Course Map: Epithelial Abnormalities: Cuboidal Metaplasia

Cuboidal Metaplasia
When the transitional epithelium (urothelium) changes to a single layer of cuboidal epithelial cells, this is cuboidal metaplasia (Fig. 1). A proliferation of this type epithelium constitutes the Nephrogenic Adenoma [35,50,72,103,117]. Such tumor-like proliferations are seen in situations of chronic irritation (stones or trauma) and, most often, at the site of a prior surgical procedure. Thus, they can occur at any age but a malignant potential has not been demonstrated. The histologic spectrum is broad. Figures 2 and 3 show a papillary or polypoid contour of the bladder mucosa with all surfaces covered by a single row of cuboidal cells.
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	Figure 1: Cuboidal metaplasia with normal urothelium on the right (arrow).
	Figure 2: Papillary contour of the bladder mucosa with all surfaces covered by a single row of cuboidal cells.
	Figure 3: Papillary and polypoid contour of the bladder mucosa with all surfaces covered by a single row of cuboidal cells.
	Figure 4: Tubules within the stroma have a resemblance to renal tubules but this is a coincidental similarity - they are not of nephrogenic origin. Larger tubules or microcysts are lined by larger, hob-nail type epithelium. Lymphocytes and plasma cells occupy the stroma.
	Figure 5: Tubules across the center of the field have prominent basement membranes. Lower left: plasma cells.
	Figure 6: Extremely small tubules have prominent basement membranes. Plasma cells are, again, a prominent feature.
	Figure 7: The cytokeratin immunostain will highlight and accentuate the morphology of the nephrogenic adenoma.
	Figure 8: When the surgical procedure which induced the formation of the NA was for carcinoma, one may see residual carcinoma and NA in the same specimen. The carcinoma is on the left (circle).