Histopathologic classification of parapharyngeal space tumors: a case series and review of the literature.

The objective of the study is to present a large case series of parapharyngeal space tumors (PPST) and the most comprehensive literature review of tumor histopathologic distribution. The study was designed as internal case series and full Pubmed/MEDLINE electronic database review in a tertiary academic medical center. Tumor histopathology and patient demographics were obtained from a comprehensive Pubmed/MEDLINE database review, as well from an internal case series of 117 patients referred to our center between 1993 and 2013. Main outcome and measures of the study were to define the age, gender, and histopathology of PPST within a large internal case series and among the current body of published literature, and to propose a diagnostic and treatment algorithm for these tumors. Our cohort included 117 cases, 58 females and 59 males, with benign tumors comprising 85 % (n = 99) and malignant tumors 15 % (n = 18). A systematic review of published literature from 1963 to the present revealed 37 case series, and when combined with our present series, yielded a total of 2160 cases. Benign tumors are most common (78.8 %), with tumors of salivary gland (44.4 %), neural (34.4 %), and vascular (2.64 %) origin representing the largest subtypes. Pleomorphic adenomas (30.9 %), paragangliomas (13.1 %), and schwannomas (12.3 %) comprised the majority of all cases. Due to their rarity, data regarding the histopathologic distribution of PPST is scarce. We provide one of the largest case series and the most comprehensive review of these tumors in the literature to date, and offer our algorithm for evaluation and treatment.