Shiitake Dermatitis-like Eruption Due to Tegafur/Gimeracil/Oteracil Combination Usage

Area of Science:

• Oncology
• Dermatology
• Pharmacology

Background:

• S-1 is a combination chemotherapy drug comprising tegafur, gimeracil, and oteracil potassium, developed from 5-fluorouracil.
• Drug eruptions are common adverse effects of various medications, presenting diverse clinical manifestations.

Purpose of the Study:

• To report the first documented case of S-1 causing a drug eruption that clinically mimics shiitake dermatitis.
• To highlight the importance of considering S-1 as a potential cause of specific dermatological reactions.

Main Methods:

• A case study of a 58-year-old male patient treated with S-1 for esophageal cancer.
• Clinical observation of pruritic, linear erythemas.
• Differential diagnosis including shiitake dermatitis and dermatomyositis, supported by patient history and laboratory tests.
• Histopathological examination of skin biopsy.

Main Results:

• The patient presented with a distinctive pruritic erythema in a linear pattern.
• Differential diagnoses of shiitake dermatitis and dermatomyositis were excluded based on the absence of mushroom intake, specific cutaneous signs, and relevant blood markers.
• Histopathology revealed necrotic keratinocytes, basal layer vacuolar change, and dermal inflammatory infiltrate.

Conclusions:

• S-1 was identified as the causative agent of the observed drug eruption.
• The eruption presented with clinical and histological features similar to shiitake dermatitis, emphasizing the need for careful diagnosis in patients receiving S-1.