A common cause of false-positive urine cytology is instrumentation artifact, such as from catheterization, cystoscopy, or recent surgery. These procedures cause mechanical trauma to the urothelium, leading to reactive cellular changes that can mimic malignancy. Reactive urothelial cells may show nuclear enlargement, prominent nucleoli, and increased N/C ratios, but they typically maintain uniform chromatin and smooth nuclear membranes. Other causes of false positives include viral infections (e.g., polyomavirus, CMV), lithiasis (stone-induced atypia), chemotherapy/radiation effects, and inflammation. Distinguishing reactive atypia from true malignancy requires careful evaluation of chromatin pattern, nuclear membrane irregularities, and clinical history to avoid unnecessary interventions.

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Zambia

• Joseph Soko – 101 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies