Pheochromocytomas and paragangliomas are non-epithelial neuroendocrine tumors derived from the neural crest, and their histology is similar to that of other neuroendocrine tumors of epithelial origin (NETs) . These tumors are usually negative for keratins, which helps differentiate them from epithelial NETs like carcinoid tumors . Paragangliomas (PGLs) of the head and neck are rare, comprising about 0.6% of head and neck tumors . The carotid body tumor (CBT) represents the most common type; other paragangliomas that frequently occur in the head and neck are vagal paragangliomas, tympanic paragangliomas, and jugular paragangliomas .
Carotid body tumors often present as a painless, slowly enlarging mass in the lateral neck . Differential diagnosis of a non-tender lateral neck mass includes lymphadenopathies, benign cysts, salivary gland tumors, and neurogenic tumors . Identifying the cytomorphologic features of these neoplasms and awareness of diagnostic IHC markers can help differentiate these neuroendocrine neoplasms from other tumors and provide an accurate diagnosis to the treating clinician. GATA3 is usually positive in urothelial and breast carcinomas; however, it has been recently proposed to be a potentially useful marker for the differential diagnosis of PGLs from other epithelial NETs including parathyroid neoplasms , which can show positivity for synaptophysin and chromogranin.
Of note, paragangliomas are no longer classified as benign and malignant (Since the 4th edition of the WHO). The rationale behind this paradigm shift is that any lesion can have metastatic potential and there are no clear-cut features that can predict metastatic behavior . Subsequent resection showed lymphovascular invasion and metastasis to regional lymph nodes.