(134) Not All Rashes After Lamotrigine are SJS: A Curious Case of MIRM

Abstract:

Background: Lamotrigine is commonly prescribed as a mood stabilizer for maintenance treatment of bipolar disorder. It is preferred in reproductive age females given weight neutrality and low teratogenicity. Acute epidermolytic dermopathies are a group of distinct pathologies defined by an acute separation of the epidermis from the dermis (3); including Stevens - Johnson syndrome (SJS), Herpes-induced Erythema multiforme (EM) and Mycoplasma Pneumonia induced mucositis and rash (MIRM). The most well-known and lethal of these entities is SJS, but incidence with slow titration is 0.4% (1). We present the first reported case of MIRM in a patient on lamotrigine initially thought to be SJS.

Case Report: Ms. X is a 19-year-old female who presented with mucositis of the lips, oropharynx, and labia minora. She recently initiated lamotrigine 25mg for bipolar II disorder, which was increased to 50mg prior to admission. Her rash was considered SJS, prompting discontinuation of lamotrigine. Dermatology had MIRM high on the differential because of insignificant cutaneous involvement and her prodrome of rhinorrhea, sore throat, and cough. An IgM serology was positive for Mycoplasma Pneumonia, which confirmed MIRM. The patient was treated with methylprednisolone and fluconozole. Per patient preference, quetiapine was started in lieu of lamotrigine.

Discussion: Our patient suffered an acute epidermolytic dermopathy. There are several features that distinguish the subtypes and aid in diagnosis. First, MIRM is more prevalent in adolescents and young adults, while SJS and EM are seen mainly in adults (4). Second, MIRM is exclusively on mucosal surfaces, with lesions on the oral mucosa (94%), ocular conjunctivitis (82%) and/or genitalia (63%) (2). SJS has extensive cutaneous involvement on the trunk and extremities, which requires more comprehensive treatment than MIRM (4). Lastly, SJS is usually a drug-induced reaction while MIRM is due to an infection.

Conclusion: It is important for CL psychiatrists to consider diverse dermatologic etiologies for an acute onset erythematous rash. While the literature has highlighted SJS in patients taking lamotrigine, MIRM should be considered, especially in adolescents.

References

1. Bloom, R., & Amber, K. T. (2017). Identifying the incidence of rash, Stevens-Johnson syndrome and toxic epidermal necrolysis in patients taking lamotrigine: a systematic review of 122 randomized controlled trials. Anais Brasileiros de Dermatologia, 92, 139-141.

2. Canavan, T. N. et al(2015). Mycoplasma pneumoniae–induced rash and mucositis as a syndrome distinct from Stevens-Johnson syndrome and erythema multiforme: a systematic review. Journal of the American Academy of Dermatology, 72(2), 239-245

3. Vujic, I. et al. (2015). Mycoplasma pneumoniae‐associated mucositis–case report and systematic review of literature. Journal of the European Academy of Dermatology and Venereology, 29(3), 595-598.

4. Woolum, J. A. et al (2019). A review of the management of Stevens–Johnson syndrome and toxic epidermal necrolysis. Advanced Emergency Nursing Journal, 41(1), 56-64.