[Hydatid disease of the ribs]

Hydatid disease is a zoonosis resulting from the growth in man of the larval form of Echinococcus granulosus. Involvement of the bones is rare and localisation to the ribs is exceptional. The aim of our study is to present the pathophysiological and diagnostic characteristics of hydatid disease of the ribs and to define the radiological features.

We undertook a retrospective study, over a period of 10 years, of 12 cases of hydatid rib disease. We have analysed the demographic, clinical and biological parameters and we examined the radiological details as well as the effect of surgery on the progress of the disease.

The mean age of the patients was 33.5±10 years. There was no sexual predominance. The clinical picture was characterised by chest pain in ten cases and by swelling in five. General health was satisfactory in all patients. The chest X-rays showed a shadow of water density with lytic rib lesions. Thoracic CT scans showed the relationships with the neighbouring structures, particularly the spinal column. In three cases T1- and T2-weighted MRI scans showed the extent of intraspinal extension and in two cases excluded medullary involvement. Hydatid serology was positive in five cases. All our patients were operated on, with rib resection and vertebral curettage in three cases, and resection of the transverse process in two. Histological examination of the surgical specimens confirmed the diagnosis. Eight patients were treated with albendazole. All patients were reviewed for a mean of 3 years and the progress was favourable.

Hydatid disease of the ribs is a very rare disorder and the diagnosis is difficult. It is sometimes an unexpected surgical finding but careful examination of the chest X-ray, supplemented by a CT scan, thanks to the liquid density of the lesions, is a great help in diagnosis. However, in the light of the results of our series, the radiological picture may be atypical and the interpretaion difficult.