The adrenal gland

Technical and Interpretive Pitfalls in Adrenal Imaging

The adrenal gland may exhibit a wide variety of pathologic conditions. A number of imaging techniques can be used to characterize these, although it is not always possible to attain a definitive diagnosis radiologically. Incorrect diagnoses may be made if radiologists are not attentive to technical parameters and interpretive factors associated with adrenal gland imaging. Hence, an appreciation of the intricacies of adrenal imaging strategies and characterization is required; this can be aided by understanding the pitfalls of adrenal imaging. Technical pitfalls at CT may relate to the imaging parameters, including region of interest characteristics, tube voltage selection, and the timing of contrast material-enhanced imaging. With MRI, imaging acquisition technique and evaluation of the reference tissues used in chemical shift MRI are important considerations that can directly influence image interpretation. Interpretive errors may occur when evaluating adrenal washout at CT without considering other radiologic features, including the size of adrenal nodules, the presence of fat or calcification, the attenuation of nodules, and atypical imaging features. The characterization of an incidental adrenal lesion as benign or malignant does not end the role of the radiologist; consideration as to whether an adrenal lesion is associated with endocrine dysfunction is required. While imaging may not be optimal for establishing endocrine activity, there are imaging features from which radiologists may infer function. In cases of known endocrine activity, imaging can guide clinical management, including further investigations such as venous sampling. ^©RSNA, 2020.

Calcified Adrenal Lesions: Pattern Recognition Approach on Computed Tomography With Pathologic Correlation

Incidental adrenal lesions are found in 2% to 10% of the population. The presence and pattern of calcifications, in conjunction with other clinical and imaging features, such as soft tissue attenuation, enhancement, and laterality, can aid in narrowing a differential diagnosis, thereby preventing unnecessary biopsies and avoiding delays in management. Calcified adrenal lesions can be categorized under the clinical and laboratory headings of normal adrenal function, hyperfunctioning adrenal tissue, and adrenal insufficiency. In this review, we provide an algorithmic approach to assessing calcified adrenal nodules with correlative radiologic findings.

Practical Approach to Adrenal Imaging

Various pathologies can affect the adrenal gland. Noninvasive cross-sectional imaging is used for evaluating adrenal masses. Accurate diagnosis of adrenal lesions is critical, especially in cancer patients; the presence of adrenal metastasis changes prognosis and treatment. Characterization of adrenal lesions predominantly relies on morphologic and physiologic features to enable correct diagnosis and management. Key diagnostic features to differentiate benign and malignant adrenal lesions include presence/absence of intracytoplasmic lipid, fat cells, hemorrhage, calcification, or necrosis and locoregional and distant disease; enhancement pattern and washout values; and lesion size and stability. This article reviews a spectrum of adrenal pathologies.

Role of Venous Sampling in the Diagnosis of Endocrine Disorders

Venous sampling is the gold standard for localizing abnormal hormone secretion in several endocrine disorders. The most common indication for venous sampling is in the workup of primary aldosteronism, adrenocorticotropic hormone-dependent Cushing's syndrome, and hyperparathyroidism. In experienced hands, venous sampling is safe and accurate. This review discusses the role of venous sampling in the workup of endocrine disease, describing the underlying anatomy and pathophysiology, as an understanding of these concepts is essential for technical and clinical success.

Collision and composite tumors; radiologic and pathologic correlation

The terms composite and collision tumors have been used interchangeably throughout radiological literature. Both composite and collision tumors involve two morphologically and immunohistochemically distinct neoplasms coexisting within a single organ. However, collision tumors lack the histological cellular intermingling seen in composite tumors. Composite tumors often arise from a common driver mutation that induces a divergent histology from a common neoplastic source while collision tumors may arise from coincidental neoplastic change. The purpose of this review is to provide an overview of abdominal composite and collision tumors by discussing hallmark radiographic and pathological presentations of rare hepatic, renal, and adrenal case studies. A better understanding of the presentation of each lesion is imperative for proper recognition, diagnosis, and management of these unique tumor presentations.

