proven case which presented as a small (2.5 cm) focal mass isointense to splenic parenchyma on T1-weighted images and hypointense on both turbo-spin-echo T2 and short T1 inversion recovery images. Dynamic MRI revealed a delayed enhancement during the arterial phase becoming isointense and prolonged on subsequent images. This prolonged enhancement has previously been described as a characteristic pattern in these tumours. The lack of oedema and necrosis and the presence of fibrous tissue in the hamartoma at histopathology likely account for the low signal intensity on all sequences.