Case Presentation: A 22-year-old female with a history of immune thrombocytopenia (ITP) and asthma presented with fever, altered mental status, and bilateral lower extremity petechiae. She was previously taking hydroxychloroquine daily for ITP but discontinued it on her own eight months prior. She denied any new medications, recent animal exposures, insect bites, trauma, or recent travel. Her platelet count was 6,000 /mL (normal 150,000-400,000 /mL) and her hemoglobin was 4.5 g/dL (normal 12.0-16.0 g/dL) on presentation with evidence of schistocytes and reticulocytes on peripheral smear. Her haptoglobin was undetectable, lactate dehydrogenase 474 U/L (normal 100-250 U/L), IgG Direct Coombs was positive, and ADAMTS13 was less than 5% (normal >/= 70%) with a negative inhibitor screen. This was concerning for acute TTP, although there was concern for an additional etiology given the evidence of autoimmune hemolytic anemia (AIHA), which is atypical for TTP. Her hospital course was complicated by the development of a tense, bullous rash on her upper extremities. Anti-nuclear antibody and anti-double stranded DNA antibody were positive and tissue biopsy revealed granular deposition of IgM and C3 within the walls of superficial dermal vessels and along the basement membrane zone, consistent with bullous systemic lupus erythematosus (SLE). She was treated with nine days of plasmapheresis exchange, followed by weekly rituximab for 3 weeks, and high-dose prednisone. Following an 18-day hospitalization, she completed a prednisone taper as an outpatient, and hydroxychloroquine and mycophenolate mofetil were started as suppressive therapy for SLE.
Discussion: Bullous SLE is a rare presentation of the disease, representing less than one percent of all cases of SLE. What made this patient’s presentation even more rare was that she was presenting with profound thrombocytopenia. The thrombocytopenia itself could be secondary to untreated SLE or the result of a complication from SLE like TTP. In this case, the initial concern was for TTP given the schistocytes on peripheral smear. Interestingly, the patient’s initial workup also had a positive direct Coombs test. This is atypical of TTP and suggested other possible etiologies for this patient’s symptoms, which prompted further workup. With this patient’s history of ITP and positive direct Coombs test, she met the criteria for Evans syndrome which can be secondary to SLE. The positive direct Coombs test and thrombocytopenia could also be directly related to untreated SLE. Regardless of the cause, secondary Evans Syndrome and untreated SLE are treated in the same way. In bullous SLE, dapsone can be used to treat the integumentary manifestations. Bullous SLE can also be treated with classic agents likehydroxychloroquine and mycophenolate mofetil.
Conclusions: Bullous SLE is a rare manifestation of the disease. Patients with bullous SLE can develop the same complications as other patients with SLE. This case represents a rare presentation of bullous SLE that was further complicated by profound thrombocytopenia. This was initially thought to be caused by TTP, but serologic workup revealed secondary Evans syndrome versus untreated SLE as the more likely cause for this presentation. This case highlights the variety of ways that SLE can present in the inpatient setting.