Leprosy and monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell proliferative disorder with a prevalence of 3 % in patients aged 50 years and older. Many dermatological and non-dermatological conditions are known to be associated with MGUS. Some of these conditions show statistically significant associations with MGUS, while others are coincidental. We describe a 56-year old woman with borderline lepromatous leprosy who presented with a monoclonal band on serum protein electrophoresis and a bone marrow trephine biopsy suggestive of MGUS.