A solitary fibrous tumor of the parotid gland: Case report

Abstract

Introduction: Solitary fibrous tumor is a rare neoplasm that can affect any part of the body, also head and neck region. Etiology is unknown. The incidence is slightly higher in males, the age ranges from 11 to 79 years. Presentation of case: It's the first case in our country of left parotid solitary fibrous tumor, removed by partial parotidectomy with facial nerve preservation. Histology examination showed diffuse spindle-shaped cells proliferation, moderate polymorphism, low mitotic index (<4 mitoses per 10 HPF), partially bordered by fibrous capsule. Immunohistochemistry showed STAT6, CD34, CD99 positivity. Six-months follow-up didn't show sign of recurrence. Discussion: Solitary fibrous tumor is a mesenchymal spindle cell neoplasm with fibroblastic differentiation ubiquitous in soft tissues, that involved the head and neck region in 6 % of cases. Etiology is unknown. The possible pathogenesis is NAB2-STAT6 gene fusion. It's asymptomatic or symptoms are related to space-occupying mass. Diagnostic work up involves imaging, immunohistochemistry, histology. Radiographic finding may lead to incorrect assessment of the mass: the same imaging features are present in pleomorphic adenoma, the most frequent tumor of salivary glands. Conclusion: This case report aims to stress that, although rare, solitary fibrous tumor should be considered in differential diagnosis in case of indolent salivary gland mass, since it may require more invasive approach (e.g., total parotidectomy, adjuvant radiotherapy). It would like to highlight the role of multidisciplinary team to define the best therapy, tailored for the patient, as well as to give awareness to a rare but sometimes aggressive tumor.