INCIDENTALLY DISCOVERED ADRENAL MASSES

Incidental and metastatic adrenal masses

In the last decades discoveries of adrenal masses incidentally during the course of diagnostic procedures for unrelated disorders (incidentalomas) have become progressively more frequent. The clinician in this position must answer two main questions: Is the mass benign or malignant?, and To what extent is the adrenal secretion altered? To come to a clinical decision, several diagnostic tools need to be engaged, starting with an accurate and correct radiological evaluation and a hormonal assessment of the adrenal function. When necessary, other diagnostic procedures such as functional imaging and fine-needle biopsy (FNB) can be considered in selected cases. Surgical removal is recommended for clinically relevant hypersecretory masses, as well as for masses suspected to be malignant. Most frequently, adrenal incidentalomas (AIs) are represented by benign cortical adenomas, a subset of which causes a mild hypercortisolism, known as subclinical Cushing's syndrome (SCS). The criteria to define this syndrome, as well as its treatment, are still debated and controversial. AIs that are not surgically removed should be re-examined in time to exclude a supervening increase in size or function. Follow-up criteria have not been established. Laparoscopic surgery is the recommended procedure to remove benign masses. The surgical procedure for adrenal malignancies is still debated.

MR imaging of the adrenal glands

MR imaging is used commonly for imaging the adrenal glands. Its high-contrast resolution and multiplanar imaging capability enables the detection and characterization of many adrenal masses. The advent of chemical-shift imaging revolutionized the role of MR imaging in characterizing adrenal masses. In this article, the authors discuss the range of MR appearances of common and uncommon adrenal masses, focusing on the nonfunctioning incidentally discovered mass and its characterization methods. MR imaging is continuously improving. The increasing use of higher strength magnets and the introduction of newer coils, sequences, and techniques will help detect and characterize very small adrenal masses, quantify their fat content, and provide exquisite morphologic images of the gland and its vascular supply.

[Contribution of the scintigraphy with iodocholesterol (I-COL) to the diagnosis and characterization of silent adrenal masses]

OBJECTIVE

To assess the role of the adrenal cortical scintigraphy with 131-I Norcholesterol (I-COL) in the diagnosis and characterization of silent adrenal masses.

METHODS

We selected 57 patients who underwent an adrenal scintigraphy with I-COL, 36 women and 21 men (mean aged: 62.5 years), and who were classified into two groups: Group I or Incidentalomas, 39 patients without signs or symptoms of adrenal disease in whom an adrenal mass is incidentally discovered during a CT or ultrasound scan; and a second group or Group II, 18 patients with history of cancer in whom an adrenal mass is discovered. We defined the following Scintigraphic patterns in relationship with the CT: Normal, concordant unilateral (CU) or exclusive; discordant unilateral (DU); concordant asymmetrical (CA) or prevalent; discordant asymmetrical (DA) and nonvisualization (NV). The final diagnosis was obtained with clinical, analytical, and radiological evaluation and in some cases surgery.

RESULTS

In Group I, the diagnoses were: 17 adrenal masses without criteria of malignancy or hormonal overproduction (the Scintigraphic patterns were 10 CA, 5 normal and 2 CU), 9 Subclinical Cushing's syndrome (4 CU, 4 CA and 1 normal), 5 adenomas (all CU), 3 adrenal primary carcinomas, with no uptake in the scintigraphy, and 5 were other diagnoses. In group II, 14 patients had benign masses (all patterns were normal or concordant) and 4 patients metastases (3 discordant and 1 NV patterns). The follow-up time was at least one year.

CONCLUSIONS

The adrenal cortical scintigraphy with I-COL provides us information on the functional status of silent adrenal masses and it is an useful tool to distinguish benign from malignant lesions; for this reason we considered that it must be integrated in the diagnostic algorithm as a complement to other techniques.

[Non-secreting adrenal tumours]

This paper presents the clinical features, imaging methods and treatment of non-secreting adrenal tumours. Adrenal incidentalomas are especially discussed. The main histological types of adrenal non-secreting tumours are evoked. Therapeutic considerations are discussed.

Imaging of adrenal masses

Adrenal pathology may be discussed based on hormonal functionality of the adrenals, appearances on imaging modality, or pathological determination. There are three main categories of adrenal function. Hyperfunctional states include Conn's or Cushing's syndrome. Lesions with normal function may be detected incidentally. Hypofunctional states may occur from idiopathic Addison's disease or some bilateral adrenal pathology. The most common modalities for characterization of adrenal pathology are non-enhanced CT, often followed by contrast CT or chemical shift MRI. The common appearance on non-enhanced CT is a well-defined homogeneous lesion with low-density due to the microscopic fat present and adrenal adenomas. When density criteria are not met, many of these may be characterized as adenomas by washed out of contrast or signal decrease using in phase and out-of-phase MRI sequences. Other non-invasive modalities may incidentally discover adrenal lesions, but are not typically used in the work-up. NP-59 is an uncommonly used nuclear medicine technique which is very specific for adenoma when correlated with pathology on other imaging studies. In the rare cases where non-invasive imaging is non-specific, fine needle aspiration or core biopsies may be necessary. However, biopsies have associated risks including infection and hemorrhage. The imaging appearance of an adrenal lesion is often specific such that further imaging is not necessary. These lesions include adrenal adenoma, pheochromocytoma, myelolipoma, adrenal cyst, and some large adrenocortical carcinomas. However, the findings in lesions such as metastasis, smaller primary adrenal carcinomas, lymphoma, granulomatous disease, and many adenomas are not as specific. In the proper clinical situation, follow-up imaging may be necessary, or biopsy may be warranted.

Imaging of extrapulmonary tuberculosis

Diagnosis of extrapulmonary tuberculosis is often difficult. Although positive chest radiographic findings or a positive tuberculin skin test supports the diagnosis, negative results do not exclude extrapulmonary tuberculosis. However, recognition and understanding of the radiologic findings of extrapulmonary tuberculosis can help in diagnosis. The spine is the most common site of skeletal involvement. The femur, tibia, and small bones of the hands and feet are most commonly involved by tuberculous osteomyelitis. Tuberculosis of the joints is characteristically monoarticular; the knee and hip are most frequently affected. Central nervous system tuberculosis takes various forms, including meningitis, tuberculoma, abscess, cerebritis, and miliary tuberculosis. Ileocecal involvement is seen in 80%-90% of patients with abdominal tuberculosis. The most common manifestation of abdominal tuberculosis is lymphadenopathy. Genitourinary tuberculosis is the most common manifestation of extrapulmonary tuberculosis. Lymphatic tuberculosis is more common among children, with cervical or supraclavicular nodes most frequently involved. Tuberculosis of the breast is extremely rare and occurs most often in young, multiparous, lactating women. The radiologic features of extrapulmonary tuberculosis mimic those of many diseases. A high level of suspicion is required, especially in high-risk populations. A positive culture or histologic analysis of biopsy specimens is still required in many patients for definitive diagnosis.

Magnetic resonance: evaluation of adrenal lesions

Magnetic resonance imaging provides a detailed display of adrenal anatomy. The development of new imaging sequences, especially chemical shift imaging, has vastly enhanced the specificity of magnetic resonance imaging. This review outlines current magnetic resonance imaging strategies for assessing disease affecting the adrenal glands. Particular emphasis is placed on the characterization of adrenal masses.