Umbrella Cell

A term for a multinucleated superficial cell of the bladder’s transitional epithelium, which has vacuolated cytoplasm. Umbrella cells are thin but cover multiple underlying transitional cells in a parasol-like fashion. They can be identified immunohistochemically by the presence of uroplakins—Ia, Ib, II, and III
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Cases of reactive atypia showed similar CK20 reactivity to normal urothelium (Apparent only in the umbrella cell layer), and p53 was at most patchy and weak, mostly in the basal cell layer.
All cases of PUNLMP showed negative p53 reactivity and CK20 positive in upper one third epithelium including umbrella cells.
Although outside the scope of the present study, findings with the rabbit primary culture system (29) suggest that further manipulation of the cell culture technique could modify the level of differentiation of the UROtsa cell cultures toward either the highly differentiated umbrella cell or the undifferentiated basal cell.
These superficial cells were identified as umbrella cells based on their ability to form junctional complexes, possession of an asymmetric unit membrane, expression of uroplakins and a 27-kDa urothelial cell-specific antigen that assembled into detergent-resistant asymmetric unit membrane particles.
The overlying urothelium was flat and appeared to be reactive rather than neoplastic, with cells with enlarged yet round nuclei with cleared chromatin and prominent nucleoli and a prominent umbrella cell layer.
Roles of uroplakins in plaque formation, umbrella cell enlargement, and urinary tract diseases.
Uroplakins, specific membrane proteins of urothelial umbrella cells, as histological markers of metastatic transitional cell carcinomas.
50) The normal urothelium shows CK20 positivity confined to the umbrella cell layer, CD44 positivity in the basal cell layer, and a weak and patchy p53 nuclear staining.
In reactive urothelium, p53 is absent to focal staining, CD44 shows diffuse or patchy staining of all layers, and CK20 stains only the umbrella cell layer.
Due to slow turnover of the umbrella cells, post-injury inflammation and hyperplasia, ethical drawbacks and animal cost, the in vivo study of urothelial differentiation and development is difficult.
The biopsy specimens diagnosed as benign on H&E (Figure 1, A through D) showed multilayered urothelium along with surface umbrella cells (cellular auto-flourescence; color-coded green) as identified on MPM.
Microscopy of biopsied Hunner's lesion demonstrating a mostly denuded surface with partial epithelization characterized by the presence of a monolayer of urothelium with umbrella cells (left upper corner).