Primary Subcutaneous Hydatid Cyst of the Leg After Fifteen Years of Growth

A 55-year-old man, a livestock farmer from a rural mountain area of Morocco with regular contact with dogs, presented with a painless mass of the left leg that had grown slowly over fifteen years. Examination found a subcutaneous mass, 11 cm in its long axis, firm, mobile over the deep plane, on the anteromedial aspect of the proximal third of the leg. The skin was normal and there was no neurovascular deficit. Lipoma, epidermoid cyst, organized hematoma, cold abscess and soft-tissue sarcoma were considered. Blood tests showed a moderate inflammatory response (raised C-reactive protein and leukocytosis) without eosinophilia. Plain radiographs showed a soft-tissue opacity without bone involvement. Ultrasonography showed a well-defined subcutaneous lesion with heterogeneous content and no identifiable daughter cyst. Magnetic resonance imaging showed an encapsulated cystic lesion with a thick wall of low T2 signal, heterogeneous content with detached membranes and a solid matrix and no muscular or bone extension, consistent with an old hydatid cyst, stage CE4 of the WHO-IWGE classification (World Health Organization Informal Working Group on Echinococcosis). Hydatid serology was positive. Chest and abdominal imaging found no other location. After eight days of preoperative albendazole, total pericystectomy was performed through an incision centered on the mass (Fig. 1). The operative field was protected with hypertonic saline and a protocol for anaphylaxis was ready in the operating room. The procedure lasted one hour without intraoperative rupture. The specimen, removed en bloc with its pericyst, was opened on the instrument table and yielded yellowish fluid and heterogeneous membranous content (Fig. 1); bacterial culture of the fluid was sterile. Histopathology confirmed a hydatid cyst (laminated membrane, germinal layer, protoscolices). Albendazole was continued for one month after surgery. Recovery was uneventful. Clinical and ultrasound follow-up is ongoing; at the last visit, 24 months after surgery, there was no recurrence.