الفهرس 
Pathology of Incidentalomas in the Affected OrgansOnly 14 pages are availabe for public view
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Abstract
An incidentaloma is a tumor found by coincidence usually during imaging performed for unrelated reasons. The most common types of incidentalomas found are adrenal, thyroid, pituitary, parathyroid and pancreatic incidentalomas. When an incidentaloma is found further diagnostic procedures should be completed to determine the nature of the incidentaloma to identify the treatment of choice for each one.
A search for hormonal hypersecretion is the first critical issue to address in adrenal incidentaloma. LDDST, measurement of fractionated metanephrines and catecholamines in a 24h urinary specimen and measurement of plasma aldosterone and renin levels are used to diagnose subclinical Cushing’s syndrome, pheochromocytoma and primary hyperaldosteronism respectively.
Surgery should be performed in all adrenal incidentalomas that fulfill particular criteria in terms of size, function and mass development on imaging follow up.
In patients with subclinical Cushing’s syndrome surgical resection should be reserved for those with worsening of hypertension, abnormal glucose tolerance, dyslipidemia, or osteoporosis. After adrenalectomy, patients should be treated with exogenous glucocorticoids. Surgical resection should be performed for all pheochromocytomas, primary aldosteronism with a unilateral source of aldosterone excess and if adrenocortical carcinoma is suspected.
For pheochromocytomas not suitable for surgery, alternative therapeutic options are recommended, in particular, adrenergic receptor blockers and calcium channel antagonists. In primary aldosteronism, lifelong medical treatment with aldosterone-receptor antagonist should be considered as an alternative to surgery.
In adrenocortical carcinoma, when surgery is insufficient or in the case of stage III and IV disease or recurrent disease, mitotane appears to be the most helpful regimen, alone or in combination with cytotoxic chemotherapy.
Alternative therapeutic options are radiotherapy and percutaneous chemical ablation under CT guidance. Anti-angiogenic agents, tyrosine kinase inhibitors, gene therapy and immunotherapy comprise new modalities that may improve future treatment.
To assess if a thyroid incidentaloma is autonomously functioning, TSH level should be drawn as the first step. Then diagnosis should be confirmed by free T4 and free T3 levels. Ultrasound is excellent in the evaluation of thyroid nodules, distinguishing solid from cystic ones and guide FNAB. FDG-PET/CT provides the advantages of two modalities; the anatomic information is provided by the spiral CT and the functional information by the FDG-PET.
Management of patients with thyroid incidentaloma depends largely on the results of FNAC. Surgery is indicated for symptomatic benign thyroid nodules, follicular thyroid neoplasms, suspicious or malignant nodules.
The surgical approach should be planned according to the clinical setting and imaging findings. Minimally invasive procedures such as percutaneous ethanol injection and thermal ablation may be used in selected cases. Non surgical treatment includes radioiodine therapy (with or without rhTSH) and levothyroxine suppressive therapy.
The initial evaluation of a patient with a pituitary incidentaloma includes laboratory screening for hormone hypersecretion in all incidentaloma patients and screening for hypopituitarism in patients with macro-incidentalomas but not in all patients with micro-incidentalomas.
Pituitary tumors are best imaged with MRI. Inferior petrosal sinus sampling for ACTH before and after CRH injection has been helpful in identifying pituitary tumors and has a sensitivity approaching 100%.
Patients with pituitary incidentalomas are referred for surgery: if they have a visual field deficit, if the lesion abuts the optic nerve or optic chiasma, if they have pituitary apoplexy, or if they are found to have a hypersecreting tumor other than a prolactinoma.
The primary goal of dopamine agonists in patients with microprolactinomas is to restore gonadal and sexual function by normalizing prolactin levels, but in patients with macroadenomas, control and reduction of tumor size are also important. The medical treatment of Thyrotropin-secreting pituitary adenomas mainly rests on the administration of somatostatin analogues such as octreotide and lanreotide.
Intraoperative and postoperative measurements of serum calcium and PTH along with postoperative bone density testing can help determine whether such parathyroid incidentalomas are functional or not.
Indications for surgery include calcium levels more than 1 mg/dl above the upper limits of normal, younger (<50 years) patients, osteoporosis and a creatinine clearance of <60 ml/min. Incidentally identified enlarged parathyroid glands during surgery should be removed. In patients with parathyroid carcinoma, the optimal surgical treatment is en bloc resection with ipsilateral thyroid lobectomy and removal of any enlarged or abnormal lymph nodes. Surgery is the only curative treatment.
There are six criteria for the diagnosis of insulinomas: documented blood glucose levels ≤ 40 mg/dl, concomitant insulin levels ≥ 6 μU/ml, C-peptide levels ≥ 200 pmol/l, proinsulin levels ≥ 5 pmol/l, ß-hydroxybutyrate levels ≤ 2.7 mmol/l and absence of sulfonylurea in the plasma and/or urine. For gastrinomas, two measurements are critical: Fasting Serum Gastrin (FSG) and Basal Gastric Acid Output.
Pancreatoscopy is a modality that may prove to be useful in diagnosis patients with certain pathologic processes. MRCP is superior to multidetector CT for characterization of IPMN. Endoscopic ultrasonography and fine needle (FNA) sampling have revolutionized the diagnosis and treatment of pancreatic lesions.
Solid pancreatic tumors generally require resection. Resection including lymph node dissection is recommended for all MD-IPMN and MCN in reasonable surgical candidates. Resection is also recommended for Br-IPMN that is symptomatic, > 3 cm, have mural nodules or demonstrate cyst-aspirate cytology which is positive for malignancy. Radical surgery is the cornerstone of the treatment of primitive NETs and GISTs.
Medical treatment of gastrinomas is based on the use of proton pump inhibitors at an appropriate dosage. Insulinomas are treated with diazoxide associated with hydrochlorothiazide. For other well differentiated cancers therapy is based on the use of SSAs, interferon and targeted therapy.
Pancreatic NETs can over express some molecules such as EGFR, VEGF, VEGFR or IGFR that can be targeted by some new drugs under assessment in early clinical trials. Another therapeutic approach is PRRT, which uses somatostatin analogues to convey radioactivity within the tumor itself.