title: Two different scenarios of squamous cell carcinoma within advanced Basal cell carcinomas: cases illustrating the importance of serial biopsy during vismodegib usage.
abstract: OBJECTIVE
  Vismodegib is a Hedgehog signaling pathway inhibitor recently approved by the US Food and Drug Administration for advanced basal cell carcinoma. We present 2 cases of clinically significant squamous cell carcinoma within the tumor bed of locally advanced basal cell carcinoma found during vismodegib treatment.
  
  
  METHODS
  The first case is that of a patient with locally advanced basal cell carcinoma responsive to vismodegib but with an enlarging papule within the tumor bed. On biopsy, this papule was an invasive acantholytic squamous cell carcinoma. The second case is that of a patient with Gorlin syndrome with a locally advanced basal cell carcinoma that was stable while the patient was receiving therapy with vismodegib for 2.5 years but subsequently increased in size. Biopsy specimens from this tumor showed invasive squamous cell carcinoma, spindle cell subtype. In both cases, the squamous cell carcinomas were surgically resected.
  
  
  CONCLUSIONS
  These cases highlight the importance of repeated biopsy in locally advanced basal cell carcinomas in 2 clinical situations: (1) when an area within the tumor responds differentially to vismodegib, and (2) when a tumor stops being suppressed by vismodegib. Timely diagnosis of non-basal cell histologic characteristics is critical to institution of effective therapy.
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, Redwood City, California.
authors.forename: Gefei A
authors.initials: GA
authors.lastname: Zhu
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, Redwood City, California2Department of Pathology, Stanford University School of Medicine, Stanford, California.
authors.forename: Uma
authors.initials: U
authors.lastname: Sundram
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, Redwood City, California.
authors.forename: Anne Lynn S
authors.initials: AL
authors.lastname: Chang
mesh_terms: D000328:Adult; D000813:Anilides / Q000627:therapeutic use*; D001706:Biopsy; D002280:Basal Cell Carcinoma / Q000188:drug therapy* / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000188:drug therapy* / Q000473:pathology*; D011725:Pyridines / Q000627:therapeutic use*; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000473:pathology*
chemical_list: D000813:Anilides; C538724:HhAntag691; D011725:Pyridines