Adrenal incidentalomas: should we be doing PET scans?
Nisha Kaimal, Simon Taggart, Harry Mamtora, Stephanie Soteriadou, Helen Doran & Annice Mukherjee
A 60-year-old man underwent investigations for weight loss and abdominal pain. A CT thorax/abdomen revealed a 2 cm right adrenal nodule, 3 nodules in the left adrenal all <1.4 cm and a 5 mm lung nodule in the right middle lobe. The single phase CT was unable to characterize the adrenal lesions. MRI adrenal showed solid mixed signal pattern in the nodules with signal drop off in opposed phase series consistent with adenomata. Twenty-four hour urine catecholamines, cortisol, DHEAS and renin aldosterone levels were normal. GI investigations demonstrated no cause for weight loss. Repeat CT after 6 months showed stable appearances of lungs and adrenals. Adrenal CT at 14 months from initial scan showed an increase in size of 0.5 cm in the right and 0.3 cm in the left adrenal nodules, considered marginal. Four months later the patient presented with chest pain. A chest X-ray demonstrated a new left lung lesion. Staging CT suggested a new left upper lobe lung carcinoma with mediastinal lymphadenopathy. Endobronchial ultrasound guided FNA of an enlarged mediastinal lymph node confirmed a squamous cell lung cancer. Both adrenal glands showed high avidity to FDG on PET-CT imaging. The patient is currently undergoing palliative chemotherapy.
Discussion: This patient developed a new lung cancer after follow-up of presumed benign adrenal incidentalomata. The lung cancer was not visible on initial or early follow-up imaging.
The prevalence of malignancy in adrenal incidentalomas is <5%. In view of the patients symptoms and multiple adrenal nodules an underlying malignancy was initially sought but not found, however PET was not performed at that stage. An earlier PET scan may have expedited the diagnosis of malignancy in this case. The utility, indication and timing of PET scanning in the evaluation of adrenal nodules are pertinent issues raised by this case.