Tropical Medicine Central Resource

Skull and Facial Bones

Within the bones of the cranial vault, orbit and mandible the pattern followed by osteohydatid disease is that described in the following section on the skeletal system. Any cystic or blowout expansile lesion of the cranial bones (Fig. 3.124) a unilateral tumor within the orbit, or a large expansile cyst within the mandible should cause consideration of hydatid disease in a patient from an endemic area. Cranial hydatids appear to be more common in the parietal and occipital regions of the skull.

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Fig. 3.124 Hydatid cyst of the skull in three different patients. (A) Grossly expansile blowout lesion of the cranial vault seen on AP view of the skull. (B) Blowout, expansile, destructive lesion of the occiput caused by a large hydatid cyst in another patient. (C) Large lytic lesion of the posterior frontal portion of the calvariuin of a young child seen on lateral view.

Orbital Hydatid Disease

Orbital hydatid disease is not common, even in endemic areas. A preoperative diagnosis is important to avoid intraoperative cyst rupture resulting in dissemination. There is a preponderance of cases in children and young adults, typically causing painless unilateral proptosis in the superior quadrants. The extent of displacement of the eye and degree of visual impairment varies. A solitary inferolateral lesion with palpable lower lid mass can occasionally occur.

Typically, CT in orbital hydatidosis shows unilateral, hypointense, nonenhancing cysts in 70% of patients. However, hyperintense cysts, probably caused by increased protein levels in the cystic contents, may also occur (30%); this makes them easily confused with "soft tissue tumors". In children in the tropics, Burkitt's lymphoma would have to be excluded. Occasionally, the cysts may be multifocal. Bony erosion of the orbital roof or floor and destruction of the lamina papyracea and bony displacement may occur as the cysts enlarge (Fig. 3.125).

As in hydatid cysts elsewhere, fine peripheral rim enhancement has been noted after contrast injection, especially if there are superimposed inflammatory changes.

Fig. 3.125 Large hydatid cyst involving the right orbit with proptosis of the eye and compression erosion of adjacent bony structures and right ethmoid sinus.

		Skull and Facial Bones Within the bones of the cranial vault, orbit and mandible the pattern followed by osteohydatid disease is that described in the following section on the skeletal system. Any cystic or blowout expansile lesion of the cranial bones (Fig. 3.124) a unilateral tumor within the orbit, or a large expansile cyst within the mandible should cause consideration of hydatid disease in a patient from an endemic area. Cranial hydatids appear to be more common in the parietal and occipital regions of the skull. ..... Fig. 3.124 Hydatid cyst of the skull in three different patients. (A) Grossly expansile blowout lesion of the cranial vault seen on AP view of the skull. (B) Blowout, expansile, destructive lesion of the occiput caused by a large hydatid cyst in another patient. (C) Large lytic lesion of the posterior frontal portion of the calvariuin of a young child seen on lateral view. *Orbital Hydatid Disease* Orbital hydatid disease is not common, even in endemic areas. A preoperative diagnosis is important to avoid intraoperative cyst rupture resulting in dissemination. There is a preponderance of cases in children and young adults, typically causing painless unilateral proptosis in the superior quadrants. The extent of displacement of the eye and degree of visual impairment varies. A solitary inferolateral lesion with palpable lower lid mass can occasionally occur. Typically, CT in orbital hydatidosis shows unilateral, hypointense, nonenhancing cysts in 70% of patients. However, hyperintense cysts, probably caused by increased protein levels in the cystic contents, may also occur (30%); this makes them easily confused with "soft tissue tumors". In children in the tropics, Burkitt's lymphoma would have to be excluded. Occasionally, the cysts may be multifocal. Bony erosion of the orbital roof or floor and destruction of the lamina papyracea and bony displacement may occur as the cysts enlarge (Fig. 3.125). As in hydatid cysts elsewhere, fine peripheral rim enhancement has been noted after contrast injection, especially if there are superimposed inflammatory changes. Fig. 3.125 Large hydatid cyst involving the right orbit with proptosis of the eye and compression erosion of adjacent bony structures and right ethmoid sinus. Next Page Previous Page