[Assessment of the tunica muscularis mucosae of the bladder wall: necropsy study].
BACKGROUND
The bladder has traditionally been considered to lack a muscularis mucosae (MM). However in the last decade a number of studies based on biopsies or neoplastic cystectomy specimens have report the presence of a MM. Likewise, and based on the existence of such structure proposals have been made to subclassify T1 superficial bladder tumors into T1a/T1b or T1a/T1b/T1c.


METHODS
A homogeneous analysis was made of the presence of a MM in 20 necropsies of fetuses and newborns of either sex, without urological pathology. Seven different locations of the bladder wall were evaluated following intracavitary formalin fixation. A total of 140 bladder locations were thus histologically evaluated. The presence of a MM was appraised according to the patterns established by Ro et al. (1987).


RESULTS
A focal pattern was the most common presentation (62.14%) followed by a discontinuous pattern. In 32 of the 140 bladder locations (23.6%) no MM could be visualized. The location that most often exhibited a MM was the anterior bladder wall. No relations was observed between age or sex and the presence or absence of a MM. It is concluded that MM distribution in the bladder is heterogeneous and random, with a predominantly focal pattern. The MM structure was only detected over 7.78% of the mucosal surface of the bladder.


CONCLUSIONS
In recent years a modification of the TNM system has been proposed, based on the presence of infiltration of the bladder MM (T1a/T1b). The results of the present study suggest that such a classification would not very realistic since the the MM is irregular in its presentation. Nevertheless, and wherever possible, that pathologist should specify the level of infiltration of superficial bladder tumors with respect to the MM, in view of the prognostic and therapeutic implications.
Vera-Sempere
F J
FJ
Servicio de Anatomía Patológica, Hospital Universitario La Fe, Valencia.
Jaén Martínez
J
J
Vera Donoso
C D
CD
Jiménez Cruz
J F
JF
D002102:Cadaver; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009092:Mucous Membrane / Q000033:anatomy & histology; D009130:Muscle, Smooth / Q000033:anatomy & histology*; D001743:Urinary Bladder / Q000033:anatomy & histology*