title: Adrenal cysts: natural history by long-term imaging follow-up.
abstract: OBJECTIVE
  The purpose of this article is to determine the natural history of adrenal cysts on the basis of long-term imaging follow-up.
  
  
  METHODS
  This retrospective study included patients with adrenal cysts who had at least 12 months of imaging follow-up (1993-2010). Medical records were reviewed. Two radiologists reviewed imaging examinations in consensus and recorded wall thickness (thin, ≤ 3 mm; thick, > 3 mm), septations, and calcification. CT attenuation value, MRI signal intensity, the presence or absence of enhancement, and typical sonographic features were used to confirm fluid content of the lesions. Cyst wall enhancement was recorded (thin, ≤ 3 mm and smooth; thick, > 3 mm). Cyst diameter on the initial and most remote follow-up examinations was compared. The Wilcoxon matched-pairs signed rank test was applied to assess statistically significant differences in size and CT attenuation on follow-up examinations.
  
  
  RESULTS
  Twenty patients with unilateral adrenal cysts (seven male and 13 female patients; mean age, 44 years; range, 10-75 years) had a mean imaging follow-up period of 64 months (range, 12-198 months). CT, MRI, and ultrasound examinations were obtained in 19, 11, and 13 patients, respectively. Cysts were diagnosed by lack of enhancement on CT or MRI in 12 patients, typical sonographic features in three patients, and combination of CT and sonographic or MRI features in five patients. Signal intensities typical for fluid were found on all MRI examinations, attenuations of less than 20 HU on 17 of 19 (89%) CT examinations, and features of either simple or mildly complicated cysts on all sonograms. Thin walls, wall calcifications, and thin septations were found in 20 (100%), 12 (60%), and four (20%) lesions, respectively. During the follow-up of 20 lesions, the median cyst diameter increased by 26.0% (interquartile range, 6.8-68.4%) in 12 (60%) patients, decreased by 32.9% (interquartile range, 7.1-42.8%) in six (30%) patients, and was unchanged in two (10%) patients. The median baseline CT attenuation values did not significantly change on follow-up CT examinations (p = 0.72). No patient developed a complication of adrenal cyst. Four patients had histologically confirmed benign adrenal cysts.
  
  
  CONCLUSIONS
  Interval enlargement of an adrenal cyst is frequent and as an isolated finding does not indicate malignancy or presence of a complication. However, some adrenal cysts may decrease or remain stable in size over time.
authors.affiliation: 1 All authors: Department of Diagnostic Radiology, Montefiore Hospital, 111 E 210th St, Bronx, NY 10467.
authors.forename: Zina
authors.initials: Z
authors.lastname: Ricci
authors.forename: Victoria
authors.initials: V
authors.lastname: Chernyak
authors.forename: Kevin
authors.initials: K
authors.lastname: Hsu
authors.forename: Fernanda S
authors.initials: FS
authors.lastname: Mazzariol
authors.forename: Milana
authors.initials: M
authors.lastname: Flusberg
authors.forename: Sarah
authors.initials: S
authors.lastname: Oh
authors.forename: Marjorie
authors.initials: M
authors.lastname: Stein
authors.forename: Alla
authors.initials: A
authors.lastname: Rozenblit
mesh_terms: D000293:Adolescent; D000307:Adrenal Gland Diseases / Q000175:diagnosis* / Q000473:pathology; D000328:Adult; D000368:Aged; D002648:Child; D003287:Contrast Media; D003560:Cysts / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
chemical_list: D003287:Contrast Media