Correspondence: Yasushi Tanuma MD, Department of Urology, Saiseikai Otaru Hokusei Hospital, 8–18, Umegae-cho, Otaru 047–0044, Japan. Email:firstname.lastname@example.org
Abstract Adrenal cysts are a rare condition and are usually non-functioning and asymptomatic. A 44-year-old man was referred from another hospital because a left retroperitoneal tumor was incidentally found by abdominal echography. Laboratory findings including adrenal hormonal study were within the normal range. It showed homogeneously low intensity on T1-weighted images and high intensity on T2-weighted images on magnetic resonance imaging (MRI). Angiography demonstrated that the tumor was avascular and of left adrenal origin. The patient was diagnosed with left adrenal cyst and was intensively followed up with plans for examination with diagnostic imaging.
In 1903 Doran reported the first case of adrenal cyst described by Greiselius in 1670.1 Foster first summarized and reported clinical data of a total of 220 cases in 1966.2 By 1989, only about 300 cases had been reported.3 Recently, the development of diagnostic techniques such as computed tomography (CT) and ultrasonography (US) has improved our ability to detect functioning or non-functioning adrenal tumors. Clinical problems are often encountered in the diagnosis and management of adrenal tumors.
We report the case of a patient with an asymptomatic adrenal cyst that was incidentally discovered on abdominal US. We also present a brief review of adrenal cysts in Japanese published work.
A 44-year-old Japanese man was hospitalized for further examination of a left retroperitoneal tumor on January 2000. He was previously healthy, his blood pressure was normal and the abdominal examination showed no abnormal findings. Laboratory work, including initial blood counts and blood chemistry, was entirely normal. Hormonal examination, including 24 h urine catecholamines, 17-hydroxycorticosteroids, 17-ketosteroids, serum catecholamines, cortisol, aldosterone and plasma renin activities were all within normal limits. Adrenocorticotropic hormone was slightly elevated at 70 pg/mL (normal: 9–52 pg/mL).
A precontrast CT scan showed a mass measuring 70 × 55 mm located in the left adrenal region (Fig. 1). The attenuation coefficient of the mass was higher than water (40 HU). It was round with a smooth delineation and uniform density. There was no contrast enhancement in the mass lesion, but a septation and a small calcification were identified. On magnetic resonance imaging (MRI), the tumor appeared less intense than the liver in the T1-weighted image (Fig. 2a) and more intense than the liver in the T2-weighted image (Fig. 2b). Sagittal and coronal scans demonstrated the tumor was located cranially to the left kidney, medially to the spleen and posteriorly to the stomach. Abdominal arteriography demonstrated no tumor vessels in the corresponding area and showed that the mass was adrenal in origin (Fig. 3). Neither meta-iodobenzyl guanidine (MIBG) nor 131I-adosterol scintigrams demonstrated radioisotope uptake in either adrenal gland.
The patient was diagnosed with a left adrenal cyst. Invasive or surgical treatments, including puncture, alcohol fixation or laparotomy, were not performed. The patient was intensively followed up, with plans for examination by diagnostic imaging.
An autopsy study reported a 0.06% incidence of adrenal cysts in the population.4 Before 1986, only 66 cases were reported in Japan.5 Improvement in diagnostic technology now makes it possible to identify asymptomatic or non-functioning adrenal tumors, including adrenal cysts.6 We found 232 cases of adrenal cysts published in Japan before 1999 and added one personal case to make a total of 233 cases.
Adrenal cysts have been reported in patients of all ages.7 Our series ranged from birth to 77 years (average age: 45.2 years). It appears that adrenal cysts occur more frequently in women than in men in the ratio of 62 : 38. Adrenal cysts are usually unilateral and show no tendency to develop on either side.2 The side of the cyst was indicated in 228 case reports. The right side was involved in 96 cases (42.1%), the left in 131 cases (57.5%) and there was one case with bilateral involvement (0.4%).
Most adrenal cysts are asymptomatic because of their small size.2 In 48 cases (21.6%) of our series, adrenal cysts were discovered incidentally. In the case of large cysts, symptoms occur in relation to their displacement of normal organs.8 Gastrointestinal symptoms (i.e. epigastric distress, abdominal distention) are frequently present. There is an association between hypertension and adrenal cysts but the relationship has been poorly documented.9. Six patients in our series showed remission of hypertension on cyst removal. The symptoms found in the 233 patients studied are presented in Table 1.
