Adrenal incidentaloma
Adrenal incidentaloma (AI) is an adrenal tumor that is detected by routine physical examination or for reasons unrelated to adrenal disease without obvious clinical symptoms of endocrine abnormalities. Among them, benign non-functional tumors account for about 70%, which do not cause serious consequences and can be followed up and observed.
I. Pathological classification of adrenal incidental tumors
The pathology of adrenal incidental tumors is widely distributed, including adenoma, pheochromocytoma, medullary lipoma, adrenal cyst, cortical adenocarcinoma, metastatic carcinoma, hematoma and other rare tumors. It has been reported that adenoma accounts for 4l%, metastasis for 19%, adrenocortical carcinoma for 10%, medullary lipoma for 9%, pheochromocytoma for 8%, and other rare tumors are usually benign diseases, such as cysts.
Diagnosis
1.Diagnosis of AI should firstly consider the benignity and malignancy of the tumor.
(1)The incidence of malignant tumor is very low in adrenal incidental tumor.
(2) CT examination is the most important: adrenal adenoma is small in size, clear boundary and uniform density; large body, irregular shape, blurred outline, infiltration to the surrounding and increased density generally suggest malignancy.
(3) Tumor density greater than 10-20 Hu, malignancy may be large.
(4) The differentiation between primary and metastatic adrenal malignant tumors is mainly based on two points.
Ⅰ Metastatic tumors are usually seen bilaterally;
Ⅱ metastatic tumors are mostly secondary to other tumors, such as lung cancer, gastric cancer, breast cancer, melanoma, etc.
(5) Adrenocortical carcinoma (ACC) is the most common type of primary malignant tumor of the adrenal gland, accounting for about 14% of AI.
(6) AI with subclinical endocrine function (about 20%):There is a controversy whether to operate on SCCS adenoma. Currently, surgery is considered appropriate for patients with SCCS adenoma in combination with metabolic disease. Episodic Pheo and aldosterone tumors (APA) should be treated surgically because of the risk of hypertensive crisis and cardiac and renal damage from hyperaldosteronism.
2. To determine the tissue type of tumor: cortical tumor, medullary tumor or other types. Pheochromocytoma is the most common type of medullary tumor, while cortical tumors include Cushing’s syndrome, aldosterone tumor, cortical carcinoma, etc.
3. To determine whether the tumor has endocrine function: most of the incidental adrenal tumors have no endocrine function, some cases have low endocrine activity and are subclinical tumors; there are also some cases that usually show as static tumors with no function and endocrine activity, but show endocrine activity during surgery.
(1) Pheochromocytoma: Among the incidental adrenal carcinomas, resting pheochromocytoma is predominant, lacking typical symptoms such as paroxysmal hypertension and headache, palpitations and excessive sweating, which can easily misdiagnose or delay the diagnosis.
(2) Cushing’s syndrome: The diagnostic criteria of Cushing’s syndrome have not been clarified clinically, subclinical autocrine glucocorticoid tumor. Its standard test is the size of dexamethasone inhibition test, small dose dexamethasone test is oral dexamethasone l mg at night, measurement of plasma cortisol at 8 o’clock the next day, if the blood cortisol is less than llO.4 mmo∥L at 8 o’clock in the morning after taking the drug is inhibited. It is the most valuable indicator to determine the diagnosis of cortisolism.
High-dose dexamethasone test is used for the etiological diagnosis of cortisolism, the method is the same as that of low-dose dexamethasone test, except that the dose is increased to 8 mg, and the blood cortisol is suppressed if it drops to less than 50% of the control day. 24h urine free cortisol can reflect the secretion of cortisol more objectively.
(3) Aldosterone tumor: In AI patients with hypertension, the ratio of blood potassium, plasma aldosterone to plasma renin activity (PAC-PRA) should be measured, and the ratio is greater than 30 suggesting an autocrine aldosterone secreting tumor.
Treatment principles
(1) Tumors with diameter ≥4 cm are more likely to develop into functional tumors and should be treated by surgery;
②Surgical treatment should be preferred for adrenal incidental tumors with endocrine function; it is controversial whether to operate for SCCS adenoma. Patients with SCCS adenoma with associated metabolic diseases should undergo surgery
③Young patients, due to the cost of follow-up and disease troubles, surgery;
④Bilateral lesions should be removed on one side first, and the opposite side should be closely followed;
⑤ For tumor diameter <4cm, benign and non-functional, patients can be closely observed if they are older, and follow up with ultrasound and CT examination.
⑥Take a more aggressive surgical attitude to AI of unknown nature.