Massive transcranial parotid pleomorphic adenoma: recurrence after 30 years

Abstract

Pleomorphic adenoma, also known as benign mixed tumor, is the most common tumor affecting the parotid gland and can reach massive size; however, intracranial invasion is rare. Recurrence of pleomorphic adenoma after excision is a well-known phenomenon and can present decades after resection of the primary tumor. Here we present the case of a 53-year-old man who presented to our clinic with ear fullness, otalgia, and hearing loss 30 years after undergoing total parotidectomy and external beam radiotherapy for pleomorphic adenoma. Magnetic resonance imaging revealed a massive transcranial tumor invading the mastoid cavity, the dura of the posterior fossa, the fallopian and semicircular canals, the jugular foramen, the lateral infratemporal fossa skull base, the sigmoid and transverse sinuses, and the superior parapharyngeal region. Gross examination and histopathological studies confirmed that the mass was a recurrent pleomorphic adenoma. Here we discuss the features of recurrent pleomorphic adenoma and review the current literature.

Keywords: benign mixed tumor; carcinoma ex pleomorphic adenoma; intracranial invasion; pleomorphic adenoma; recurrent pleomorphic adenoma.

Figure 1

Preoperative magnetic resonance imaging. (A) Axial T1, (B) axial T2, (C) coronal T1, and (D) sagittal T1-weighted images reveal a variably enhancing mass in the right mastoid air cells extending medially along the floor of the posterior fossa, extending inferiorly into the parotid bed and medially into the cerebellum.

Figure 2

Histological features of recurrent mixed tumor. (A) Expansile growth of tumor extending into the mastoid causing local destruction, H&E, low magnification. (B) Cellular area of the tumor showing well-formed tubules in a chondromyxoid matrix, H&E, low magnification. (C) Paucicellular region of the tumor with abundant chondromyxoid matrix and tyrosine crystal, H&E, high magnification. (D) K _i-67 immunohistochemistry showing rare positive cell denoting a low proliferation rate.