im awesome
The endocrine system is composed of multiple glandular organs responsible for complex metabolic regulatory functions.
The principal organs of the endocrine system include the thyroid, pituitary, and adrenal glands.
The master regulatory gland of the endocrine system is the pituitary, which produces many hormones under the influence of the hypothalamus.
The most widely recognized endocrine dysfunction is insufficient insulin production by the islet cells of the pancreas, known as diabetes mellitus.
Although thyroid cancers are the most common of the endocrine malignancies, they only represent 2% of all cancers.
Thyroid cancer has the highest incidence rate of all endocrine system cancers.
Thyroid cancer accounts for approximately 96% of all new cases and 67% of deaths.
External radiation to the thyroid gland, particularly before puberty, is the only well-documented etiologic factor.
Age, gender, histologic subtype, and capsular invasion are prognostic indicators for thyroid cancer.
Patients with well-differentiated (papillary and follicular) thyroid carcinoma have a better prognosis than those with undifferentiated (anaplastic) carcinoma.
The thyroid gland consists of a right and left lobe and lies over the deep structures of the neck.
Hyperthyroidism is hyperactivity of the thyroid gland.
Hypothyroidism is under-activity of the thyroid gland.
The thyroid gland produces iodothyronine and thyroxine, responsible for metabolic regulation.
Graves disease is the leading cause of hyperthyroidism and has no long-term adverse health consequences if the patient receives prompt and proper medical attention.
Goiter disorder is a physical sign of an enlarged thyroid gland caused by overstimulation of TSH.
If goiter disease is associated with increased hormone production, it is referred to as toxic goiter.
Most patients with thyroid cancer have a palpable neck mass, often detected during routine physical exams.
Occult and differentiated thyroid cancers can go undetected for years due to their indolent nature.
Most patients with medullary carcinoma initially have an asymptomatic painless mass, but may later present with systemic symptoms like diarrhea due to vasoactive substances (calcitonin) produced by the tumor.
Anaplastic carcinomas are usually large, hard, fixed, grow rapidly, and occur in older patients, often leading to symptoms related to compression or invasion of the esophagus, airway, or recurrent laryngeal nerves.
Symptoms for anaplastic carcinoma include pain, dysphagia, dyspnea, stridor, and hoarseness.
Clinical presentation cannot determine a diagnosis of carcinoma; a biopsy is crucial for diagnosis.
Lab testing includes analysis of thyroglobulin and calcitonin levels; elevated levels after surgery indicate residual thyroid cancer and can be correlated with iodine-131 imaging for detection of the thyroid cancer.
The four radiopharmaceuticals most commonly used for radionuclide imaging of the thyroid are I-131, I-125, I-123, and technetium-99m (Tc-99m).
Sonography can determine if a nodule is solid or cystic and is used as a complementary test to radionuclide imaging.
CT cannot differentiate between benign or malignant lesions.
Needle aspiration cytology is performed with a small-gauge needle; core needle biopsy with a large cutting biopsy needle.
Malignant thyroid neoplasms are divided into four categories: papillary, follicular, medullary, and anaplastic.
Papillary cancers are the most common types of thyroid cancers and are slow-growing with an excellent prognosis.
Anaplastic carcinoma is the least common and carries the worst overall prognosis, with a typical life expectancy of 1 year or less.
Papillary and mixed carcinomas metastasize to regional lymph nodes early in disease development.
Follicular cancers tend to invade vascular channels and metastasize via bloodstream to distant sites like bone, lung, liver, and brain.
Medullary carcinoma spreads regionally before distant metastases with common sites being cervical nodes, lung, liver, and brain.
Surgical resection of the thyroid gland is performed for papillary carcinoma; initial treatment for medullary carcinoma typically includes total thyroidectomy and central compartment lymph node removal.
Surgery for anaplastic carcinoma is effective in specific conditions; tracheotomy may be necessary to preserve airflow.
