Objective:To explore the differentiating value of linear circular enhancement on abscess and primary necrotic tumor. Methods:CT imaging data of 112 patients and relevant pathological images of 93 patients with abscess and primary necrotic tumor confirmed by pathology,operation or clinical following-up from January 2016 to October 2018 were retrospectively analyzed. Occurrences of linear circular enhancement in two kinds of diseases were counted and the result was analyzed by using the chi-square test. Results:Among 73 patients with abscess and 39 patients with primary necrotic tumor,65 and 2 had linear circular enhancement,with percentage of 89.0% and 5.1%,respectively. Among 8 patients with misdiagnosed abscess,7(87.5%) had this sign,while 3 misdiagnosed cases of primary necrotic tumor had no sign,with significant differences between abscess and primary necrotic tumor(P<0.05). Furthermore,pathological images showed that major inflammatory granulation tissue wrapped around the necrotic area in abscess,containing many capillaries;the edge of necrosis area in tumor was tumor cells,disorderly and few nourishing vessels. Conclusion:Manifestation of lin-ear circular enhancement as inflammatory granulation tissue in enhanced CT images can an iconographical differentiating index for both abscess and primary necrotic tumor.