Adrenal Imaging

Cross-sectional imaging can make a specific diagnosis in lesions, such as myelolipomas, cysts, and hemorrhage, and is often sufficient to distinguish benign from malignant adrenal processes. CT and MRI are useful studies to identify pheochromocytomas and cortisol-secreting or androgen-secreting tumors. In patients with primary aldosteronism, adrenal venous sampling remains the most accurate localizing study and should be performed in all patients older than 35. Radiolabeled isotope studies serve as second-line diagnostic tests for malignant adrenal tumors, primary or metastatic, as well as for pheochromocytoma. Nuclear imaging studies should follow a robust hormonal diagnosis and be correlated with findings on cross-sectional imaging.

Morphology and ultrastructure of the adrenal gland in Bactrian camels (Camelus bactrianus)

In the present study, we examined the morphological features of the adrenal gland in Bactrian camel by means of digital anatomy, light and electron microscopy. Our findings testified that the gland was divided into three parts, capsule, cortex and medulla from outside to inside as other mammals, and the cortex itself was further distinguished into four zones: zona glomerulosa, zona intermedia, zona fasciculate and zona reticularis. Notably, the zona intermedia could be seen clearly in the glands from females and castrated males, whereas it was not morphologically clear in male. There was a great deal of lipid droplets in the zona fasciculate, while it was fewer in the zona glomerulosa and zona reticularis. The cytoplasm of adrenocortical cell contained rich mitochondria and endoplasmic reticulum. The adrenal medulla was well-developed with two separations of external and internal zones. The most obvious histological property of adrenal medulla cells were that they contained a huge number of electron-dense granules enveloped by the membrane, and so medulla cells could be divided into norepinephrine cells and epinephrine cells. Moreover, the cortical cuffs were frequently present in adrenal gland. Results of this study provides a theoretical basis necessary for ongoing investigations on Bactrian camels and their good adaptability in arid and semi-arid circumstances.

Practical Approach to Adrenal Imaging

Various pathologies can affect the adrenal gland. Noninvasive cross-sectional imaging is used for evaluating adrenal masses. Accurate diagnosis of adrenal lesions is critical, especially in cancer patients; the presence of adrenal metastasis changes prognosis and treatment. Characterization of adrenal lesions predominantly relies on morphologic and physiologic features to enable correct diagnosis and management. Key diagnostic features to differentiate benign and malignant adrenal lesions include presence/absence of intracytoplasmic lipid, fat cells, hemorrhage, calcification, or necrosis and locoregional and distant disease; enhancement pattern and washout values; and lesion size and stability. This article reviews a spectrum of adrenal pathologies.

Adrenal imaging for adenoma characterization: imaging features, diagnostic accuracies and differential diagnoses

Adrenocortical adenoma is the most common adrenal tumour. This lesion is frequently encountered on cross-sectional imaging that has been performed for unrelated reasons. Adrenal adenoma manifests various imaging features on CT, MRI and positron emission tomography/CT. The learning objectives of this review are to describe the imaging findings of adrenocortical adenoma, to compare the sensitivities of different imaging modalities for adenoma characterization and to introduce differential diagnoses.

Adrenal Vein Sampling for Conn's Syndrome: Diagnosis and Clinical Outcomes

Adrenal vein sampling (AVS) is the gold standard test to determine unilateral causes of primary aldosteronism (PA). We have retrospectively characterized our experience with AVS including concordance of AVS results and imaging, and describe the approach for the PA patient in whom bilateral AVS is unsuccessful. We reviewed the medical records of 85 patients with PA and compared patients who were treated medically and surgically on pre-procedure presentation and post-treatment outcomes, and evaluated how technically unsuccessful AVS results were used in further patient management. Out of the 92 AVS performed in 85 patients, AVS was technically successful bilaterally in 58 (63%) of cases. Either unsuccessful AVS prompted a repeat AVS, or results from the contralateral side and from CT imaging were used to guide further therapy. Patients who were managed surgically with adrenalectomy had higher initial blood pressure and lower potassium levels compared with patients who were managed medically. Adrenalectomy results in significantly decreased blood pressure and normalization of potassium levels. AVS can identify surgically curable causes of PA, but can be technically challenging. When one adrenal vein fails to be cannulated, results from the contralateral vein can be useful in conjunction with imaging and clinical findings to suggest further management.

