D3.260 - Shiitake-Induced Flagellate Dermatitis: Case Series from Kazakhstan

We present a report of three patients with Shiitake-induced flagellate dermatitis, a rare inflammatory skin disease caused by consumption of raw or undercooked Shiitake mushrooms. The observations emphasize the importance of early recognition and symptomatic management of this condition.

This work helps to understand the clinical features and management of Shiitake-induced flagellate dermatitis, which may improve recognition and treatment of similar cases.

Flagellate dermatitis caused by Shiitake mushrooms is a rare condition characterized by pruritic, linear, whip-like erythematous eruptions. The exact pathogenesis is not fully understood but may involve a toxic reaction to lentinan, a polysaccharide in the mushrooms, and/or T-cell mediated immune mechanisms. Cases have been reported worldwide, mostly in countries where Shiitake mushrooms are commonly consumed.

To describe the clinical presentation, laboratory findings, and management of three patients with Shiitake-induced flagellate dermatitis.

We retrospectively analyzed three adult patients (aged 49–59 years) who developed pruritic, linear eruptions following ingestion of Shiitake mushrooms. Clinical data including symptom onset, duration, severity, and previous allergic history were collected. Laboratory investigations included complete blood count, biochemical profile, total IgE, and C-reactive protein where available. Treatment consisted of topical corticosteroids and oral antihistamines; systemic corticosteroids were used in one patient due to extensive involvement.

All three patients presented with linear, pruritic erythematous eruptions on the trunk and extremities within 24–48 hours after mushroom ingestion. Two patients had elevated total IgE (226–264 IU/mL). Treatment with topical corticosteroids and oral antihistamines led to complete resolution in 3–5 days for two patients. In the third patient with more extensive lesions and systemic symptoms, a short course of systemic corticosteroids resulted in resolution within one week. No serious adverse effects were observed.

Shiitake-induced flagellate dermatitis is a self-limiting condition that responds well to symptomatic therapy. Awareness of the disease, including its triggers and clinical course, is crucial for timely diagnosis and management. Early recognition can prevent unnecessary investigations and reduce patient discomfort.

Written informed consent for publication of anonymized clinical data was obtained from all patients.