Nephrogenic Adenomas in Pediatric Patients: An Immunophenotypic Study and Ten-Year Institutional Experience.
Jennifer B Kum, Rong Fan, John N Eble, Muhammad Idrees. Indiana University, Indianapolis
Background: In children, nephrogenic adenomas are rare benign lesions that often occur in the setting of previous surgery or chronic irritation of the urinary tract. The exact pathogenesis of nephrogenic adenoma is unknown. There is recent convincing evidence that nephrogenic adenomas are derived from renal tubular cells that are shed, migrate, reimplant and proliferate within urothelial mucosa. These lesions often present with hematuria and/or polypoid mass on cystoscopy. They frequently reoccur and can be symptomatic. We sought to evaluate the immunophenotype of these lesions in the pediatric population.
Design: We examined 20 cases of nephrogenic adenoma diagnosed from urinary bladder biopsies in 15 patients. Biopsies were obtained between 2000 and 2010. Immunohistochemistry stains for cytokeratin 7, P504S, Pax-2, Pax-5, CD10, p63 and MUC-1 (enzyme conjugated polymer visualization system) were performed. The immunohistochemistry stains for each antibody were graded for intensity on a scale from 0-3 and for extent of staining ranging from focal (0-10% of cells), partial (10-50% of cells) to diffuse (50-100% of cells).
Results: The age range was 2 to 18 years old (mean 10 years old). Nine occurred in males and 11 in females. Seven of the cases occurred in patients with history of bladder augmentation, two in patients with history of bladder stones, 1 case in a patient with history of urinary tract infection and the remaining 5 cases in patients who had other urinary bladder surgery. Strong and diffuse staining was observed with cytokeratin 7 (cytoplasmic) and MUC-1 (luminal) in all cases (100%). Strong diffuse staining was observed with Pax-2 (nuclear) in 17 of 20 cases (85%). p63 and Pax-5 did not stain any of the cases (0%). Variable staining was observed with P504S and ranged from negative (4), focal 1+ staining (9) to diffuse (7). Variable staining was also observed with CD10 and ranged from negative (2), focal 1+ staining (9) to diffuse (9). The adjacent urothelium showed a consistent immunoprofile of cytokeratin 7 and p63 reactivity and no reactivity for P504S, Pax-2, Pax-5, CD10, and MUC-1.
Conclusions: In pediatric patients, nephrogenic adenoma although rare, should be included in the differential diagnosis of polypoid lesions in the urinary tract especially in the context of previous surgery. The immunohistochemistry profile of nephrogenic adenomas in our study provides evidence that nephrogenic adenomas in pediatric patients are derived from distal renal tubular cells. In difficult cases, we recommend an immunohistochemistry panel including cytokeratin 7, p63, Pax-2 and MUC-1.
Monday, February 28, 2011 1:00 PM
Poster Session II # 198, Monday Afternoon