A difference of opinion – poor concordance between clinical, biochemical and radiographic findings in a case of an adrenal incidentaloma

TM Galliford and JP Cox

An adrenal incidentaloma is a mass lesion greater than 1 cm in diameter serendipitously discovered by radiologic examination.  Technological advances in computed tomography (CT) and magnetic resonance (MR) imaging is leading to increased prevalence of detection of these tumours.

A 60 year old gentleman was referred to the Endocrine Unit at St. Mary’s Hospital in 2004 with a 2cm adrenal mass which had been detected on abdominal CT.  He was a heavy smoker and had a history of alcohol excess but was now abstinent.  The gentleman complained only of weight loss and numbness in the hands and feet.  There was no history consistent with catecholeamine excess and he was not taking any medication. Blood pressure was 141/73mmHg, and there were no clinical features of Cushing’s syndrome.  A mild peripheral neuropathy was present in both upper and lower limbs.  MR adrenals confirmed the 2cm mass with both adrenal glands having lumpy nodular outlines.  The imaging characteristics of the adrenals were not typical of bilateral adrenal adenomas however and the appearance of the mass was consistent with phaeochromocytoma.

Urine catecholeamines were negative on 5 separate occasions.  Baseline urinary cortisols were mildly elevated at 406 and 361nmol/24 hours.  9am cortisol 419nmol/l, ACTH 8ng/l which did not fully suppress at 48hours on low dose dexamethasone testing (cortisol 79nmol/l). The biochemical diagnosis was therefore sub-clinical Cushing’s syndrome.  Subsequently, annual urinary free cortisols have been both raised and normal, but Cushing’s syndrome has not developed and the adrenal glands remain unchanged on imaging.  The parasthesiae had worsened however.  A peripheral neuropathy screen was unremarkable.  CXR demonstrated overexpanded lung fields and flattened diaphragms and given this and we proceeded to CT chest which has shown a 5mm nodule in the right lung base.  The patient has been referred to the respiratory and neurology teams for further investigation.

This case demonstrates the importance of ensuring that diagnoses are based upon clinical, biochemical and radiographic grounds.  Up to 20% of patients with adrenal incidentalomas have abnormal cortisol production and can be classified as having subclinical Cushing's syndrome. Although overt Cushing's syndrome may not develop, these tumours can be associated with conditions caused by steroid hormone excess such as diabetes.  In the absence of these features however, our case demonstrates that monitoring is permissible, surgery unnecessary and furthermore that associated inexplicable medical complaints such as parasthesia warrant further investigation.