title: Microcystic adnexal carcinoma of the upper lip misdiagnosed benign desmoplastic trichoepithelioma.
abstract: BACKGROUND
  Desmoplastic trichoepithelioma (DT) is a benign appendageal tumour predominately localized on the facial skin. The histological diagnosis can be difficult in some cases. Partial malignant transformation of a DT is a rarity and a complete transformation has never been described in literature.
  
  
  METHODS
  A DT of the upper lip was diagnosed histologically by a small biopsy 4 years previously. At presentation, the tumour had enlarged and had partly infiltrated the left side of the upper lip and subnasal region. Histological evaluation confirmed a microcystic adnexal carcinoma but without evidence of malignant transformation of the DT. It appeared that a too-small initial biopsy had led to the incorrect histological diagnosis of a benign tumour. Thus, it was necessary to perform a tumour resection and reconstruction using a two-flap technique including a rotation flap and an Abbé flap. Functional and aesthetic outcomes were good after 6 months. There were no recurrences during a 12-month follow-up.
  
  
  CONCLUSIONS
  A facial DT should be resected completely. Patients should be attended for follow-ups, keeping in mind the difficulty of making a proper histological diagnosis from small biopsies or excisions and the consequences of ablative facial surgery. However, in particular cases, subtotal defects of the upper lip region are amenable to reconstruction without gross functional or aesthetic deficits.
authors: Department of Oral and Maxillofacial Surgery, Klinikum Bremen-Mitte, School of Medicine of the University of Göttingen, Bremen, Germany. janrustem@gmx.de
authors: Jan
authors: J
authors: Rustemeyer
authors: Stefan
authors: S
authors: Zwerger
authors: Matthies
authors: M
authors: Pörksen
authors: Klaus
authors: K
authors: Junker
mesh_terms: D001706:Biopsy; D003951:Diagnostic Errors; D004954:Esthetics; D006801:Humans; D008048:Lip Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000473:pathology / Q000601:surgery; D018294:Neoplasms, Adnexal and Skin Appendage / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D011183:Postoperative Complications / Q000209:etiology; D012086:Reoperation; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D013524:Surgical Flaps / Q000601:surgery