A 15-year- old boy with macroscopic hematuria underwent a cystoscopy with bladder biopsy. Visualization by endoscopy shows a solitary exophytic papillary lesion (fig 4.1). At gross description, the lesion is received as multiple portions, in aggregate 2 cm x 1.5 cm x 0.3 cm. Representative cross-sections were submitted.

Sections revealed a complex papillary proliferation of urothelium. The urothelium presents normal thickness in some focal areas but in general is greater than 7 layers (fig 4.2). Superficial (umbrella) cells are absent (fig 4.3). Nuclei are uniform in shape and spacing; the chromatin texture is finely granular, without significant nucleolar enlargement (fig 4.4). Mitotic figures are rare.

Papilloma: The WHO criteria for papilloma include five strict features:

• lesion less than 2 cm in greatest dimension; (2) solitary (3) papillae consist of delicate fibrovascular cores lined by less than 7 layers of urothelium; (4) without mitotic figures or any significant cytologic atypia. Mild nuclear atypia is occasionally present; intact superficial (umbrella) cell layer; and (5) patients are less than 50 years of age.
• Papilloma is uncommon, representing less than 3 % of papillary urothelial tumors. Urothelial papilloma does not have the capacity to invade or metastasize. However, it is neoplastic, with a small but significant potential for recurrence.

Polypoid cystitis: Although classically described as being associated with indwelling catheters, this lesion may arise as a reaction to any inflammatory insult to the urinary mucosa. This lesion appears as either an area of friable mucosa irregularity, thin finger-like papillae (Papillary cystitis), or edematous and broad-based papillae (Polypoid cystitis). Abundant chronic inflammation is present within the stoma accompanied by prominent and often ectatic blood vessels.

Papillary urothelial hyperplasia: Flat or papillary urothelial hyperplasia consists of a markedly thickened mucosa with few or no significant cytological abnormalities.

Considering patient’s age, papilloma enters the major differential diagnosis (fig 4.5).

Other differential diagnosis considerations included:

• Polypoid cystitis
• Papillary urothelial hyperplasia

Non-Invasive Grade 1 (OF 3) Papillary Urothelial Carcinoma (Who 1973 Classification).

Key Features:

• Age: Usually > 50 years*
• Size: Usually > 2 cm
• Sex ratio (Male:female): 3:1
• Microscopic findings:
  • Well-formed papillae: Present
  • Thickness of urothelium: Usually > 7 layers
  • Superficial umbrella cells: Usually present, may be absent
  • Cytology
    • Nuclear enlargement: slight to modetrate
    • Nuclear hyperchromasia: Slight
    • Chromatin: Slighty coarse or granular
    • Nucleolar enlargement: May be present
  • Mitotic figures: Rare
  • Stromal invasion: Uncommon

* In the case presented here, the patient is 15- year-old. Based on histological findings (urothelium greater than 7 layers (despite normal thickness present in some areas) and absence of superficial umbrella cells)), the diagnosis of urothelial carcinoma is retained.

• Transitional cell carcinoma of the bladder occurs rarely during the first two decades of life. The malignancy is usually low grade and noninvasive, with a law recurrence rate
• Transurethral resection and fulguration is the treatment of choice, and the prognosis is excellent

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