Compliance with ethical standard

Conflict of Interests
Igor J. Koralnik was supported in part by NIH grants R01 047029 and R01 074995. The other authors all declare that they have no conflict of interest.

Ethics
Ethics approval was not required for this study.

Contributorship statement
KC, SA, NV, ST, IK and BB identified and managed the two cases. KC, SA, IK and BB wrote the first draft. JC, MR, LM, MG and AM were responsible for radiological (JC), surgical (MG) and pathological (LM, MR, AM) management and interpretation, and contributed these sections to the manuscript. All authors contributed substantially to reviewing, revising, and finalising the manuscript.

Funding
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Declaration
Dr Crossley affirms that the manuscript is an honest, accurate, and transparent account of the study being reported, and that no important aspects of the study have been omitted.

Licence and copyright
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