Differential Diagnosis for Intravesical Protrusion of the Median Lobe of Prostate

Single Most Likely Diagnosis

• Benign Prostatic Hyperplasia (BPH): The presence of an 18 mm intravesical protrusion of the median lobe of the prostate along with significant residual urine (290/130 ml) is highly suggestive of BPH. This condition is common in older men and can cause urinary retention and bladder outlet obstruction, leading to the symptoms and findings described.

Other Likely Diagnoses

• Prostate Cancer: Although less likely than BPH given the specific findings, prostate cancer can also cause intravesical protrusion and urinary obstruction. The median lobe can be involved, and cancer should be considered, especially if there are other suspicious findings like elevated PSA levels or abnormal digital rectal examination.
• Prostatitis: Chronic prostatitis can lead to enlargement of the prostate and potentially cause some degree of intravesical protrusion, though it is less commonly associated with significant urinary retention compared to BPH or prostate cancer.

Do Not Miss Diagnoses

• Prostate Cancer with Urinary Retention: It is crucial not to miss a diagnosis of prostate cancer, as it requires prompt and specific treatment. Urinary retention can be a presenting symptom of advanced prostate cancer, making it essential to consider in the differential diagnosis.
• Neurogenic Bladder: Although less directly related to the prostate findings, neurogenic bladder due to conditions like diabetes, spinal cord injury, or multiple sclerosis can cause significant urinary retention and must be considered to avoid missing a potentially serious underlying condition.

Rare Diagnoses

• Sarcoma of the Prostate: Extremely rare, prostate sarcomas can present with rapid enlargement of the prostate and potentially cause intravesical protrusion and urinary obstruction.
• Prostatic Abscess: A prostatic abscess can cause enlargement and potentially lead to some degree of intravesical protrusion, though it would typically be associated with significant pain and systemic signs of infection.

To proceed, a thorough evaluation including PSA testing, digital rectal examination, and potentially a biopsy if cancer is suspected, along with urodynamic studies to assess the degree of obstruction, would be necessary. Imaging studies like MRI could provide further detail on the prostate and surrounding structures. Management would depend on the final diagnosis, ranging from medical therapy for BPH to surgical intervention for obstruction or cancer.