Failure to improve may be due to:
(1) misdiagnosis (livedo reticularis, etc)
(2) development of a secondary malignancy
Secondary malignancies that may develop at a site of chronic erythema ab igne include:
(1) squamous cell carcinoma
(2) Merkel cell carcinoma
(3) malignant lymphoma
Some patients develop erythema ab igne because of another underlying problem:
(1) chronic pancreatitis (use of a heating pad on the abdomen because of chronic abdominal pain)
(2) diabetic or other neuropathy (as a source of chronic pain and an inability to detect excessive heat exposure)
(3) cancer (use of heating pad because of chronic pain)
(4) other form of chronic pain
