Histological aspects of the bladder in systemic lupus erythematosus / Aspectos histopatológicos da bexiga no lúpus eritematoso sistêmico

ABSTRACT

Objectives: to study pathological data from bladders of systemic lupus erythematosus patients, correlate them to clinical events and the use of therapeutic drugs, and compare them to bladder histopathological findings in individuals not affected by systemic lupus erythematosus. Methods: thirty-nine out or inpatients of the Department of Rheumatology at Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, diagnosed with systemic lupus erythematosus were clinically and cystoscopically evaluated. Bladder biopsy was also performed. As a normal parameter, bladders taken from 20 corpses collected at the Death Verification Department of São Paulo city, without autolysis or evidence of urinary tract or autoimmune disease were also histologically studied. This group was considered as a Control Group. A correlation among clinical, cystoscopic and histopathological data was carried out. Results: the patients mean age was 29 years (range 13-62). Thirty-six were females and three were males. Twenty-five patients were asymptomatic during the study period. In the Control Group the age range was 20-65 years. Nineteen were females (95%) and one was male (5%). Cystoscopic examination of the group with systemic lupus erythematosus showed interstitial pattern in 16 cases (41.0%) and normal in 15 (38.5%). The bladder was normal in four patients (10.3%). Chronic unspecific cystitis was observed in 18 (46.2%) patients. In the remaining, several alterations were found, including bladder vasculitis in seven patients (17.9%). The mean number of mast cells in the bladder area was 2.223/mm2. In the Control Group, unspecific cystitis was found in three cases (15.0%). No other abnormalities were found. The mean number of mast cells in this group was 0.777/mm2 (±2.7). Chronic unspecific cystitis, bladder vasculitis and the mean number of mast cells were compared with each other and no statistical differences were found (p > 0.05). There were statistically significant differences between the two groups regarding chronic unspecific cystitis and bladder vasculitis (Z = 2.078 > Z5% = 1.645 and Z = 1.777 > Z5% = 1.645) and also mean number of mast cells (Z = 2.387 > Z5% = 1.673). There were statistically significant differences between the proportion of mast cell infiltrate and presence of suprapubic pain as well as use of antimalarial drugs. The other analysis did not show statistically significant differences. There was no statistical evidence of dependence among the events cystoscopy with interstitial pattern and chronic unspecific cystitis (p > 0.237); cystoscopy with interstitial pattern and bladder vasculitis(p > 0.325); cystoscopy with interstitial pattern and mast cell infiltrate (p > 0.277). Conclusions: the bladder in systemic lupus erythematosus may be involved even in the absence of clinical manifestations. The involvement of the bladder in systemic lupus erythematosus was characterized mainly by the finding of chronic unspecific cystitis, bladder vasculitis and mast cell infiltrate. The presence of chronic unspecific cystitis was significantly greater in patients with the disease than in the Control Group, and the same occurred with bladder vasculitis. The number of mast cells/mm2 was higher than normal in patients with systemic lupus erythematosus. This finding was associated to suprapubic pain upon bladder repletion and to use of antimalarial drugs.