Cyst without a lining is :

 # Cyst without a lining is : 

a Radicular cyst 

b. Nasopalatine duct cyst 

c. Dentigerous cyst 

d. Hemorrhagic/traumatic bone cyst 

The correct answer is D. Hemorrhagic/Traumatic bone cyst.

The traumatic cyst is a pseudo cyst (lacks an epithelial lining) and an uncommon lesion comprises about 1% of all jaw cysts. It occurs in other bones of the skeleton as well.

Etiology. The etiology of the solitary bone cyst is unknown, although a number of theories have been proposed and at least one, the trauma—hemorrhage theory has been rather widely accepted. Howe and also Sieverink have carried out extensive reviews of the literature and pointed out the wide acceptance

of the theory of origin from intramedullary hemorrhage following traumatic injury. Hemorrhage occurring within the medullary spaces of bone after trauma heals in most cases by organization of the clot and eventual formation of connective tissue and new bone. According to the traumatic theory, the

clot breaks down and leaves an empty cavity within the bone. Steady expansion of the lesion occurs secondary to altered or obstructed lymphatic or venous drainage. This expansion tends to cease when the cyst-like lesion reaches the cortical layer of bone, so that expansion of the involved bone is not a common finding in the solitary bone cyst.