Time course of histopathological changes after bleomycin sclerotherapy in rabbit gallbladders as a model for simple hepatic cysts

Bleomycin sclerotherapy is used in the treatment of cystic lesions; however, the histopathological changes are undefined. Present animal models of cystic diseases are not adequate for the study of sclerotherapy of hepatic cysts, primarily because the established cysts in these models are too small in size. The aim of the present study was to establish a new animal model of simple hepatic cysts, and assess the histopathological changes after bleomycin sclerotherapy. Rabbit gallbladder, with ligaturing of the cholecystic duct whilst preserving cholecystic vessels, was used as a model for simple hepatic cysts. Bleomycin (2 mg dissolved in 1 ml saline) was injected into the aspirated gallbladder, gallbladder tissue was harvested (after 1, 7, 14, 28, 42, 56 and 84 days) and histopathological changes were evaluated (n=4 per group). Additionally, control rabbit gallbladders were injected with 1 ml saline and sampled after 14 days (n=4). Histopathological changes were evaluated using hematoxylin-eosin and Masson's trichrome staining, and immunohistochemistry for CD20-, CD43- and CD68-positive cells was performed. The integrated optical density (IOD) of immunohistochemical staining and average positive stained area percentage (APSAP) of collagen were quantitatively analyzed. The results revealed gallbladders in the control group had regular epithelial cells with no visible inflammation or fibrosis. In the experimental group, epithelial cells were swollen and necrotic on the first day, and were replaced gradually by single-layer flat cells from day 56. Inflammatory infiltration was found in the submucosa, and the IOD of T cells, B cells and macrophages were highest on day 1, and these parameters declined gradually, eventually disappearing. The APSAP of collagen was highest on day 7, and gradually declined thereafter. The results suggest that histopathological changes after bleomycin sclerotherapy of a simple hepatic cyst model were characterized by sequential epithelial destruction, inflammatory cell infiltration, collagen proliferation and epithelial partial regeneration.

Sclerotherapy of Edematous Gallbladders with Different Agents

Different sclerosing agents were tried in experiments with 32 pigs to achieve ablation of gallbladders rendered edematous by mechanical lithotripsy with the Rotolith lithotriptor. In 16 pigs sclerotherapy was performed with 6% acetic acid, Carnoy's solution, 95% ethanol + 3% sodium-tetradecylsulfate (STS) and hot metrizoate, respectively. These animals were sacrificed immediately after the procedure. Histologic examination showed persistent surface epithelium and glandular epithelium in all specimens. In 6 pigs, the sclerotherapy was done with Carnoy's solution, 95% ethanol + 3% STS and hot metrizoate, respectively, and the pigs were killed 6 days later. Fibrosis of the gallbladder remnants was seen in these animals, but also remnants of surface and glandular epithelium. Hot metrizoate was used in another 10 pigs and these animals were sacrificed after 8 weeks. At histologic examination fibrosis was seen in the gallbladder remnants of 9 surviving animals, but also areas of preserved muscular layer, and development of mucinous cysts were found in more than 50% of the specimens. Thus, none of the sclerosants was able to produce a total ablation of the gallbladder mucosa.

Resectoscopic ablation of the gallbladder mucosa after cholecystostomy

PURPOSE

To investigate the feasibility of endoscopic ablation of the gallbladder mucosa after cholecystostomy.

MATERIALS AND METHODS

The mucosa of the gallbladder was endoscopically electrocoagulated through the cholecystostomy tract. After ablation, repeated luminal irrigation with chymotrypsin solution was given before removal of the tube. The patients were followed up by ultrasonography after the procedure.

RESULTS

Twenty patients accepted this operation. The mean operating time was 38 minutes (range, 25 to 55 min). There were no procedure-related mortality and complications including perforation, bleeding, and cholangitis. Eighteen gallbladders have completely obliterated in 3 months. The other 2 gallbladders developed asymptomatic retention cysts. During 48 months of follow-up period, no stone occurred and no signs of malignancy were found at the site of the gallbladder. Seven patients died from the other medical illness.

CONCLUSION

Resectoscopic ablation of the gallbladder mucosa is a safe and promising approach to sclerosis of the gallbladder after cholecystostomy.

Chemical ablation of the gallbladder

BACKGROUND

Chemical ablation of the gallbladder might avoid the need for surgery in elderly, unfit patients. This study examined the efficacy of various chemicals in destroying gallbladder mucosa.

METHODS

Ninety-five per cent ethanol, 3 per cent sodium tetradecyl sulphate (STD), trifluoroacetic acid (TFA) 2 mol/l, tetracycline 50 mg/ml, 30 and 50 per cent phenol, and a mucosal exfoliant solution (compound ethylene diamine tetra-acetic acid) were tested for gallbladder ablation in rabbits. Histology was obtained 8 weeks after exposure to these chemicals.

RESULTS

Thirty per cent phenol, tetracycline, TFA and ethanol when used as single agents were moderately effective in causing complete gallbladder mucosal obliteration, 50 per cent phenol caused a macroscopic burn of the entire gallbladder. The mucosal exfoliant solution and STD on their own did not cause mucosal destruction but had significantly enhanced efficacy when combined with 95 per cent ethanol, allowing reliable mucosal destruction with a 5-min contact duration.

CONCLUSION

Ninety-five per cent ethanol and STD after pretreatment with a mucosal exfoliant solution may be the combination of choice for in situ gallbladder mucosal ablation.

Future directions for conservative treatment of gallbladder calculi

Recent conservative gallstone treatments provide rapid relief from symptoms, but all have a potential for stone recurrence. They are indicated in patients who are unfit or unwilling to undergo cholecystectomy. Wider application will depend on selection of patients who are at least risk of recurrence, or on development of effective prophylactic strategies.