Definition
• A histological variant of SCC with papillary architecture
Clinical features
Epidemiology
• May arise from laryngotracheal papillomatosis (due to oral contamination by human papillomavirus [HPV] at the time of delivery when passing through mother’s vaginal canal or after instrumentation)
• Affects younger patients
Presentation
• Because the tumor is usually central, the patient presents with obstructive symptoms
Prognosis and treatment
• Surgical resection
• Low-stage disease at presentation has a relatively good prognosis (5-year survival: >60%)
Pathology
Gross
• Exophytic, papillary, and endobronchial growth pattern
Histology
• Well-differentiated SCC with papillary formation, with or without invasion
• When there is no invasive growth, papillary SCC is diagnosed based on cytological atypia
• Verrucous carcinoma in the lung is a very rare subtype of papillary SCC with very bland squamous epithelium and subtle invasion with pushing borders
Immunopathology/special stains
• HPV and p16 positive
• SCC markers (p63 and CK5/6) positive but not needed due to obvious squamous differentiation
Main differential diagnoses
• Papilloma: no cytological atypia, no invasion
Fig 1 Papillary variant of squamous cell carcinoma. Papillary SCC with no invasion: A, low power; B, high power. Note the cytological atypia of the tumor cells.
Fig 2 Papillary variant of squamous cell carcinoma. Papillary SCC in a 13-year-old. A, Low power showing endobronchial papillary growth; note early stromal invasion. B, Medium power showing viral changes of surface cells. C, Invasive SCC. D, Area of tracheal papillomatosis.