title: Microcystic adnexal carcinoma (MAC)-like squamous cell carcinoma as a differential diagnosis to Bell´s palsy: review of guidelines for refractory facial nerve palsy.
abstract: BACKGROUND
  Bell´s palsy is the most common cause of facial paralysis worldwide and the most common disorder of the cranial nerves. It is a diagnosis of exclusion, accounting for 60-75% of all acquired peripheral facial nerve palsies. Our case shows the first case of a microcystic adnexal carcinoma-like squamous cell carcinoma as a cause of facial nerve palsy.
  
  
  METHODS
  The patient, a 70-year-old Caucasian male, experienced subsequent functional impairment of the trigeminal and the glossopharyngeal nerve about 1½ years after refractory facial nerve palsy. An extensive clinical work-up and tissue biopsy of the surrounding parotid gland tissue was not able to determine the cause of the paralysis. Primary infiltration of the facial nerve with subsequent spreading to the trigeminal and glossopharyngeal nerve via neuroanastomoses was suspected. After discussing options with the patient, the main stem of the facial nerve was resected to ascertain the diagnosis of MAC-like squamous cell carcinoma, and radiochemotherapy was subsequently started.
  
  
  CONCLUSIONS
  This case report shows that even rare neoplastic etiologies should be considered as a cause of refractory facial nerve palsy and that it is necessary to perform an extended diagnostic work-up to ascertain the diagnosis. This includes high-resolution MRI imaging and, as perilesional parotid biopsies might be inadequate for rare cases like ours, consideration of a direct nerve biopsy to establish the right diagnosis.
authors.affiliation: Department of Otolaryngology, Friedrich-Alexander University Erlangen-Nürnberg, Waldstrasse 1, Erlangen, 91054, Germany. mueller.sarinakatrin@gmail.com.
authors.forename: S K
authors.initials: SK
authors.lastname: Mueller
authors.affiliation: Department of Otolaryngology, Friedrich-Alexander University Erlangen-Nürnberg, Waldstrasse 1, Erlangen, 91054, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Iro
authors.affiliation: Department of Radiology, Klinikum Nuremberg, Nuremberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lell
authors.affiliation: Department of Neurology, Friedrich-Alexander University Erlangen-Nürnberg, Schwabachanlage 6, Erlangen, 91054, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Seifert
authors.affiliation: Department of Otolaryngology, Friedrich-Alexander University Erlangen-Nürnberg, Waldstrasse 1, Erlangen, 91054, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Bohr
authors.affiliation: Department of Otolaryngology, Friedrich-Alexander University Erlangen-Nürnberg, Waldstrasse 1, Erlangen, 91054, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Scherl
authors.affiliation: Department of Pathology, Friedrich-Alexander University Erlangen-Nürnberg, Krankenhausstraße 8-10, Erlangen, 91054, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Agaimy
authors.affiliation: Department of Otolaryngology, Friedrich-Alexander University Erlangen-Nürnberg, Waldstrasse 1, Erlangen, 91054, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Traxdorf
mesh_terms: D000368:Aged; D020330:Bell Palsy / Q000175:diagnosis*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis*; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005158:Facial Paralysis / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D008297:Male; D010306:Parotid Gland; D010307:Parotid Neoplasms / Q000175:diagnosis*
keywords: Cranial nerve resection; Facial nerve palsy; Head and neck oncology