Misleading pustular plaques of the lower limbs during Crohn's disease: two case reports

BACKGROUND: Extraintestinal manifestations of Crohn's disease may involve the skin, the eyes, the genital mucosa, and the joints. Dermatoses associated with Crohn's disease include neutrophilic dermatoses, erythema nodosum, granulomatous dermatitis, blistering dermatoses, and non-specific skin manifestations. Cutaneous Crohn's disease is characterized by skin non-caseating epithelioid granulomatas with giant cells, remote from the gastrointestinal tract. We report herein two new cases. OBSERVATIONS: On both patients, differential diagnosis of neutrophilic dermatoses and infectious disease were evoked, and antimicrobial agents were introduced in one of them. Given the atypical presentation, the final diagnosis of cutaneous Crohn's disease could only be made with histological examination. In patient 1, the plaques decreased in size and infiltration by more than 75% after 3 weeks of treatment with bethametasone dipropionate 0.05% cream. In patient 2, the plaques decreased by more than 50% after 6 weeks of treatment with prednisolone (45 mg/day) and azathioprine (100 mg/day). DISCUSSION: Cutaneous Crohn's disease may present as dusky, erythematous, infiltrated, and ulcerated plaques and nodules. Female-to-male sex ratio is about 2, and the mean age at onset is 35. Recurrently, the hypothesis of a skin mycobacterial or fungal infection greatly delays proper treatment. Rarity of cutaneous Crohn's disease hampers therapeutic assessment in controlled trials. Thus, available literature is limited to case reports and sparse small series, with contradictory results. These reports are subject to publication bias, and no definite evidence-based recommendations can be made on the most adequate therapeutic strategy.