Wound Myiasis Complicating a Malignant Wound Caused by Merkel Cell Carcinoma of the Upper Lip: A Case Report

Wound myiasis is a relatively rare condition characterized by the infestation of an open wound with fly larvae and may complicate malignant wounds associated with locally advanced cancers. We report a case of wound myiasis complicating a malignant wound caused by locally advanced Merkel cell carcinoma (MCC) of the upper lip. An octogenarian man with MCC of the left upper lip (cT2N1M0, Stage III) developed local recurrence after radiotherapy and was subsequently treated with avelumab followed by paclitaxel. Five days after the second cycle of paclitaxel, he presented with a chief complaint of tumor malodor. Physical examination revealed approximately 20 fly larvae within the ulcerated and necrotic tumor, leading to a diagnosis of wound myiasis. The patient was treated with saline irrigation and mechanical removal of the larvae and necrotic tissue. Thereafter, daily wound care was continued, and no recurrence of myiasis was observed. In this patient, advanced age, impaired physical function, and interruption of wound care because of pain were considered to have contributed to the development of wound myiasis. Because wound myiasis is a potentially preventable complication, appropriate pain control, continuous management of malignant wounds, and the establishment of a multidisciplinary support system involving family members and caregivers are essential in elderly patients with skin cancer.