Adrenal disorders in pregnancy

Adrenal disorders may manifest during pregnancy de novo, or before pregnancy undiagnosed or diagnosed and treated. Adrenal disorders may present as hormonal hypofunction or hyperfunction, or with mass effects or other nonendocrine effects. Pregnancy presents special problems in the evaluation of the hypothalamic-pituitary-adrenal axis in addition to the usual considerations. The renin-angiotensin-aldosterone axis undergoes major changes during pregnancy. Nevertheless, the common adrenal disorders are associated with morbidity during pregnancy and their management is more complicated. A high index of suspicion must be maintained for these disorders lest they go unrecognized and untreated.

Adrenal mass imaging with multidetector CT: pathologic conditions, pearls, and pitfalls

The adrenal gland is involved by a range of neoplasms, including primary and metastatic malignant tumors; however, the most common tumor detected is the incidental benign adenoma. Although computed tomographic (CT) findings will not always yield a definitive diagnosis, attention to these findings provides a road map to guide image interpretation. Adenomas typically demonstrate rapid washout, which is defined as an absolute percentage washout (APW) of more than 60% and a relative percentage washout (RPW) of more than 40% on delayed images. Adrenocortical carcinoma typically has an RPW of less than 40%; however, large size and heterogeneity are more reliable indicators of the diagnosis than are washout values. Washout characteristics of pheochromocytoma are variable; in conjunction with high levels of dynamic enhancement, pheochromocytomas may mimic adenoma (ie, APW > 60%, RPW > 40%). Myelolipomas appear as well-defined masses with variable quantities of fat and soft tissue. After contrast material administration, metastases usually demonstrate slower washout on delayed images (APW < 60%, RPW < 40%) than do adenomas, although hypervascular metastases may enhance similarly to pheochromocytoma. Finally, a number of nonadrenal pathologic conditions have been reported to mimic adrenal masses at CT.

The Current Role of Venous Sampling in the Localization of Endocrine Disease

Endocrine venous sampling plays a specific role in the diagnosis of endocrine disorders. In this article, we cover inferior petrosal sinus sampling, selective parathyroid venous sampling, hepatic venous sampling with arterial stimulation, adrenal venous sampling, and ovarian venous sampling. We review their indications and the scientific evidence justifying these indications in the diagnosis and management of Cushing's syndrome, hyperparathyroidism, pancreatic endocrine tumors, Conn's syndrome, primary hyperaldosteronism, pheochromocytomas, and androgen-secreting ovarian tumors. For each sampling technique, we compare its diagnostic accuracy with that of other imaging techniques and, where possible, look at how it impacts patient management. Finally, we incorporate venous sampling into diagnostic algorithms used at our institution.

Adrenal Vein Sampling: How to Make It Quick, Easy, and Successful

Adrenal vein sampling has a reputation as a difficult procedure. However, it is being performed more frequently at some institutions due to the realization that primary aldosteronism is more common than previously believed. At the author's institution, adrenal vein sampling with computed tomographic (CT) and laboratory correlation has been performed more than 800 times in the past 10 years. Adrenal vein sampling is used to determine whether autonomous hormone production is unilateral or bilateral; unilateral secretion can be treated with surgery. The venous drainage of each adrenal gland is predominantly via a central vein. Recognition of the right adrenal vein is the crux of adrenal vein sampling. CT is useful in planning adrenal vein sampling by demonstrating the anatomy and positions of the adrenal veins. A small amount of contrast material is injected gently and slowly into the adrenal vein; it is not necessary to perform formal venography to outline the entire gland. To confirm that the vein is draining the majority of adrenal cortical blood, the adrenal vein sample should have a significantly higher level of cortisol than a peripheral sample. Adrenal glands that are producing aldosterone demonstrate an aldosterone-cortisol ratio that is higher than the peripheral value.

