<prompt> In which one of the following prineural invasion in head and neck cancer is most commonly seenAdenocarcinomaAdenoid cystic carcinomaBasal cell adenomaSquamous cell carcinoma  <response>: Adenoid cystic carcinoma has got high affinity for perineural spreadboth axially and circumferentially;antegrade and retrograde fashion along mandibular and maxillary divisions of trigeminal common and facial nerve .It infiltrates nerve more proximally for long distance. Tumour may reach Gasserian trigeminal ganglion ,pterygopalatine ganglion and cavernous sinus SRB,5th,417. 