Table 1. Symptoms in 233 patients with adrenal cysts
No. patients (%)
Lumbar pain or back pain
Palpable abdominal mass
Chills and fever
Jacobi et al. suggested that hormones in adrenal cysts probably arose by passive diffusion from the surrounding gland.10 Hormonal examination of the cystic fluid was available in 51 cases (those of pheochromocytoma are excluded) and the average concentration of cortisol, aldosterone, epinephrine and noradrenaline were higher than the normal ranges. The average values were: 105.4 μ/dL (median: 46.6); 9410 pg/mL (median: 1650); 11798 ng/mL (median: 0.14); and 93.6 ng/mL (median: 0.13), respectively.
The incidentally discovered adrenal mass will become a new clinical entity. When the mass is confirmed as a cyst by CT, MRI11 or US, conservative therapy (e.g. watch and follow or CT/US guided needle aspiration) should be adopted.12 However, if the mass can not be differentiated from a non-functioning adrenal carcinoma, surgical treatment is justified. Suzuki et al. suggested that adrenal cysts typically demonstrated low intensity on T1-weighted images and very high intensity on T2-weighted images.13 The advantages of angiography are that the blood supply of the lesion may help define its organ origin and that an avascular mass may suggest the presence of a cyst.5 Clinicians should take the invasiveness of this modality into account and use it on patients with lesions that may be malignant or of unknown origin.
Treatment of adrenal cysts depends on the underlying pathology, size of the cyst, associated symptoms and the occurrence of complications.14 Many Japanese authors recommend surgical exploration for accurate histological diagnosis to rule out malignancy and functioning tumor. Surgical exploration was done in 213 cases (92.2%) reviewed. However, with high resolution CT scan, MRI and angiography, accurate localization of adrenal cysts and assessment of their contents can be achieved. Some authors suggest that small cysts with thin walls and contents that are near water density are probably benign and can be managed by percutaneous aspiration or watch and follow.14,15 The latter was chosen as management in four cases (1.7%). Since the early 1990s, laparoscopic adrenalectomy has been shown to be safe and offers fast recovery and shorter hospital stay.16 The laparoscopic approach was performed to remove the cyst in eight cases (3.5%). Table 2 shows the types of treatments available for adrenal cysts.
Table 2. Types of treatment for 231 patients with adrenal cysts*
No. patients (%)
Two cases of autopsy are excluded.
Laparotomy (Total or partial adrenalectomy)
Fine needle aspiration (punctured)
with alcohol fixation
Not done (watch and follow)
It is now well accepted that adrenal cysts may be classified into four categories: (i) parasitic (0%); (ii) epithelial (7.5%); (iii) endothelial (29.6%); and (iv) pseudocysts (62.9%).2 Pseudocysts are the most common adrenal cysts (Table 3). These are formed when hemorrhage occurs within a normal or pathological gland with encapsulation, resulting in a thick fibrous wall without an endothelial wall.2,7 Calcification was seen in 76 of 181 (42.0%) patients and 44 of the 76 (57.9%) cases were pseudocysts. The median values of the diameter, weight and fluid volume of the adrenal cysts are: 75.0 mm (range: 5.0–310.0 mm); 102.0 g (range: 7.0–9140.0 g); and 500.0 mL (range: 2.0–11000.0 mL), respectively.
Table 3. Pathological classification of adrenal cysts in Japanese published work
No. patients (%)
True glandular (retention) cysts
Hemorrhage within normal adrenal tissue
Hemorrhage within normal adrenal tumors
Type not stated
Adrenal cysts are uncommon and most are found incidentally. Symptoms are usually related to the size and local pressure effect of the cysts. Occasionally symptoms are secondary to complications, such as, intracystic hemorrhage, rupture or infection. In the majority of cases, the cysts should be excised for accurate diagnosis or relief of symptoms and prevention of complications. Those few cases that are asymptomatic and have CT, MRI and angiographic features that are highly suggestive of a benign cyst can be managed by percutaneous aspiration or watch and follow.