Purpose: Echinococciasis or hydatid disease is a cosmopolite anthropozoonosis common to many mammalian species including humans. The disease is caused by development of the larval form of a canine tenia called Echinococcus granulosus. Muscle localisations are rare.

Material and methods: We report eleven cases of hydatic disease of muscle, generally with a unique primary hydatid. The proximal muscles of the lower limbs were predominantly involved. Diagnosis was suggested in patients with a soft tissue tumour in an endemic context. Ultrasonography was highly contributive to diagnosis. Surgical treatment was given in all cases, ideally by prudent enucleation of the cyst associated with pericystecomy in four patients.

Results: Early outcome was favourable with the exception of a suppuration of the resection zone in one patient. At mid term, there has been one secondary muscle localisation far from the initial site. At 2.5 years follow-up, there have been no cases of local or distant recurrence.

Discussion: It is important to establish the diagnosis of hydatid disease of muscle before surgery in order to limit the risk of anaphylactic shock and dissemination in the event of accidental puncture. Exclusively surgical treatment is indicated.

Conclusion: Hydatid disease of the muscle is a rare event. Diagnosis is basically provided by ultrasonography, avoiding the risk of puncture. Exclusive surgical treatment removes the cyst without puncture.

Purpose: Congenital absence of the anterior cruciate ligament (ACL) is an uncommon finding. Cases reported in the literature have been sporadic. The aetiology remains obscure. The purpose of this study was to describe results obtained in five patients (eight knees) with agenesia of the ACL to determine the characteristic features and search for elements differentiating the natural course of agenesia and post-traumatic ACL rupture.

Material and methods: The patients were four men and one woman, mean age 46 years. All five patients had a common ancestor, raising the question of the hereditary nature of the condition.

Results: The cardinal sign was medial femorotibial and femoropatellar pain, found in all patients. Physical exam revealed major anterior laxity (pivot shift +, Trillat Lachman +) and an abnormal protrusion of the anterior tuberosity of the tibia. The standard x-rays revealed elements suggestive of ACL agenesia and the MRI confirmed the diagnosis in all cases.

Discussion: In comparison with reports in the literature, our patients illustrated a few specific points:

- the familial nature of the condition in our patients suggestive autosomal dominant inheritance with variable penetration;

Comparing the natural history of ACL agenesia with that of post-trauma rupture led to certain observations:

- clinical and radiological congenital laxity is well tolerated;

The lack of genetic studies and the familial nature of the cases reported here suggest that genetic surveys would be useful to elucidate this condition.