The endocrinology of adrenal tuberculosis: the effects of tuberculosis on the hypothalamo-pituitary-adrenal axis and adrenocortical function

Tuberculosis may affect many of the endocrine glands including the hypothalamus, pituitary, thyroid and adrenals. The most commonly involved endocrine organ in tuberculosis is the adrenal gland. Adrenal glands may be directly or indirectly affected by tuberculosis. Tuberculous Addison's disease is still an important cause of primary adrenocortical insufficiency particularly in the developing countries. Recent improvements in imaging techniques and modern endocrinological tests for the investigation of adrenal function have given us greater insight into the endocrinology of adrenal tuberculosis. Hypothalamo-pituitary-adrenal (HPA) axis is also involved in tuberculosis and recent findings revealed that HPA axis is activated rather than underactivated in active pulmonary tuberculosis. Activated HPA axis in tuberculosis causes increased cortisol secretion which results in a shift in the Th1/Th2 balance towards Th2. T cell dysfunction due to high cortisol and low DHEAS levels may be responsible for immunologically-mediated tissue damage in tuberculosis. In this review, recent findings concerning the adrenocortical function, radiological changes in adrenal glands and HPA axis involvement in tuberculosis are discussed.

Is ovarian and adrenal venous catheterization and sampling helpful in the investigation of hyperandrogenic women?

OBJECTIVE

To audit our practice of performing ovarian and adrenal venous catheterization and sampling in hyperandrogenic women who fail to suppress their elevated androgen levels following a 48-h low-dose dexamethasone suppression test (LDDST). We considered the technical success rate of catheterization, the extra information obtained in addition to the standard biochemical tests and imaging findings, and the impact of sampling on management decisions.

DESIGN

A retrospective analysis of the results of all ovarian and adrenal venous catheterizations performed at St Bartholomew's Hospital, London, in the years 1980-1996.

PATIENTS AND METHODS

Baseline ovarian and adrenal androgens were measured in all women presenting with symptoms and signs of hyperandrogenism. Those patients who failed to suppress their elevated testosterone (T), androstenedione (A4) and/or dehydroepiandrosterone-sulphate (DHEAS) levels following a LDDST to within the normal range or to less than 50% of the baseline value were investigated further with adrenal computed tomography (CT), ovarian ultrasound, and ovarian and adrenal venous catheterization and sampling.

RESULTS

Results were available in 38 patients. The overall catheterization success rate was: all four veins in 27%, three veins in 65%, two veins in 87%. The success rate for each individual vein was: right adrenal vein (RAV) 50%, right ovarian vein (ROV) 42%, left adrenal vein (LAV) 87% and left ovarian vein (LOV) 73%. Eight patients were found to have tumours by means of imaging (adrenal CT and ovarian ultrasound), three adrenal and five ovarian, seven of which underwent operation. In six of these patients the clinical presentation was suggestive of the presence of a tumour; in addition, the combination of imaging findings allowed the detection of suspicious adrenal and ovarian masses in all eight cases. The five patients with ovarian tumours had serum testosterone levels > 4.5 nmol/l. In a further eight patients, laparotomy was performed based on a combination of diagnostic and therapeutic indications; in two of these patients the catheterization results were suggestive of an ovarian tumour. All these eight patients were shown histologically to have polycystic ovarian syndrome (PCOS), and no occult ovarian tumour was identified. None of the patients with nontumourous hyperandrogenism had a baseline testosterone level in excess of 7 nmol/l (median 4.4 nmol/l, range 2.5-7 nmol/l).

CONCLUSIONS

Our results suggest that ovarian and adrenal venous catheterization and sampling should not be performed routinely in women presenting with symptoms and signs of hyperandrogenism, even if they fail to suppress their elevated androgen levels to a formal 48-h LDDST. All patients presenting with symptoms and signs of hyperandrogenism and elevated androgen levels, and where the suspicion of an androgen-secreting tumour is high, should have adrenal CT and ovarian ultrasound imaging to detect such a tumour. Venous catheterization and sampling should be reserved for patients in whom uncertainty remains, as the presence of a small ovarian tumour cannot be excluded on biochemical and imaging studies used in this series alone. Its use should be restricted to units with expertise in this area.

