UROLOGICAL SURVEY   ( Download pdf )

 

PATHOLOGY

Urothelial neoplasms in patients 20 years or younger: a clinicopathological analysis using the World Health Organization 2004 bladder consensus classification
Fine SW, Humphrey PA, Dehner LP, Amin MB, Epstein JI
Department of Pathology, Johns Hopkins Hospital, Baltimore, Maryland, USA
J Urol. 2005; 174: 1976-80

  • Purpose: Urothelial neoplasms in patients younger than 20 years are rare, with conflicting data regarding clinical outcomes.
  • Materials and Methods: We identified 23 patients 4 to 20 years old with urothelial neoplasms, reclassified the microscopic diagnoses using the 2004 WHO/International Society of Urologic Pathology grading classification and collected data on presentation, risk factors and outcomes.
  • Results: Pathological grading revealed 2 urothelial papillomas, 10 papillary urothelial neoplasms of low malignant potential (PUNLMPs), and 8 low grade and 3 high grade papillary urothelial cancers, all without invasion. Mean patient age was 13.2 years (range 4 to 20), 19 patients were male and 19 presented with gross hematuria. All lesions were solitary and measured 0.1 to 6 cm. One patient had a history of smoking and 1 had parents who smoked. Three patients (13%) had recurrences classified as either urothelial papilloma (1) or PUNLMP (2). All patients were alive with no evidence of disease after a mean followup of 4.5 years (range 6 months to 13 years).
  • Conclusions: Urothelial neoplasms in individuals younger than 20 years more commonly occur in males and are predominantly low grade with a favorable clinical outcome. Before the current classification system the 10 patients with a diagnosis of PUNLMP would have been classified as having papillary carcinoma. Thus, the diagnostic category of PUNLMP allowed 43.5% of patients in this series to avoid being labeled with “cancer” at a young age.

  • Editorial Comment
    In 1998, the International Society of Urologic Pathology (ISUP) proposed a new classification for urothelial neoplasms (1). The new classification included the so-called superficial papillary urothelial neoplasms of low malignant potential (PUNLMP). These tumors correspond to papillary urothelial carcinomas, grade 1, pTa in the traditional classification. One of the reasons for this new nomenclature is shown in the present article. Ten patients younger than 20 years had the diagnosis of PUNLMP. Two of these patients had recurrence but all were alive with no evidence of disease after a mean follow-up of 4.5 years (range 6 months to 13 years). Thus, the diagnostic category of PUNLMP allowed 43.5% of patients in the series to avoid being labeled with “cancer” at a young age. This is also valid for patients older than 20 years of age due to the low recurrence rate of these tumors.
    Considering that many urologists are unaware (or do not agree with this new classification), I have recommended to the pathologists to use both nomenclatures. PUNLMP is a papillary urothelial lesion with an orderly arrangement of cells within papillae with minimal architectural abnormalities and minimal nuclear atypia irrespective of cell thickness. In general, the major distinction from papilloma (a rare lesion), is that in papillary urothelial neoplasm of low malignant potential the urothelium is much thicker and/or nuclei are significantly enlarged. The urothelial papilloma, in contrast, has no architectural or cytologic atypia.
    Because urologists should not minimize the significance of this diagnosis, pathologists are encouraged to include the following note in cases diagnosed as papillary urothelial neoplasm of low malignant potential (PUNLMP): “Patients with these tumors are at risk of developing new bladder tumors (“recurrence”), usually of a similar histology. However, occasionally, these subsequent lesions manifest as urothelial carcinoma, such that follow-up of the patients is warranted.”
    As for the flat lesions, the ISUP recommends a new nomenclature: intraurothelial neoplasia instead of the term dysplasia/flat carcinoma in situ of the traditional classification. Grade 2 dysplasia corresponds to low-grade intraurothelial neoplasia and grade 3/flat carcinoma in situ (pTis) to high-grade intraurothelial neoplasia. ISUP recommends not to include in the pathology report dysplasia grade 1.
    For grading of urothelial papillary carcinomas, ISUP recommends call low-grade to carcinomas grade 1, and high-grade to carcinomas grade 2 or 3.

References
1. Epstein JI, Amin MB, Reuter VR, Mostofi FK: The World Health Organization / International Society of Urological Pathology consensus classification of urothelial (transitional cell) neoplasms of the urinary bladder. Am J Surg Pathol. 1998; 22: 1435-48.

Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil