Metachronously Occurring Carcinomas of Different Histological Types in Bilateral Parotid Glands

The occurrence of multiple malignant tumors with varying histological characteristics in bilateral parotid glands has never been documented previously in the literature. Here, the authors present a noteworthy case of a patient who exhibited the sequential development of primary carcinomas, each displaying distinct histologic types within the bilateral parotid glands. This case concerns a 57-year-old male patient who initially underwent surgery, followed by adjuvant radiotherapy, for squamous cell carcinoma diagnosed in the right parotid gland. Approximately 3 years after this treatment, a novel salivary duct carcinoma emerged within the left parotid gland, prompting a second round of surgical intervention, again followed by adjuvant radiotherapy. Subsequently, a recurrent tumor was identified within the left Stensen duct, necessitating additional surgical intervention. While monitoring for recurrence or metastases remains an important aspect of post-treatment care for salivary gland cancer, it is also imperative to consider the potential for developing a second primary salivary gland cancer.