Renal angiomyolipoma (AML) is an uncommon renal tumour, generally composed of mature adipose tissue, dysmorphic blood vessels and smooth muscle. Identification of intratumoral fat on unenhanced CT images is the most reliable finding for establishing the diagnosis of renal AML. However, AMLs sometimes exhibit atypical findings, including cystic as well as solid forms; some of these variants overlap with the appearance of other renal tumours. A rare type of AML, the epithelioid type, possesses malignant potential. The aim of this pictorial review is to gather the different imaging features of AMLs including the classic and fat-poor types, AMLs with epithelial cysts, epithelioid AML, AML associated with tuberous sclerosis, haemorrhagic AML and large AMLs mimicking retroperitoneal liposarcomas. The diagnostic clues that help to distinguish AMLs from other renal tumours are also described in the review.

Background Paradigm shift toward nonoperative management (NOM) of adult appendicitis has made computed tomography (CT) more important than ever, particularly in differentiating complicated from uncomplicated disease. Complete surgical and pathological data of appendicitis in a place where appendectomy at initial admission is a standard of care would allow retrospective review of preoperative CT for performance and predictive ability in identifying those that may benefit from NOM in the future. Results The study included 201 CT scans of consecutive adult patients who presented for appendectomy at initial admission with pathologically confirmed acute appendicitis. Complicated appendicitis referred to gangrene or perforation on pathological or operative findings. The overall CT sensitivity, specificity and accuracy for differentiation of complicated from uncomplicated appendicitis were 87.2%, 75.7% and 81.1%, respectively. The most sensitive CT findings of complicated appendicitis were mucosal enhancement defect (83.2%; 95% CI 74.1–90.0) and moderate-to-severe periappendiceal fat stranding (96.8%; 95% CI 91.1–99.3), both independently predictive of complicated appendicitis with adjusted odds ratios (ORs) of 4.62 (95% CI 1.86–11.51) and 4.41 (95% CI 1.06–18.29), respectively. Phlegmon, fluid collection, extraluminal appendicolith, periappendiceal air and small bowel dilatation had specificity of 98.1–100%. Intraluminal appendicoliths were found more frequently in complicated appendicitis (52.6% vs. 22.6%) but not predictive for this diagnosis. Independent clinical predictors of complicated appendicitis were lack of pain migration (OR 2.06), neutrophilia ≥ 82% (OR (2.87) and symptoms ≥ 24 h (OR 5.84). Conclusions CT findings were highly accurate in differentiating complicated from uncomplicated appendicitis among patients undergone appendectomy at initial admission.

No abstract