Quotation from: Manual of Surgery

Written by: Alexander Miles and Alexis Thomson

_Diagnosis._--Before the stage of cold abscess is reached, the localised
swelling is to be differentiated from a gumma, from chronic forms of
staphylococcal osteomyelitis, from enlarged bursa or ganglion, from
sub-periosteal lipoma, and from sarcoma. Most difficulty is met with in
relation to periosteal sarcoma, which must be differentiated either by
the X-ray appearances or by an exploratory incision.