Percutaneous aspiration and tetracycline sclerosis is a safe but temporary therapy of large splenic cysts in children. Between 1985 and 1987, three girls with splenic cysts were seen. Their ages ranged from 5 to 14 years, and the cysts were from 8 to 16 cm in diameter. Despite their large size, all were asymptomatic and were discovered upon physical examination or ultrasound for unrelated conditions. All cysts were avascular by scan and had irregular crenated or smooth walls by ultrasound. Further investigation excluded infectious or parasitic causes. Each cyst was aspirated for diagnosis, and a pigtail catheter was inserted for drainage and sclerotherapy. All needle aspirations resulted in cyst collapse, but in one patient the pigtail catheter insertion was unsuccessful, and in the other two cases, multiple attempts of tetracycline sclerosis failed to obliterate the cysts. There were no other complications. Surgery for the recurrent splenic cysts was performed 3 months to 2 years following the percutaneous procedures. The two patients operated on with 3 months of aspiration underwent successful partial splenectomy and have normal splenic function by ultrasound scan, and absence of RBCs. The third patient had progression of the cystic disease throughout the spleen, and required splenectomy. Pathology confirmed multiseptate congenital mesothelial cysts in the first two patients and massive lymphangiomatosis in the third. In all three cases, percutaneous therapy was safe but did not result in long-term control. In one patient, the cystic disease progressed following sclerotherapy and may have influenced the need for complete splenectomy. Prior manipulation did not adversely affect the dissection and mobilization of the spleens.(ABSTRACT TRUNCATED AT 250 WORDS)