Quotation from: Manual of Surgery

Written by: Alexander Miles and Alexis Thomson

#Prognosis.#--When _natural cure_ occurs it is usually brought about by
the formation of laminated clot, which gradually increases in amount
till it fills the sac. Sometimes a portion of the clot in the sac is
separated and becomes impacted as an embolus in the artery beyond,
leading to thrombosis which first occludes the artery and then extends
into the sac.