[Osseous echinococcosis. Apropos of 6 anatomo-clinical observations]

Concerning these six cases, the authors recall the rarity of osseous localization of Hydatidiform disease, isolated as a rule, arising in the adult and preferentially involving the ilium, spinal column, femur, humerus and scapula. Being slowly progressive, the condition is revealed by pain, swelling and above all spontaneous fractures (long bones), or signs of root or medullary compression (spinal column), followed sometimes by fistula formation. Radiological diagnosis is often difficult with an osteolytic appearance without appreciable reactional osteogenesis. As for laboratory investigations, they are only of value in orientation; immunofluorescence being the weakest. The extent of osseous lysis frequently demands extensive surgery. From the anatomical standpoint, the hydatid variety of Echinococcosis has a specific intra-osseous development: beginning in the spongy bone, the architecture is intermediary between the hydatid appearance and the alveolar variety. Some cases however comprise a unilocular appearance with a suspicion of adventitial reaction. Extension into the soft parts frequently adopts a macroscopic appearance identical with that of visceral forms. Bony lysis is dependant on osteoclastic resorption or foci of necrosis while reactional osteogenesis is reduced. Medullary cellular reactions are determinant in the anatomical progress: osteitis or histiocyte and plasmodial reaction to the cuticle fragments.