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- Presentation
Ketogenic Diet–Associated Prurigo Pigmentosa in a Patient With Refractory Status Epilepticus
Description
A man in his 30s with new-onset refractory status epilepticus in the neuro-ICU developed a patchy red-to-brown papular reticulate rash on the trunk, neck, and back that initially raised concern for drug eruption, DRESS, autoimmune disease, or viral exanthem. Extensive infectious, autoimmune, and metabolic workups were negative, and biopsy showed interface dermatitis with a lymphocytic infiltrate and some eosinophils. Careful bedside review revealed that the eruption appeared in crops, with older hyperpigmented lesions and newer inflamed lesions, prompting a broader differential that eventually uncovered an important clue: he had been started on a ketogenic diet 13 days before the rash began. The final diagnosis was prurigo pigmentosa associated with ketosis, a distinctive truncal eruption triggered by ketotic states. The speaker reviewed its classic morphology, histology, and pathophysiology, emphasizing that biopsy findings depend on lesion age, and noted that the patient improved with topical mid-potency steroids while seizure medications were restarted.
View moreConclusions
- The patient’s eruption was ultimately best explained by prurigo pigmentosa associated with ketosis rather than drug hypersensitivity or autoimmune disease.
- A ketogenic diet can trigger a distinctive truncal papular eruption that evolves in crops, with new inflamed lesions and older hyperpigmented lesions coexisting.
- The clinical pattern of reticulated red-brown papules on the trunk with post-inflammatory hyperpigmentation is often more diagnostic than the initial biopsy.
- Skin biopsy may show a stage-dependent inflammatory pattern, so its usefulness depends on when the lesion is sampled.
- In complex hospitalized patients, careful attention to morphology, lesion timing, and medication/nutrition exposures is essential to avoid misdiagnosis.
- Ketogenic diets used for refractory seizures can cause unexpected dermatologic adverse effects and should be included in the differential diagnosis.
- The case highlights that metabolic states, including ketosis, can produce dynamic and underrecognized skin findings.
- Once the dietary trigger was recognized, the eruption was managed conservatively with topical corticosteroids while seizure therapy could be resumed.
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