Purpose of the study: Echinococcosis is an anthropozoonosis with a predominantly muscular, more rarely osteoarticular, localisation. The purpose of this work was to describe the conditions of discovery, the diagnostic management, the serology and pathology findings, and the results of surgical treatment as well as potential complications.

Material and methods: We collected over a 16-year period, 14 cysts in eight women and six men. Mean age was 39 years (range 17–75) and delay to consultation was 36 months. The patients had an ultrasound (all 14 cases), computed tomography (n=7), MRI (n=7), hydatid serology (n=9) and pathology examination (n=10). All patients were treated surgically (7 complete resection); one patient was given associated medical treatment for a multiple localisation.

Results: Muscle hydatisosis occurred in all cases as a medium-sized tumour (mean 9 cm, range 5–16 cm) which was painful in half of the cases. One cyst was superinfected and one patient had a neurological complication. The most common site was the adductor compartment of the thigh (5 cases). Four patients had an associated visceral localization. At mean 4 years follow-up, one patient had a superinfection and two others recurrence at 7 and 10 months, with surgical revision and good outcome.

Discussion: The risk vascularisation of the thigh muscles explains these localisations. Ultrasound is a sensitive exploration which suggests the diagnosis in all cases. CT and MRI confirm the diagnosis and define the cyst relations. Pathology is needed for formal diagnosis. Total pericystectomy or wide resection is the best surgical technique, although not always readily achieved.

Conclusion: Muscle hydatidosis is rare. Treatment is surgical, different from the osteoarticular localisation, similar to the visceral foci. Recurrence is exceptional. Prevention remains the best treatment.

Purpose: Aneurysmal bone cyst is a benign osteodystrophic pseudotumor. It can occur as a primary lesion or develop on a pre-existing lesion. The etiopathogenesis, diagnosis and treatment remain subjects of interest.

Material and methods: For this retrospective analysis, we collected 48 peripheral aneurysmal bone cysts over a 27-year period. Most cysts occurred in children, adolescents, or young adults, with a slight female predominance. Imaging included standard x-rays, computed tomography, and for the more recent cases magnetic resonance imaging (MRI). MRI provided new imaging features increasing diagnostic accuracy. Second readings of histology slides enabled establishment of the correct diagnosis in certain cases but differential diagnosis was established only with benign tumours. Surgical treatment predominated. Other treatments included curettage-filling with cancellous bone, resection, resection-reconstruction,curettage-filling with cement. Adjuvant treatments mainly involved use of calcitonin. Therapeutic abstention with surveillance confirmed the possibility of spontaneous regression after biopsy. Curettage-filling with cancellous bone was performed in 58% of cases, giving an Enneking function score of 95.7%.

Results: We reviewed outcome at mean 7 years follow-up. There were four recurrent cysts and the mean global Enneking score was 95%. Our series showed the several methods can be used for the treatment of aneurysmal bone cysts, the indication taking into consideration the patient’s age, the location of the lesion and is progression. We propose a therapeutic schema. The role of calcitonin remains to be determined.

Conclusion: The diagnosis of bone cysts requires a close collaboration between the surgeon, the radiologist, and the pathologist. The indication for surgery must be made case by case to achieve cure without sequelae.