basaloid squamous cell carcinoma

Introduction

High grade agressive squamous cell carcinoma variant.

Pathology

Predilection for head & neck, occurs in larynx, hypopharynx, tonsils, base of tongue, oral cavity, nasopharynx, trachea, sinonasal tract.

Microscopic pathology

• predominantly basaloid appearing cells
  • hyperchromatic nuclei
  • marked nuclear pleomorphism
  • eosinophilic to amphophilic clear cytoplasm
• variable nucleoli
• confluent foci of central necrosis
• individual cell necrosis
• peripheral nuclear pallisading
• foci of squamous cell differentiation
• intermixture of squamous & basaloid cells
• infiltrative, mostly lobular or solid Immunohistochemistry:
• pan-cytokeratin: +
• EMA: + variable amount & pattern
• CAM 5.2: + 12/14
• CEA: + 4/14
• CK7: + 10/14
• CK20: + 1/14 focal
• 34betaE12: + 12/14
• S100 + 6/14
• NSE: + 10/14
• GFAP: + 2/14
• vimentin: + 8/14
• muscle specific actin (HHF35): + 7/14
• Ewing's marker (MIC-2): + 7/14
• chromogranin, synaptophysin, neurofilament protein, HMB-45, desmin, leukocyte common antigen: negative

Differential diagnosis

• undifferentiated small cell carcinoma

More general terms

• squamous cell carcinoma (SCC)