Hyperpigmentation on head and neck caused by polymyxin B: A rare case.

Polymyxin B was widely used to treat drug-resistant gram-negative bacteria and showed a better antibacterial effect. However, it is associated with some side effects. It should be remembered that polymyxin B may cause hyperpigmentation, albeit rare. This is a case report of a 68-year-old male patient who developed hyperpigmentation following treatment of a chest infection with polymyxin B. He was a known patient with chronic kidney diasease and chronic obstructive pulmonary disease followed up in the intensive care unit due to acute exacerbation of COPD. Later, polymyxin B treatment was started due to the development of pneumonia caused by the multidrug-resistant Acinetobacter baumannii. On the second day of polymyxin B treatment, hyperpigmentation developed in the face and neck region. The fact that the patient had chronic kidney disease possibly facilitated the development of skin hyperpigmentation due to the cumulative effect of polymyxin B. Hyperpigmentation which a rare side effect of polymyxin B may occur in those with underlying kidney disease.