Classifications of tumor severity and extent for head and neck paragangliomas

Fisch classification^[1,2]
Class A	Tumors that arise along the tympanic plexus on the cochlear promontory
Class B	Tumors with invasion of hypotympanon; cortical bone over jugular bulb intact
Class C₁	Tumors with encroachment of the carotid foramen, but no invasion of the carotid artery
Class C₂	Tumors with destruction of the vertical carotid canal
Class C₃	Tumors that invade the horizontal portion of the carotid canal, but do not reach the foramen lacerum
Class C₄	Tumors with growth to foramen lacerum and along the carotid artery and the cavernous sinus
Class De_1/2	Tumors with intracranial but only extradural extension; De_1/2 according to displacement of dura (De₁ = less than 2 cm, De₂ = more than 2 cm)
Class Di_1/2/3	Tumors with intracranial and intradural extension; Di_1/2/3 according to depth of invasion into posterior cranial fossa (Di₁ = less than 2 cm, Di₂ = between 2 and 4 cm, Di₃ = more than 4 cm
Jackson/Glasscock classification^[3]
Type 1	Small tumor involving the jugular bulb, middle ear, and mastoid process
Type 2	Extending under internal auditory canal; may have intracranial extension
Type 3	Extending into petrous apex; may have intracranial extension
Type 4	Extending beyond petrous apex into clivus or infratemporal fossa; may have intracranial extension

References:

Fisch U, Mattox D. Microsurgery of the skull base. Thieme, Stuttgart-New York, 1988, page 149.
Boedeker CC. Paragangliomas and paraganglioma syndromes. GMS Curr Top Otorhinolaryngol Head Neck Surg 2011; 10:Doc03.
Jackson CG, Glasscock ME 3rd, Harris PF. Glomus Tumors. Diagnosis, classification, and management of large lesions. Arch Otolaryngol 1982; 108:401.

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