Periocular Pigmentation After Gemcitabine Monotherapy for Bladder Cancer: A Rare Case Report

A patient with advanced bladder cancer received antitumor therapy consisting of gemcitabine on days 1 and 8 combined with cisplatin and treliprimab on day 1. Severe periorbital hyperpigmentation occurred 30 min after gemcitabine infusion on day 8. Symmetrical diffuse hyperpigmentation of a dark brown hue with indistinct borders appeared around the affected eye, extending to the orbital and facial regions along the orbital margin. No accompanying symptoms, including pruritus, pain, or desquamation, were observed. The patient had no prior history of dermatological conditions and no family history of skin disorders. During chemotherapy, no other drugs, cosmetics, or specific foods known to induce skin hyperpigmentation were used. No additional abnormalities were identified during dermatological examination. Laboratory tests, including liver function indicators such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) within the range of 10-40 IU/L, kidney function parameters such as blood urea nitrogen (BUN) 2.8-7.1 mmol/L and creatinine 50-96 μmol/L, blood glucose levels of 3.9-6.1 mmol/L, thyroid function within normal limits, and electrolytes including sodium (Na) 135-145 mmol/L and potassium (K) 3.5-5.5 mmol/L, were all within their respective normal ranges. Considering the patient's medical background, treatment regimen, and the temporal relationship between the onset of symptoms and chemotherapy cycles, this periorbital hyperpigmentation likely represents a transient adverse reaction to gemcitabine, as supported by previously reported cases. Within 2 days after chemotherapy cessation, the periorbital hyperpigmentation improved significantly. This case highlights that during gemcitabine administration, clinicians should remain vigilant for rare adverse reaction of gemcitabine-induced periorbital hyperpigmentation. Close skin monitoring throughout treatment is essential, and prompt evaluation and intervention should be carried out to improve the patient's quality of life.