• Squamous cells not normally present in pancreas, so four theories have been proposed:
  • Metaplasia of pancreatic ductal epithelium present during inflammation (eg during pancreatitis)
  • Pluripotent progenitor cell capable of differentiating to adeno or squamous undergoes malignant transformation
  • Pre-existing adenocarcinoma undergoes transformation to squamous cell
  • Aberrant squamous cell undergoes malignant transformation
• Reported incidence between 0.005% (pure squamous) and 2% (adenosquamous) tumors of pancreatic tumors
• 61 cases reported in English literature (PMID 16208119)
  • Mean age 62 years
  • Presenting symptoms: abdominal or back pain, weight loss, anorexia
  • Average tumor size 7.8 cm
  • Equal distribution between head, body and tail
  • Median survival: resected 7 months, non-resectable 3 months
• Given its rarity, it is important to exclude metastatic disease from elsewhere
• Enhances on triphasic contrast CT
• Consider gemcitabine-based chemotherapy

Adenosquamous carcinoma

• PMID 10367867, 1999 — "Adenosquamous carcinoma of the pancreas." (Madura JA. Arch Surg. 1999 Jun;134(6):599-603.)
  • Retrospective review of 6 patients
  • Approximately 4% of all pancreatic neoplasms (only 134 cases reported at the time of publication - 1999)
  • Discussion states positive Ca 19-9, ST 439, keratin staining
  • Survival = 5.4 +/- 4 months