To the Editor Dr Chatterjee, in his case presentation of a patient with diabetic scleredema,1 did not explain the rationale for ordering a serum immunofixation. Presumably, it was ordered to evaluate the patient for the possibility of multiple myeloma. However, based on the patient’s presentation and absence of anemia, renal insufficiency, hyperproteinemia, hypercalcemia, or osteolytic lesions, plasma cell disorders should not have been high on the list of possible diagnoses.2,3 In addition, if a plasma cell disorder was suspected, a serum protein electrophoresis study with serum free light chain testing would have been more appropriate,4,5 as those tests in combination have a sensitivity of 100%, specificity of 97%, positive predictive value of 60%, and a negative predictive value of 100% for the diagnosis of plasma cell disorder.
Alter D. Laboratory Testing in the Setting of Diabetic Scleredema. JAMA. 2016;316(5):542. doi:10.1001/jama.2016.6644