The natural history of incidentally discovered adrenocortical adenomas: a retrospective evaluation

Adrenal adenoma is the most frequent lesion among adrenal incidentalomas. The present retrospective study was undertaken to investigate medium-term evolution of supposed or ascertained adrenocortical adenomas in a group of 53 subjects (16 males and 37 females, aged 31-83 yr), with bilateral (no.=8) or monolateral (no.=45) incidentally discovered adrenal masses (size 10-50 mm, median 25 mm), who were followed-up for 6-78 months (median 24 months). Diagnosis of adenoma was based on size and morphovolumetric aspect of the lesion at computed tomography (CT), scintigraphic pattern using NP59 as a tracer, and it was histologically confirmed in 7 patients. After an extensive hormonal investigation including morning (no.=53) and midnight (no.=28) serum cortisol, plasma ACTH (no.=50), serum DHEAS (no.=51), daily urinary free cortisol excretion (no.=52), post-dexamethasone (1 mg) cortisol (no.=42) and ACTH stimulation test for 17-hydroxyprogesterone (17-OHP) response (no.=48) at the time of diagnosis, patients were periodically re-evaluated for hormonal function and radiological aspect of the lesion(s) by CT. Seven patients underwent surgery 6-42 months after incidentaloma demonstration, with histological diagnosis of adrenal adenoma. During follow-up an increase in the size of the lesion was demonstrated in 22 patients (41.5%); the increase was greater than 10 mm in 8 cases. In 3 patients with unilateral mass, a contralateral lesion appeared 10-52 months after first demonstration. Six patients (11.3%) showed reduction or disappearance of the lesions. On the basis of the hormonal evaluation 3 patients were considered to have subclinical Cushing's syndrome and 10 patients exhibited 17-OHP hyperresponse to ACTH test consistent with partial 21 -hydroxylase deficiency. A significant difference in the size of the lesions was observed between patients with or without 17-OHP hyperresponse to ACTH test (31.1 1.9 vs 24.1 +/- 1.2 mm; p<0.01). No significant changes in the hormonal parameters were observed in the patients, when retested. In conclusion, although none of the patients of the present series exhibited evolution to hypersecretion or to aberrant growth, in more than 40% of patients an increase in the size of the mass was observed, even after a long period of "quiescence". This suggests that a radiological re-evaluation of lesions should be periodically undertaken.

Concurrent secretion of aldosterone and cortisol from an adrenal adenoma - value of MRI in diagnosis

A 43-year-old female with a 24-years history of hypertension presented for further investigation and management of primary hyperaldosternoism. Postural studies were not conclusive and magnetic resonance (MR) imaging demonstrated a 27 x 18 mm lesion of the right adrenal gland which showed no signal loss during in and out of phase imaging. Although these appearances were considered to be atypical of those seen on MR in patients with aldosterone producing adrenal adenomas the patient underwent an adrenalectomy with removal of a 3 x 3 x 2 cm right adrenal mass. Post-operatively she became hypotensive and a 0900 hours serum cortisol was undetectable (< 50 nmol/l), consistent with adrenal insufficiency. Following the administration of hydrocortisone there was normalization of the blood pressure and subsequent adrenal stimulation tests confirmed the presence of functioning adrenal tissue albeit with an inadequate response. Cortisol measurement from preoperative samples revealed loss of normal diurnal rhythm whereas DHEAS levels both pre and postoperatively were undetectable, consistent with ACTH supression resulting from autonomous cortisol secretion in addition to aldosterone. Concurrent secretion of cortisol should always be considered in Conn's adenomas particularly when atypical radiological features are present.

Subclinical Cushing's syndrome in patients with adrenal incidentaloma: clinical and biochemical features

