## Histological Types of Prostate Cancer **Key Point:** Adenocarcinoma accounts for approximately 95% of all prostate cancers, making it overwhelmingly the most common histological variant. ### Distribution of Prostate Cancer Histology | Histological Type | Frequency | Clinical Significance | | --- | --- | --- | | Adenocarcinoma | 95% | Most common; arises from glandular epithelium | | Squamous cell carcinoma | 1–2% | Rare; aggressive; poor prognosis | | Small cell carcinoma | <1% | Rare; neuroendocrine; highly aggressive | | Transitional cell carcinoma | <1% | Rare; arises from bladder involvement | ### Adenocarcinoma Subtypes **High-Yield:** Adenocarcinoma of the prostate is further classified into: - **Acinar adenocarcinoma** — most common subtype (>95% of adenocarcinomas) - **Ductal adenocarcinoma** — aggressive, higher grade - **Mucinous adenocarcinoma** — rare, intermediate prognosis - **Signet-ring cell** — rare, poor prognosis **Clinical Pearl:** The Gleason score (based on glandular differentiation) is applied to adenocarcinoma and is the most important prognostic factor in prostate cancer. It ranges from 2–10, with higher scores indicating worse differentiation and prognosis. **Key Point:** Adenocarcinoma of the prostate arises from the glandular epithelium of the acini and ducts, typically in the peripheral zone (70% of cases).
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