Introduction: Adrenal medullary hyperplasia (AMH) is a rare syndrome of catecholamine excess.
Case: A 59 year old lady known to suffer from hypertension underwent a computed tomography scan of the abdomen as further investigation for unprovoked deep vein thrombosis. This showed a 37 mm right adrenal mass which enhancedheterogeneously with contrast on the porto-venous phase and became homogenously hyperdense on the delayed phase. Findings were not typical of an adrenal adenoma. The patient was asymptomatic and denied headaches, sweating, palpitations or postural symptoms. Baseline investigations for an adrenal mass including urinary freecortisol, adrenal androgens, aldosterone renin ratio and Chromogranin A were normal. However, she had persistently raised serum noradrenaline levels up to 1120 ng/l (upper limit 420 ng/l). MIBG scan did not show any evidence of phaeochromocytoma and PET CT was negative. MR adrenals confirmed the presence of 2.2×3.3 cm mass but unfortunately, there were no definite features to suggest a specific entity for the cause of the adrenal mass. Thus, the patient underwent right laparoscopic adrenalectomy with adequate pre-operative alpha blockade. Histology confirmed AMH. The adrenal medulla did not exceed 8 mm in size. It stained for Chromogranin A and Synaptophysin. HMB45, S-100 and Ki-67 were negative. The adrenal cortex was unremarkable. Our patient remains clinically well.
Conclusion: AMH is a begin nodular and/or diffuse lesion of the adrenal medulla that is less than 1 cm in maximum diameter. It consists of an increase in the number of chromaffin cells in the adrenal medulla. Lesions larger than 1cm are classified as phaeochromocytomas. AMH can only be diagnosed histologically. AMH is a recognized precursor for phaeochromocytoma in MEN 2 but not in isolated cases. Most AMH cases are picked up during surveillance in patients known to have hereditary PCC. Sporadic AMH is an extremely rare entity.