Incidentally discovered adrenal masses are mostly benign, asymptomatic lesions, often arbitrarily considered as nonfunctioning tumors. Recent studies, however, have reported increasing evidence that subtle cortisol production and abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis are more frequent than previously thought. The purpose of this study was to investigate the clinical and hormonal features of patients with incidentally discovered adrenal adenomas, in relation to their clinical outcome. Fifty consecutive patients with incidentally detected adrenal adenomas, selected from a total of 65 cases of adrenal incidentalomas, were prospectively evaluated. All of them underwent abdominal computed tomography scan and hormonal assays of the HPA axis function: circadian rhythm of plasma cortisol and ACTH, urinary cortisol excretion, 17-hydroxyprogesterone, androgens, corticotropin stimulation test and low-dose (2 mg) dexamethasone test. The patients were reevaluated at regular intervals (6, 12, and 24 months) for a median period of 38 months. Subtle hypercortisolism, defined as abnormal response to at least 2 standard tests of the HPA axis function in the absence of clinical signs of Cushing's syndrome (CS), was defined as subclinical CS. Mild-to-severe hypertension was found in 24 of 50 (48%) patients, type-2 diabetes in 12 of 50 (24%), and glucose intolerance in 6 of 50 (12%) patients. Moreover, 18 of 50 patients (36%) were diffusely obese (body mass index, determined as weight/height2, > 25), and 14 patients (28%) had serum lipid concentration abnormalities (cholesterol > or = 6.21 mmol/L, low-density lipoprotein cholesterol > or = 4.14 mmol/L and/or triglycerides > or = 1.8 mmol/L). Compared with a healthy population, bone mineral density Z-score, determined by the DEXA technique, tended to be slightly (but not significantly) lower in patients with adrenal adenoma (-0.41 SD). Endocrine data were compared with 107 sex- and age-matched controls, and patients with adenomas were found to have heterogeneous hormonal abnormalities. In particular, significantly higher serum cortisol values (P < 0.001), lower ACTH concentration (P < 0.05), and impaired cortisol suppression by dexamethasone (P < 0.001) were observed. Moreover, in patients with adenomas, cortisol, 17-OH progesterone, and androstenedione responses to corticotropin were significantly increased (P < 0.001, all), whereas dehydroepiandrosterone sulfate levels were significantly lower at baseline, with blunted response to corticotropin (P < 0.001, both). However, the criteria for subclinical CS were met by 12 of 50 (24%) patients. Of these, 6 (50%) were diffusely obese, 11 (91.6%) had mild-to-severe hypertension, 5 (41.6%) had type-2 diabetes mellitus, and 6 (50%) had abnormal serum lipids. The clinical and hormonal features improved in all patients treated by adrenalectomy, but seemed unchanged in all those who did not undergo surgery (follow-up, 9 to 73 months), except for one, who was previously found as having nonfunctioning adenoma and then revealed to have subclinical CS. In conclusion, an unexpectedly high prevalence of subtle autonomous cortisol secretion, associated with high occurrence of hypertension, diabetes mellitus, elevated lipids, and diffuse obesity, was found in incidentally discovered adrenal adenomas. Although the pathological entity of a subclinical hypercortisolism state remained mostly stable in time during follow-up, hypertension, metabolic disorders, and hormonal abnormalities improved in all patients treated by adrenalectomy. These findings support the hypothesis that clinically silent hypercortisolism is probably not completely asymptomatic.

Addison's disease in Africa--a teaching hospital experience

OBJECTIVE

Addison's disease may present with diverse and non-specific clinical and biochemical features. Contentious issues include the appropriate criteria for the interpretation of the ACTH stimulation test and the necessary extent of investigation to identify a specific aetiology for the hypoadrenalism. The experience of Addison's disease at a South African teaching hospital was reviewed to (1) record the aetiology and spectrum of presentation, (2) examine the performance of the ACTH stimulation test and (3) determine the utility of adrenal CT scan and biopsy.

METHODS

Retrospective study of patients admitted to a South African teaching hospital from 1980 to 1997 with a diagnosis of acute Addison's disease.

PATIENTS AND MEASUREMENTS

Fifty patients presenting with acute Addison's disease were identified by a search of hospital records. Pretreatment biochemical and haematological parameters were recorded. The cortisol response at 20 and 60 min to an intravenous injection of 250 micrograms synacthen (Cortrosyn) was analysed. In a subgroup of affected subjects, the bone mineral density (BMD) in the lumbar spine and femoral neck was measured during long-term follow-up.

