IJRadiation therapy for recurrent hydatid cyst of the pelvic bone: a case report.

BACKGROUND: Hydatid disease usually affects the liver, but can also extend to other locations, such as the bones. In these cases, complete resection of the bone is considered the only curative approach. However, this is rarely feasible, and patients are left with benzimidazoles as their only option. In this context, there is an evident need for alternative treatments that can improve results. We present the case of a patient with a treatment-refractory hydatid cyst of the bone, who successfully underwent radiotherapy (RT).

CASE SUMMARY: A 64-year-old woman was diagnosed with a hydatid cyst of the bone in the sacroiliac joint that caused her sciatalgia and paresthesia. She underwent treatment with albendazole and surgery, and was treated with further doses of albendazole after relapsing six months later. After 2 years, she required a new resection, achieving a stable disease for 2 more years. At this point, she began to suffer from more intense pain (visual analogue scale 6/10). Given that further surgery was no longer feasible, she underwent radiotherapy (54 Gy in 27 fractions). No treatment-related toxicity was observed. At 1 month after radiotherapy, the pain had completely disappeared; 9 months later, the patient remains asymptomatic. The titer of anti-Echinococcus-granulosus antibodies and the absolute volume of eosinophils decreased after treatment with radiotherapy. The cyst remains radiologically stable.

CONCLUSION: Although further studies are needed, radiotherapy seems to be effective for hydatid cysts that are refractory to other treatments.