The good Dr. Mannion, on his last Monday of residency ever, presented a scintillating case of a young Micronesian woman with chronic skin rash & unclear history of leprosy who was admitted with recurrent fever, headache, and transient shock, found to have erythema nodosum leprosum.
Let’s start with a refresher on leprosy.
- A chronic infection caused by Mycobacterium leprae and Mycobacterium lepromatosis, leprosy classically affects the skin and peripheral nerves, and can result in severe disfigurement & disability.
- Contrary to popular belief, it is NOT highly contagious, but was viewed as a curse in the Middle Ages, leading to the formation of leper colonies, or leprosariums.
- M. leprae is enzootic in the nine-banded armadillo, although the mechanism of transmission from armadillos to humans is unknown.
- Diagnosis is established by AFB staining on skin/cutaneous nerve biopsies.
- Treatment with multidrug regimens is highly effective, and varies depending on the class of leprosy. There are 5 classes, ranging from tuberculoid (paucibacillary) to lepromatous (multibacillary) disease.
In ~30-50% of cases, immunologic reactions can occur, causing a Type I (reversal reaction) or Type 2 (erythema nodosum leprosum or ENL) reaction. Outside of this phenomenon, leprosy is not often thought to cause systemic illness. ENL presents as a sudden eruption of numerous painful nodules, along with fever, headache, and malaise. It can be confused for meningitis, as it was in this patient. It typically lasts 1-2 weeks, and is recurrent unless proper treatment is administered. High-dose prednisone is typically recommended, with thalidomide a solid alternative (though contraindicated in our patient who was of childbearing age.)