RESULTS

Presenting features included hyperpigmentation (86%), weight loss (67%), abdominal pain (20%) and diarrhoea (16%). Thirty-nine patients (78%) were hyponatraemic, while 26 (53%) were hyperkalaemic. Nine patients (18%) were hypoglycaemic and 21% had hypercalcaemia. The mean basal cortisol was 148 nmol/l (range 10-487) and 16 patients (40%) had a normal basal cortisol. The mean cortisol 20 min after ACTH stimulation was 172 nmol/l (range 19-588). There was no significant increase in serum cortisol following ACTH stimulation (P > 0.05). Adrenal CT scans were performed in only 24 patients (48%) and were normal in 10, while abnormalities were detected in 14 patients (bilateral enlargement in 11, calcification in two and atrophic adrenals in one). Eight patients had a DEXA scan performed during follow-up--four were osteopaenic in the lumbar spine and five at the femoral neck. The probable aetiology of Addison's was idiopathic in 42%, related to active TB in 18%, old TB in 16%, autoimmune in 12% and malignancy with metastases in 6%--single cases were due to sarcoid, iron overload and adrenoleukodystrophy. Adrenal biopsy was performed in two patients and was diagnostic of malignancy in both cases. The mortality within the first month after hospitalization was 12%.

CONCLUSIONS

In our experience, Addison's disease is frequently idiopathic, presents with protean manifestations and should be considered in patients with unexplained hyperpigmentation or gastrointestinal complaints, particularly when associated with hyponatraemia and hyperkalaemia. A normal basal cortisol does not exclude the diagnosis which requires ACTH stimulation testing.

Incidentally found adrenocortical carcinoma. A study of 21 patients

The frequency of adrenocortical carcinoma was studied in a group of 311 incidentally discovered adrenal tumours. Clinical characteristics were also analysed. Ultrasound scan and computed tomography were the main imaging techniques used. Hormonal examinations were also carried out. The patients with an adrenal tumour diameter greater than or equal to 4.0 cm, and those with excess steroid production were recommended for surgery. Of 131 patients treated with surgery, adrenocortical carcinoma was diagnosed in 21 cases. The diameter of these tumours ranged between 3.2 and 20.0 cm. The majority of these were hormonally inactive, but, in some cases increased corticosteroid secretion was noted. In 17/21 patients, mitotane was administered following surgery, with a good response in 13 cases. These 21 cases were compared with a group of 51 patients with clinically overt adrenocortical carcinoma.

Subclinical Cushing's syndrome in adrenal incidentaloma

OBJECTIVE

Some patients with incidentally discovered adrenal adenomas display autonomous cortisol secretion not fully restrained by pituitary feedback, a condition that may be defined as subclinical Cushing's syndrome. We have evaluated the presence of subclinical Cushing's syndrome and its natural history in a cohort of patients with incidentally discovered adrenal adenomas.

PATIENTS

Fifty-three consecutive patients (30 women and 23 men; median age 58 years, range 18-81 years) were studied. Diagnostic procedures were initiated for extra-adrenal complaints. Patients with known extra-adrenal malignancies or patients with hypertension of possible endocrine origin were excluded.

MEASUREMENTS

All patients underwent the following endocrine evaluation: (1) measurement of DHEA-S at 0800 h, (2) measurement of serum cortisol at 0800 and 2400 h, (3) measurement of the 24-h excretion of urinary free cortisol (UFC), (4) overnight low-dose dexamethasone suppression test, (5) measurement of plasma ACTH at 0800 h (mean of at least two samples on different days), (6) oCRH stimulation test. Different groups of healthy subjects recruited from the hospital medical staff and their relatives served as controls for the various tests. The same endocrine work-up was repeated after 12 months in 25 patients. All patients were followed up at regular intervals for at least 12 months with clinical examination and abdominal computed tomography. Subclinical hypercortisolism was arbitrarily defined as definitive, probable or possible, according to the degree of endocrine abnormalities.

RESULTS

UFC was significantly higher in patients with incidentaloma than in controls (262, 25-690 nmol/24 h versus 165, 25-772 nmol/24 h; P = 0.012). The percentage of subjects who did not suppress on dexamethasone was greater among patients than among healthy subjects (9/53 (17%) versus 5/103 (5%), P = 0.026). Plasma ACTH concentrations were lower in patients with adrenal incidentaloma than in controls (3, 1-9 pmol/l versus 5, 1-14 pmol/l; P = 0.014). These findings consistently point toward a functional autonomy of the adrenal adenomas even if the degree of cortisol excess is mild. Three patients fulfilled the criteria for definitive subclinical hypercortisolism, five for probable and two possible, but none of them experienced clinical and/or biochemical progression to overt hypercortisolism after 12 months. During follow-up, no signs of extra-adrenal malignancy became manifest and the size of the mass did not increase significantly in any patient.

