1. A method of monitoring a patient's foot, the method comprising: forming a thermogram of the sole of at least one foot of the patient; determining whether the thermogram presents at least one of a plurality of prescribed patterns; comparing the thermogram against a prior thermogram of the same foot; and producing output information indicating the emergence of an ulcer on a given portion on the at least one foot, producing being a function of whether the thermogram is determined to present the at least one pattern, producing also being a function of the comparison, the prior thermogram showing non-ulcerated tissue at the given location.