Side effects of surgery can include tumor hemorrhage and damage to the parathyroid gland, potentially leading to vocal cord paralysis.
I-131 is used to treat papillary and follicular cancers; papillary and mixed carcinomas are more radiosensitive than follicular carcinomas, while medullary thyroid cancer is less radiosensitive than papillary carcinoma.
Anaplastic carcinomas are not responsive to any treatment.
CT simulation for a patient with thyroid cancer should involve neck extension and careful head immobilization.
The spinal cord is the most important consideration when using IMRT to treat thyroid cancer.
The radiation field for treating thyroid cancer should encompass the entire thyroid gland, neck, and superior mediastinum using 3D treatment planning techniques (IMRT).
Most pituitary tumors are benign adenomas, and the pituitary is composed of anterior, posterior, and intermediate lobes.
The most common hypersecretory tumor type is prolactinoma, followed by growth hormone-secreting adenomas, which can lead to acromegaly in adults and gigantism in children.
The ACTH-secreting adenoma is the third most common functioning pituitary tumor, leading to excess cortisol secretion.
Prognosis for pituitary tumors relies on adenoma type, extent of abnormalities, treatment success in normalizing endocrine activity or relieving pressure, treatment morbidity, and effectiveness in preventing recurrence.
The pituitary gland measures about 1.3 cm in diameter and is located at the brain's base, attached to the hypothalamus by the infundibulum.
Acidophils secrete prolactin and GH, while basophils secrete ACTH, TSH, follicle-stimulating hormone, luteinizing hormone, and melanocyte-stimulating hormone.
Hypersecretion before puberty results in gigantism; hyposecretion after puberty results in acromegaly, characterized by weight gain and physical changes.
Visual acuity and field defects signify tumor extension beyond the sella turcica; the most common visual field defect is bitemporal hemianopsia.
The principal imaging studies for the pituitary gland are CT or MRI, with microadenomas being less than 10mm and macroadenomas greater than 10mm.
No true staging exists for most benign pituitary tumors; the primary treatment goal is normalizing pituitary hormonal function or alleviating local tumor effects.
Pituitary tumors can be treated with surgery, radiation therapy, medically, or a combination of these modalities, with possible surgical complications like CSF leakage (2%).
The transfrontal and transsphenoidal approaches provide direct access to the pituitary gland.
Fractionated SRS is a form of SBRT; surgery and radiation therapy (alone or combined) yield excellent treatment results for pituitary tumors.
Tumors arising in the adrenal glands are classified based on their origin: the outer portion (cortex) and inner portion (medulla).
The cortex produces steroid hormones essential for metabolic regulation, while the medulla produces epinephrine/adrenaline, regulated by the autonomic nervous system.
Adrenocortical tumors are very rare and occur equally in the left and right glands; lymphatics from adrenal glands drain into the paraaortic nodes.
Due to the abdominal location of adrenal cortex tumors, advanced cancer often presents with pain, while lab testing can confirm diagnosis for functioning tumors.
Nonfunctioning tumors may present pain associated with advanced disease, and no true staging system exists for adrenocortical tumors due to their rarity.
Well-differentiated adrenocortical tumors show capsular and vascular invasion and abnormal mitoses.
Adrenocortical carcinomas can invade surrounding tissues and may metastasize to regional nodes and distant sites (lung, liver, brain).
Right-side adrenal cortex tumors often involve the kidney, liver, and vena cava; left-side tumors involve the kidney, pancreas, and diaphragm.
Surgical intervention is the treatment of choice for adrenal cortex tumors, with radiation therapy having a limited role but may adjunctively improve local control or palliate metastatic disease.
The prognosis for patients with adrenal cortex tumors is poor, significantly influenced by stage or diagnosis and resectability.
Adrenal medulla tumors are well-defined, circumscribed, and may range in color and can invade locally or spread to regional lymph nodes/distal organs.
Surgery is the preferred treatment for adrenal medulla tumors, while persistent elevated blood pressure signifies residual tumor or metastatic disease.