右側結腸（A：上行結腸，C：盲腸）を中心に，図１と図２では横行結腸（T）まで，尾側では図１４の回腸末端(TI)まで広範囲に粘膜下浮腫による壁肥厚を呈し，腸炎特に感染性腸炎を強く示唆する．図１３で虫垂根部を認識できるがそれから先の走行ははっきりしない．しかし，図１２〜図１５の蜂窩織炎像（↑）は，虫垂を中心にした強い炎症を示唆し，図８〜図１１の脂肪組織の濃度上昇（▲）と，図１３〜図１７の小腸壁肥厚（△）もそれを裏付ける所見である．腸炎に合併した，進行性（穿孔性または壊死性）の急性虫垂炎と診断した．手術所見：盲腸と虫垂が一塊の腫瘤を形成し，虫垂は盲腸に強く癒着し剥離不可能であった．盲腸腫瘍の可能性も否定できず回盲部切除を行った（図A）．図Bでは盲腸と回腸末端に粘膜下浮腫による壁肥厚を示している（白矢印）．病理：gangrenous appendicitis．回腸と盲腸はsubacute inflammationを示す腸炎．

文献考察：CT所見と虫垂炎の重症度は一致する．
１）Arch Surg. 2004 Dec;139(12):1304-8.
Histologic severity of appendicitis can be predicted by computed tomography.
Hansen AJ, Young SW, De Petris G, Tessier DJ, Hernandez JL, Johnson DJ.

HYPOTHESIS: A regression model based on computed tomographic (CT) findings alone can accurately predict the histologic severity of acute appendicitis in patients who have a high disease likelihood. DESIGN: Retrospective study. SETTING: Mayo Clinic in Scottsdale, Ariz. PATIENTS: Consecutive sample of 105 patients (50 women and 55 men, aged 15-89 years) undergoing nonincidental appendectomy within 3 days of nonfocused abdominal CT. INTERVENTIONS: Computed tomographic scans and histologic features were retrospectively reinterpreted. Each patient's histologic and CT findings were scored by standardized criteria. An ordinal logistic regression model was constructed with a subset of CT findings that statistically correlated best with the final histologic features. Predicted severity values were then generated from the model. MAIN OUTCOME MEASURE: Agreement between predicted and actual histologic severity, using weighted kappa measurement. RESULTS: Computed tomography variables used in the model were fat stranding, appendix diameter, dependent fluid, appendolithiasis, extraluminal air, and the radiologist's overall confidence score. The weighted kappa measurement of agreement between predicted and actual histologic severity was 0.75, with a 95% confidence interval between the values of 0.59 and 0.90. CONCLUSIONS: Computed tomographic findings, when used with the regression model developed from this pilot study, can accurately predict the histologic severity of acute appendicitis in patients initially seen with a high clinical suspicion of the disease. These findings provide a platform from which to prospectively test the model.PMID: 15611455

２）Radiat Med. 2001 Jul-Aug;19(4):197-202.
Enhanced CT in the diagnosis of acute appendicitis to evaluate the severity of disease: comparison of CT findings and histological diagnosis.
Mori Y, Yamasaki M, Furukawa A, Takahashi M, Murata K.
PURPOSE: To assess the potential of CT in evaluating the histological severity of acute appendicitis in comparison with surgical and pathological findings. METHOD: The CT images of 75 patients with surgically proven appendicitis, including 10 cases of catarrhal, 34 of phlegmonous, and 31 of gangrenous appendicitis, were retrospectively analyzed for the following five CT findings: (1) hazy periappendiceal densities, (2) enlarged appendix, (3) increased enhancement of the appendiceal wall, (4) increased enhancement of the periappendiceal intestinal wall, and (5) deficiency of the appendiceal wall. By comparing all the CT findings and the pathological severity of appendicitis (catarrhal, phlegmonous, and gangrenous), the prevalence of the five CT findings was calculated for each pathological category. RESULTS: Abnormal CT findings were noted in only one case of catarrhal appendicitis. Increased enhancement of the appendiceal wall was observed in all 29 cases of phlegmonous appendicitis (100%), but in only 66.7% (18 cases) of gangrenous appendicitis. Deficiency of the appendiceal wall was more frequently observed in gangrenous (19/27, 70.4%) than phlegmonous appendicitis (4/29, 13.8%). CONCLUSION: Findings of enhanced CT provide useful information in evaluating the pathological severity of acute appendicitis.PMID: 11550720（full text）