[RD (OP)]

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Main image ... http://en.chinafotopress.com/index/onegroup?gid=7154412  [ ID:429902432 ]

Monochrome inset ... http://syndromepictures.com/proteus-syndrome-pictures/  [ bottom of page ]

[CliffordK]

Proteus sounds like a reasonable preliminary diagnosis. 
There apparently is a genetic test for AKT1 kinase defects, perhaps in a mosaic pattern.

One might expect the possibility of involvement in other parts of the body.  One would, of course, also ask about medications during pregnancy, and look for other similar cases in the family, and in the country.

Lymphatic problems might be on the differential diagnosis, but seem to cause more swelling where this seems to be more soft tissue overgrowth.

A tumor or cancer might be expected to be more localized to a single body part.  Arthritis and gout would have more bone involvement, and less soft tissue involvement.

The kid needs a good cobbler.

[RD (OP)]

Lymphatic problems might be on the differential diagnosis, but seem to cause more swelling where this seems to be more soft tissue overgrowth. 

The bones of her feet have enlarged too, so not lymphatic like elephantiasis.

Proteus syndrome is supposed to be asymmetrical though ... https://en.wikipedia.org/wiki/Proteus_syndrome#Presentation

http://www.google.co.uk/search?q=macrodactyly+foot+bilateral

http://en.wikipedia.org/wiki/Local_gigantism

www.google.co.uk/search?q=foot+gigantism+bilateral

http://www.ncbi.nlm.nih.gov/pubmed?term=pedal%20macrodactyly%20bilateral