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E1994. Imaging in Adrenal Gland Pathologies
Authors
  1. Yashant Aswani; UT Health Science Center at San Antonio
  2. Vijayanadh Ojili; UT Health Science Center at San Antonio
  3. Shehbaz Ansari; Seth GS Medical College and KEM Hospital
Background
The Adrenal gland is affected by a myriad of lesions, ranging from a simple cyst to malignant neoplasms. The most common pathology, however, to affect adrenal gland is an incidentaloma (a lesion without an apparent symptom). The ever-increasing use of imaging modalities has led to more frequent detection of such incidentalomas. Certain imaging characteristic favours a benign cause over an aggressive variety of incidentaloma. A simplified approach has been proposed in the presentation using such characteristics in mind. It is, however, not uncommon for an adrenal lesion to present because of the effects of its secretion. The role of imaging in such cases is predominantly to determine extent and distant metastasis as the diagnosis is predominantly biochemical.

Educational Goals / Teaching Points
1. Characterization of an incidental adrenal lesion (incidentaloma) with no underlying malignancy 2. Detection of an adrenal lesion with known biochemical abnormality or primary neoplasm 3. Molecular characterization of pheochromocytomas to guide therapeutic radionucleides

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The most important role of imaging in case of an adrenal incidentaloma is to differentiate between a benign adenoma from the malignant. The frequent occurrence of adrenal adenomas can create a dilemma in patients with a known primary cancer and an adrenal lesion. The characterization of the adrenal lesion in such case as adenoma rather than metastasis can change the principle of management from palliative to curative.Presence of intracellular fat is known to be associated with adrenal adenoma rather than adrenocortical carcinoma or malignancy. This can be detected using various imaging techniques, like attenuation value on unenhanced Computed Tomography, washout criterias and in phase/ out phase imaging. Absence of growth for a long time also suggests benignity. Pheochromocytoma and metastasis from certain primaries, like hepatocellular carcinoma and renal cell carcinoma are known to follow washout criteria for adrenal adenoma. Clinical findings, other imaging characteristics and, lastly, histopathology can help reach the diagnosis in such cases. Apart from tumors, adrenals can also be affected by infection and trauma. Tuberculosis and histoplasmosis are infections known to affect the adrenal gland. Infection and traumatic contusions, in the long run, can cause glandular atrophy, presenting clinically as primary adrenal insufficiency. A benign adrenal pathology, if sufficiently large, may cause pain due to mass effect or may present with significant hemorrhage. Such a lesion are electively removed.

Conclusion
Imaging in adrenal masses can be used for diagnosis or characterisation of a clinically diagnosed adrenal pathology. Clinical history and results of biochemical investigation of the patient is of utmost importance, more than most other branches of radiology. Lastly, adrenal tumors frequently occurs as a component of multitude of syndromes. Hence, detection and characterisation of an adrenal lesion may become the guiding torch for further evaluation.