Table 2.

General features of paragangliomas of the tongue in the Chow Chow dog and human cases.

Features	Chow Chow dog	Human cases (14–18)
Anatomical location	Right side of the lingual body extending to the base of the tongue	Base of the tongue (14, 16), lateral of the middle third of the tongue (15), lingual posterior aspect (17), back of the tongue squeezing the pharyngeal cavity (18).
Clinical signs	Sialorrhea, oral bleeding during eating, halitosis, and dysphagia	Paresthesia, oral bleeding during eating (14), biting on the lesion, swelling, and pain (15), chronic throat irritation (16), asymptomatic (17), impairment of pronunciation, and sleep snoring (18).
Gross findings	Ulcerated nodule	Mass connected to the epiglottis and almost obliterating the entire oropharynx (14), swelling of the tongue (15), small granulating mass (16), single lingual nodule (17, 18).
Cytology	Round to polygonal cells, occasional acinar-like structures and naked nuclei, moderate anisocytosis and anisokaryosis, stippled nuclear chromatin, and some binucleated cells	Not accomplished (14–18)
Histology	Densely cellular rounded nests (“Zellballen” appearance), thin fibrovascular trabeculae, round to polygonal cells rounded nuclei, heterogeneous chromatin, moderate anisocytosis, and anisokaryosis, eosinophilic and granular cytoplasm PAS-negative stained.	Polygonal cells grouped in nests and surrounded by a net of thin fibrovascular septae (15–18), “Zellballen” appearance (16, 17), round nuclei within fine-grained chromatin (16–18), granular eosinophilic cytoplasm (16) PAS-negative stained (15), uniform cells without atypia, mitosis, or necrosis (16, 17).
Immunohistochemistry	CrA, SYN, VIM and GFAP positivity. S100 positivity of sustentacular cells. Melan-A, WS CK and EMA negativity.	CrA and NSE (16, 17), SYN and VIM (18) positivity. S100 positivity of sustentacular cells (16–18). CK (16–18) and melanoma marker (HMB45) (18) negativity.