title: Basal cell carcinoma involving the lacrimal canaliculus. A documented mechanism of tumor spread.
abstract: BACKGROUND
  Basal cell carcinoma (BCC) is the most common malignant tumor of the eyelid and periocular tissues but rarely involves the lacrimal system. In addition, BCC in this location frequently recur due to inadequate margin control. A further understanding of the pathophysiology of periocular BCC was addressed.
  
  
  OBJECTIVE
  To report two rare cases of BCC involving the lacrimal system and to account for subtle clinical features yet extensive tissue spread of periocular BCC.
  
  
  METHODS
  Using the Mohs micrographic surgical technique, we describe two patients with a BCC involving the lacrimal system that histologically tracked beyond clinically apparent margins.
  
  
  RESULTS
  Spread of BCC along mucosal surfaces is documented.
  
  
  CONCLUSIONS
  Rare involvement of the lacrimal system by a BCC is reported in two patients. Superficial histologic involvement can explain the ability of BCC to extend locally and escape adequate treatment.
authors.affiliation: Department of Dermatology, Saint Louis University Health Sciences Center, Missouri 63104, USA.
authors.forename: S W
authors.initials: SW
authors.lastname: Fosko
authors.forename: M D
authors.initials: MD
authors.lastname: Gibney
authors.forename: J B
authors.initials: JB
authors.lastname: Holds
mesh_terms: D000328:Adult; D002280:Basal Cell Carcinoma / Q000473:pathology* / Q000601:surgery; D005134:Eye Neoplasms / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007766:Lacrimal Apparatus Diseases / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D015580:Mohs Surgery; D009361:Neoplasm Invasiveness