title: [Pilomatrixoma - an important differential diagnosis of facial masses].
abstract: BACKGROUND
  Pilomatrixoma are rare tumors usually arising from the sebaceous glands in the subcutaneous tissue. They are the most frequent superficially localized tumors of the cheek and parotid region in children. About 20% of all tumors in this area in children are pilomatrixoma. Currently there are only a few studies in the literature which describe characteristic findings in these tumors. The purpose of the present study was to describe clinical, sonographical and morphological characteristics of these rare tumors.
  
  
  METHODS
  Clinical records of 6 patients which were operated on for a pilomatrixoma were retrospectively analyzed. All tumors were completely excised followed by an histopathological examination on H&E stained specimens.
  
  
  RESULTS
  All patients reported about a slowly growing painless mass in the parotid area or nuchal. Sonographically tumors displayed as hyperechoic masses with a dorsal sound extinction, due to hypercalcification. Histopathologically all tumors were characterized by typical basaloid and ghost cells, accompanied by a foreign-body reaction.
  
  
  CONCLUSIONS
  Pilomatrixoma are an important differential diagnosis of unclear masses in the head and neck especially in children. The sonographical characteristics are variable and unspecific. A fine-needle aspiration biopsy is not recommended, since false malignant cytologic findings occur quite often. Therapeutically complete excision is required. Usually no adjuvant therapy is necessary, and the prognosis is good.
authors.affiliation: Klinik für HNO-Heilkunde, regionale plastische Chirurgie, Kopf- und Halschirurgie, Klinikum Nordstadt, Hannover.
authors.forename: S K
authors.initials: SK
authors.lastname: Graß
authors.affiliation: Klinik für HNO-Heilkunde, regionale plastische Chirurgie, Kopf- und Halschirurgie, Klinikum Nordstadt, Hannover.
authors.forename: C M C
authors.initials: CM
authors.lastname: Deichmüller
authors.affiliation: Pathologisches Institut, Klinikum Nordstadt, Hannover.
authors.forename: A
authors.initials: A
authors.lastname: Brandis
authors.affiliation: Klinik für HNO-Heilkunde, regionale plastische Chirurgie, Kopf- und Halschirurgie, Klinikum Nordstadt, Hannover.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Welkoborsky
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005153:Facial Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D010039:Otorhinolaryngologic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D012878:Skin Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D018615:Ultrasonography, Doppler, Color; D055815:Young Adult