Multimodality imaging findings of an adrenal pseudocyst.

Clinical History

A 27-year-old female patient presented to the emergency department with left lateral abdominal pain lasting for two days. On clinical examination, there was tenderness on the left lateral abdominal pain but laboratory examinations and past medical history were unremarkable.

Imaging Findings

The patient was referred for abdominal ultrasound, which excluded the presence of urinary tract obstruction but identified a rounded cystic lesion situated between the tail of the pancreas and the left kidney. The mass was predominantly anechoic but contained echogenic septations and a partially thickened wall (Fig. 1). A CT examination was then requested for further evaluation, identifying a 9x11 cm lesion situated between and in close proximity to the tail of the pancreas, the spleen and the left kidney. Similarly to ultrasound, the lesion was predominantly cystic, containing limited hyperdense material, which could be attributed to haemorrhage (Fig. 2). No significant enhancement was observed within the lesion. A few days later and after conservative management, an MRI was perfomed. The lesion appeared with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, while note was made of mild capsular enhancement (Fig. 3).

Discussion

Adrenal pseudocysts are rare non-neoplastic, non-parasitic cystic masses and account for up to 40% of all adrenal cysts and 6% of adrenal incidentalomas, representing the second most common type of adrenal cystic lesion. Most of these lesions are benign and arise from the adrenal cortex or the adrenal medulla. They are found with a peak incidence between the ages of 30 and 60 years old with female predominance. Only 7% have malignant behavior or are potentially malignant. The risk of malignancy increases with size, especially when they measure more than 6cm [1, 2]. Their exact cause remains unclear, but they may be the result of reccurent bleeding, haemorrhage or infection of an endothelial cyst. As a consequence, a cavity with a fibrous irregular thickened wall but without epithelial lining is formed and progressively enlarges [1].

Adrenal pseudocysts are usually asymptomatic. Patients present with acute epigastric pain due to bleeding inside the cyst, nausea and vomiting. In cases of large cysts, symptoms may arise from pressure of adjacent organs. On clinical examination, a palpable abdominal mass is rarely found but tenderness is a common finding. Other rare clinical manifestations include adrenal hypofunction [1].

On ultrasound, adrenal pseudocysts appear as hypoechoic lesions with peripheral rim, which when enlarged cause pressure effects on adjacent organs. On computed tomography (CT) they appear as hypodense cystic lesions, occasionally calcified, but they may be found as solid heterogeneous hyperdense masses and under these circumstances, differential diagnosis from solid tumours is necessary. Magnetic Resonance Imaging (MRI) is of great importance to characterize these lesions and clarify their nature. They usually appear as unilocular or multilocular cystic lesions with high T1 signal due to their internal blood contents and low T2 signal. Septations and soft tissue components may also be found [1, 3].

According to the literature, excision of adrenal pseudocysts being hormonally active or measuring more than 5cm is recommended. Adrenal pseudocysts that are smaller than 3cm and asymptomatic should be observed with follow up for 18 months after diagnosis. A CT 3 months after first diagnosis is also mandatory [1, 2]. Percutaneous drainage of these lesions is the initial step in their management, although this is difficult due to their old haemorrhagic components. As a result, surgical excision is the most effective treatment option leading to cure of cysts carrying high suspicion of malignancy. Excluding the presence of phaeochromocytoma is an important prerequisite prior to surgery [2].

Differential Diagnosis List

Final Diagnosis

Histology after surgical resection diagnosed an adrenal pseudocyst.

URL:	https://eurorad.org/case/14366
DOI:	10.1594/EURORAD/CASE.14366
ISSN:	1563-4086