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Squamous Cell Carcinoma

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  • Most common malignant tumor of the penis.
  • Incidence: South America, Africa and Asia > North America.
  • Predisposing factors: lack of circumcision, poor hygiene, phimosis, smoking and HPV infection.
  • More frequent in men >50 years old.
  • 30-40% of all SCC are HPV-related (High-risk genotypes are 16 and 18).
  • Basaloid and condylomatous (warty) SCC are HPV related (with p16 overexpression).
  • Verrucous, psedohyperplastic and cuniculatum SCCs are HPV-unrelated.
  • Patterns of growth: superficial spreading (broad horizontal superficial extension), vertical (deeply infiltrative), verruciform (superficial cauliflower growth), multicentric (>2 sites).
  • Vertical growth has higher rate of nodal involvement and poorer outcome.
  • Typical location is glans penis, coronal sulcus or prepuce (distal penis) (image A).

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  • Histology:
    • For usual type, keratinization related to differentiation (mostly have obvious keratin – well to moderately differentatied) (image B).
    • Other types include pseudohyperplastic (associated with lichen sclerosus, low grade in elderly), warty (condylomatous, with koilocytes) (image C), verrucous (see later), papillary, basaloid (non-keratinizing small to intermediate cells), sarcomatoid (spindle cell), cuniculatum (verrucous with deep burrowing and cobblestoning) and mixed.
  • p16 immunostain is a marker for high risk HPV and SCC with basaloid features and high grade nonbasaloid are likely to be more positive than low grade keratinizing SCC (image D).
  • Metastases: SCCa of the penis tends to be locally invasive but may metastasize to inguinal lymph nodes; hematogenous spread is relatively uncommon, despite the rich vascularity of the corpora cavernosa.
  • Verrucous and psedohyperplastic SCCs have low risk for nodal metastasis.
  • Basaloid, sarcomatoid, adenosquamous, and poorly differentiated usual SCCs have higher risk for nodal involvement.