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Abstract

A man in his 70s presented with a 2-month history of painful, pruritic lesions on the left upper thighs. Lesions began as grouped small white vesicles on an erythematous base with a belt-like distribution, leading to a clinical diagnosis of herpes zoster. Oral valaciclovir for 2 weeks yielded no improvement. The eruptions gradually expanded and evolved into violaceous bullae and nodules. The patient had undergone radical distal gastrectomy for gastric adenocarcinoma 2 years earlier. Physical examination revealed diffuse erythema with clustered vesicles, violaceous nodules, and hemorrhagic bullae along the thighs. Skin biopsy showed ductal and nest-like dermal structures composed of markedly atypical cells with numerous mitoses, positive for CK7. PET/CT demonstrated widespread metastases involving the brain, liver, kidney, and lymph nodes. A diagnosis of cutaneous metastasis from gastric adenocarcinoma was established. The patient underwent resection of brain metastasis followed by systemic therapy with anlotinib and tislelizumab, achieving partial resolution of skin lesions after 3 months. Cutaneous metastases from gastric cancer are rare and usually indicate advanced disease with poor prognosis. This case highlights an unusual presentation with a zosteriform distribution and hemorrhagic bullae, easily mistaken for herpes zoster. Clinicians should consider metastatic disease in patients with a history of malignancy who develop atypical or treatment-refractory dermatoses, and perform timely biopsy to avoid misdiagnosis and delay in systemic evaluation.