CONCLUSIONS

This study provides a clear demonstration of the current opinion that some patients with incidentally discovered adrenal adenomas may be exposed to a subtle, silent hypercortisolism. In some patients, in whom the clustering of more abnormalities in the hypothalamo-pituitary-adrenal axis occurs, subclinical Cushing's syndrome could be assumed. This term should be preferred to that of pre-clinical Cushing's syndrome since the biochemical abnormalities do not become clinically manifest, at least in the short term.

Adrenal incidentalomas. Diagnostic workup of the incidentally discovered adrenal mass

The incidentally discovered adrenal mass is a diagnostic dilemma veterinarians are likely to face with increasing frequency in the coming years. Dogs and cats may be more prone to functional adrenal lesions than are humans. Most adrenal tumors are benign, but a significant number of adrenocortical carcinomas (approximately 12%) and metastatic lesions within the adrenal glands (3% to 34%) do occur. Evaluation for hypertension, hypokalemia, and loss of hypothalamic-pituitary-adrenal responsiveness to a low dose of dexamethasone is appropriate for all patients with adrenal incidentalomas. The value of clinical and historical signs of hormonal overexpression should not be underestimated. More invasive or expensive diagnostic testing should be predicted on suspicions raised by the history and clinical signs. New diagnostic clinicopathologic tests, including plasma CgA and serum DHEAS, should be investigated in veterinary patients. Advanced diagnostic imaging using nuclear scintigraphy and chemical-shift MRI may offer veterinarians sensitive and specific noninvasive tools to consider for the evaluation of these patients. Patients with large masses, tumors with signs of malignancy, or productive adrenal tumors (plus or minus cortisol-producing tumors in which chemical ablation with mitotane can be attempted) should be considered candidates for exploratory surgery.

Adrenal changes in murine pulmonary tuberculosis; a clue to pathogenesis?

When mice were infected with virulent Mycobacterium tuberculosis H37Rv by the intra-tracheal route, there was an early phase of adrenal hyperplasia, histologically resembling the adrenocorticotropic (ACTH)-driven changes seen in Cushing's disease. This was followed at 3 weeks by progressive atrophy until the weight of the adrenals was approximately 50% of that seen in control uninfected mice, in spite of the fact that the adrenals were not infected. All layers of the adrenal cortex were affected, but the medulla was normal. Electron microscope studies revealed apoptosis. The switch from adrenal hyperplasia to adrenal atrophy corresponded to onset of an IgG1 response recognising a wide range of mycobacterial components in Western blots. Delayed type hypersensitivity (DTH) responses were seen throughout, but differed in their sensitivity to TNF alpha. Thus if TNF alpha was injected at 24 h into DTH sites elicited during the phase of adrenal hyperplasia, there was no increment in swelling at 48 h. However similar injections of TNF alpha resulted in a doubling of the swelling in DTH sites elicited during the phase of adrenal atrophy. This may be relevant to the pathogenesis of cytokine-mediated tissue damage in the human disease. If 2 months before mice received the intratracheal infection, they were pre-immunised with 1 x 1097) autoclaved Mycobacterium vaccae, a stimulus previously shown to induce a Th1 pattern of response, the early increase in adrenal weight was attenuated and delayed, and the subsequent atrophy did not occur. In sharp contrast, pre-immunisation with 1 x 10(9) autoclaved M. vaccae, known to prime a mixed pattern of cytokine release (IFN gamma and IL-4), resulted in adrenal atrophy that began within 4 days of infection, and was complete by day 14. These results suggested that the pattern of cytokine release provoked by the infection, modulated the adrenal changes, perhaps in synergy with products derived from the organisms themselves. Since we have already shown that profound adrenal changes also occur in human tuberculosis, we now propose that a change somewhere in the cytokine-hypothalamo-pituitary-adrenal axis may underlie the T cell dysfunction and immunologically-mediated tissue damage in this disease.