Serologies in Lyme disease can be deceiving: a rare case of mycoplasma-induced figurate erythema with persistent IgM Lyme antibodies

We present the case of a 65-year-old woman who came to our clinic with a pruriginous annular skin eruption suggestive of erythema migrans. She reported a previous mild respiratory syndrome. Given the suspicion, the patient was empirically given doxycycline 100 mg q12h for two weeks, which led to a resolution of the dermatosis. Initially, laboratory tests revealed positive IgM for Lyme disease, however these IgM persisted for several months of longitudinal follow-up and IgG was never positive. Seroconversion occurred, however, for <i>Mycoplasma pneumoniae</i> over the course of three weeks. <i>M. pneumoniae</i> is known to cause mucositis, but to our knowledge this is the first reported case of Mycoplasma-induced figurate erythema. She maintained longitudinal follow-up at our clinic and showed no signs of recurrence during this period.