Patient-attributed lunar periodicity in probable ulcerated erythema nodosum leprosum: A case report and proposed psychoneuroendocrine mechanism.

Background: Erythema nodosum leprosum (ENL) is a severe, immune mediated type 2 lepra reaction that occurs predominantly in the lepromatous spectrum of leprosy. It is characterized by the eruption of tender inflammatory nodules. The possible contribution of patient belief and the nocebo effect, on precipitating ENL, has not been examined. We present a patient with lepromatous leprosy and probable ulcerated ENL whose flares the patient reported to coincide with the full moon, raising questions about how cultural explanatory models and cognitive pattern recognition intersect with chronic inflammatory diseases. Case presentation: A 36-year-old Ethiopian male from a rural district presented with a one-year history of recurrent cutaneous bilateral lesions on his distal extremities. Individual lesions evolved from subcutaneous nodules to necrotic ulcers, and healed over up to one week, leaving hyperpigmentation at the site of each healed ulcer. Notably, the patient reported a lunar-based exacerbation pattern and initially sought spiritual healing for perceived demonic possession. Following the onset of epistaxis and nasal phonation, he sought medical evaluation. Physical examination revealed multiple non-tender nodules and clean-based ulcers, but no neurological deficits or nerve thickening. Conclusion: This case highlights a potential neuroendocrine-immune pathway through which psychological stress and illness perceptions might modulate inflammatory activity in immune-mediated leprosy reactions. It suggests the hypothesis that, in susceptible individuals, anticipatory stress responses could influence immune-mediated reactions, a concept that could be tested prospectively by correlating patient-reported flare triggers with stress biomarkers, and warrants further investigation.