Overview of adrenal venous drainage through a case of adrenocortical carcinoma

A 67-year-old man was admitted complaining of a 4-month history of fatigue, limbs oedema and, cutaneous vasculitic non-pruriginous lesions. No fever or anorexia. Cortisol levels were 32,5 mcg/dl (normal range: 5 – 25) and ACTH was <4 pg/ml (normal range: 5 – 49). Dopamine, noradrenaline, and metanephrines levels were normal.

A thoracoabdominal contrast-enhanced CT was performed (Figure 1) and compared to a prior CT brought by the patient (Figure 2):

Axial view shows a left heterogeneous adrenal tumour of 83 x 62 mm that infiltrates the ipsilateral parenchyma and renal hilum vessels producing tumoral thrombosis of the renal vein that extends to the IVC. Likewise, a thrombus is observed in the left gonadal vein, ending in the ipsilateral renal vein adjacent to the tumour.

Coronal multiplanar reconstructions of the abdomen show a thrombus along the left adrenal vein and left gonadal vein whose calibres are reactively increased.

Adrenal veins are difficult to identify in normal patients. We take advantage of this case where adrenal veins are pathological to review their anatomy.

Background

Around the fourth week of gestation, a group of mesonephric mesenchymal cells separates from the urogenital ridge of the mesoderm. On both sides, they migrate towards the retroperitoneum forming the primitive adrenal glands [1]. Concurrently, the fetal venous system begins its development by the growth and fusion of capillaries, giving form to 4 main blood drains (paired anterior and posterior cardinal veins) [2]. As organogenesis continues, the inferior vena cava (IVC) formation begins by redirecting flow exclusively medially, and subsequently, posterior cardinal veins regress. The caudal part of these remnants is preserved respectively as the right and left adrenal veins.

Clinical Perspective and Imaging

The left adrenal vein is longer and commonly goes downward inferomedially and posterior to the pancreas, draining into the left renal vein after receiving the inferior phrenic vein [2,3]. The right adrenal vein is shorter and goes directly into the posterolateral wall of the IVC [2,3] (Fig. 3). Anatomical variants are more frequently reported on the right side [3].

Adrenocortical carcinoma (ACC) is a rare tumour (1-2 cases per million) [4], usually diagnosed as incidental but can also be symptomatic (hypertension or hormone imbalance). Although ultrasonography is the first technique performed, contrast-enhanced CT shows higher sensitivity and specificity. CT findings include a large, solid, unilateral mass with invasive margins containing haemorrhagic, cystic, and calcified areas. Enhancement varies depending on the degree of necrosis and haemorrhage. The tumour may progress invading the renal vein and IVC, adjacent renal parenchyma and metastases to lung, liver, or nodes [4]. Final diagnosis was reached by anatomopathological study of a biopsy.

Due to this behaviour, it is important to look at the draining veins to rule out thrombosis. Special attention must be paid because a similar appearance of the thrombus in the adrenal veins may be seen on CT if a too early portal vein phase is acquired due to the mixing effect of the venous return. When this occurs, a delayed acquisition is recommended to confirm a true thrombosis.

Teaching points

Adrenal veins collect the gland’s drainage and act as a pathway for tumoral invasion in ACC. Therefore, adrenal veins must be carefully assessed in the staging of ACC, as well as IVC, left renal and gonadal veins. This is going to be crucial for an effective surgical approach and a better prognosis.