<p>Castleman disease is a heterogeneous group of lymphoproliferative disorders and can be categorized into unicentric Castleman disease and multicentric Castleman disease. Malignant transformation is also known to occur in the multicentric variant, however, it is rarely known to transpire in the unicentric type. The objective of this case report is to highlight the occurrence of malignant transformation into a unicentric Castleman disease of the parotid gland. We report a 25-year-old gentleman with a history of unicentric Castleman disease of the left parotid gland post excision, presented with a left parotid swelling for 4 years. The initial cytology report yielded a diagnosis of recurrent Castleman Disease. The patient successfully underwent a total parotidectomy and left modified radical neck dissection. Final histopathological reported it to be a B-cell lymphoma. The patient was referred to our Hematology colleague for initiation of treatment. The reported case showcased the importance of taking into consideration malignant transformation in unicentric Castleman disease even though it was reported to be a rare occurrence.</p>