Clinical Importance of Incidental Homogeneous Renal Masses That Measure 10-40 mm and 21-39 HU at Portal Venous Phase CT: A 12-Institution Retrospective Cohort Study.

BACKGROUND. Incidental homogeneous renal masses are frequently encountered at portal venous phase CT. The American College of Radiology Incidental Findings Committee's white paper on renal masses recommends additional imaging for incidental homogeneous renal masses greater than 20 HU, but single-center data and the Bosniak classification version 2019 suggest the optimal attenuation threshold for detecting solid masses should be higher. OBJECTIVE. The purpose of this article is to determine the clinical importance of small (10-40 mm) incidentally detected homogeneous renal masses measuring 21-39 HU at portal venous phase CT. METHODS. We performed a 12-institution retrospective cohort study of adult patients who underwent portal venous phase CT for a nonrenal indication. The date of the first CT at each institution ranged from January 1, 2008, to January 1, 2014. Consecutive reports from 12,167 portal venous phase CT examinations were evaluated. Images were reviewed for 4529 CT examinations whose report described a focal renal mass. Eligible masses were 10-40 mm, well-defined, subjectively homogeneous, and 21-39 HU. Of these, masses that were shown to be solid without macroscopic fat; classified as Bosniak IIF, III, or IV; or confirmed to be malignant were considered clinically important. The reference standard was renal mass protocol CT or MRI, ultrasound of definitively benign cysts or solid masses, single-phase contrast-enhanced CT or unenhanced MRI showing no growth or morphologic change for 5 years or more, or clinical follow-up 5 years or greater. A reference standard was available for 346 masses in 300 patients. The 95% CIs were calculated using the binomial exact method. RESULTS. Eligible masses were identified in 4.2% of patients (514/12,167; 95% CI, 3.9-4.6%). Of 346 masses with a reference standard, none were clinically important (0%; 95% CI, 0-0.9%). Mean mass size was 17 mm; 72% (248/346) measured 21-30 HU, and 28% (98/346) measured 31-39 HU. CONCLUSION. Incidental small homogeneous renal masses measuring 21-39 HU at portal venous phase CT are common and highly likely benign. CLINICAL IMPACT. The change in attenuation threshold signifying the need for additional imaging from greater than 20 HU to greater than 30 HU proposed by the Bosniak classification version 2019 is supported.

Adenocarcinoma of the uterine cervix, gastric-type (GAS): a review of the literature focused on pathology and multimodality imaging.

Adenocarcinoma of the uterine cervix, gastric-type (GAS) is a rare, well-differentiated subtype of HPV-independent endocervical adenocarcinoma. It classically arises in middle-aged women with symptoms, including profuse watery vaginal discharge and abnormal uterine bleeding. Given the rarity of this disease, misdiagnosis is common and prognosis remains poorly defined. Distinct pathology and imaging findings can aid in diagnosis. A literature review was performed to ascertain recurring pathologic and radiologic characteristics of GAS. Key pathologic features of GAS include cytologically benign appearing mucinous glands that infiltrate into the deep stroma and may demonstrate lymphovascular or perineural invasion. Multiple imaging modalities including transvaginal ultrasound, CT, and MRI may aid in diagnosis of GAS, which characteristically is seen as a multicystic mass with solid components. MRI in particular is the preferred imaging study because it offers the best chance of identifying a potential solid component, which is key to making the diagnosis of GAS and distinguishing it from other endocervical diseases processes. Careful attention to histopathologic and radiologic details, in conjunction with clinical correlation, is necessary to distinguish GAS from other multicystic cervical lesions.