Thyroid nodules can be classified:
Unique: it is considered a solitary nodule, or only, when a meticulous palpation does not reveal the existence of other thyroid nodules. Its clinical significance lies in the possible existence of thyroid cancer, which occurs in 5% of solitary nodules.If we take into account that more than 50% of the adult population can have a thyroid nodule and the possibility of it being malignant is around 5%, the risk is low.
Multiple: mostly associated with Multinodular Goiter
-By functional activity:
Determined by the analysis of thyroid hormones and the ability to concentrate radioactive iodine in thyroid scintigraphy.
Hypofunctional or cold nodule: (Scintigraphic image of a cold nodule) 80% are benign. Approximate risk of malignancy of 5%, (in the context of multinodular goiter this figure drops to 0,1%).
The cold nodule is characterized by poorly capturing the drug radius, and is seen as a focal lesion in the thyroid gland . In cases of cold nodules aspiration puncture, usually guided by ultrasound, is recommended to rule out or confirm cancer.
Hyperfunctioning (Plummer’s Disease) or Hot Nodule: (Scintigraphic image of a warm nodule) Very low risk of malignancy (<1%), is characterized by taking the radio tracer avidly, with superiority to the rest of the thyroid tissue. This type of nodules have greater activity than the surrounding thyroid, and may or may not be autonomous (does not respond to TSH).
-For its internal structure:
Encapsulated / not encapsulated.
Solid / cystic / with cystic areas.
Type of vascularization (Eco-Doppler):
Peri nodular: the blood vessels are around the nodular capsule giving rise to the “halo sign” (ultrasound finding suggestive of benignity).
Internal vascularization: in this case, the vessels pass through the capsule and continue to proliferate, causing a greater and faster growth of the nodule that requires strict adherence to follow-up
-Etiology or cause:
The most frequent causes of uninodular growth are adenomas, colloid nodules, thyroid cysts and thyroid carcinomas. Other rare causes are subacute thyroiditis, bacterial thyroiditis, thyroid lymphoma, and metastases from other carcinomas. 10-15% of the unique nodules present with hyperthyroidism, being in them the risk of no cancer. In most cases the etiology of thyroid nodules is unknown, even so, we can approximate the following classification according to different causes that can cause them:
Multinodular goiter (colloid adenoma).
Cystic nodule: colloid, simple, hemorrhagic.
Subacute segmental thyroiditis.
Carcinoma of Hürthle cells.
Primary thyroid lymphoma
Metastasis (lung, kidney cells, others).
The diagnosis of thyroid nodules is increasingly frequent, due to the fact that a greater number of neck ultrasounds are performed. According to the report of the ultrasound, it should be decided if a puncture is performed to rule out the presence of malignancy. The BETHESDA System has tried to establish a form of expression of the results of cytological punctures in 6 types, for a better understanding of the results and that in this way the appropriate measures are taken.
The incidence of thyroid nodules is variable, depending on the population analyzed and the method used. The frequency of nodules increases with age, exposure to radiation or in areas with iodine deficiency. In the United States (USA), the incidence of thyroid nodules detected by palpation is 0.1% per year, with a prevalence of 4 to 7% in the general population and 30 to 50% when evaluated by ultrasound or autopsies.
In the presence of a uninodular goiter, when ultrasound is performed, 50% turn out to be multinodular. Of the nodules detected by any method, 5 % will be malignant. The realization of a puncture of the nodule allows to discard in a percentage of the cases, the presence of malignancy.
Thyroid cancer, although rare (it represents between 1 and 2 percent of all cancers), is the most common malignant neoplasm that has its origin in endocrine organs, since it accounts for more than 92 percent of them.
-Fine Needle Aspiration biopsy (FNAB)
According to the protocol that is currently applied, all nodes measuring 10 or more millimeters must be made.
FNAB is the most important test in the study of a thyroid nodule, when the TSH measurement is within normal values, for the method used. This procedure does not require anesthesia since it is usually done with a fine needle (Caliber 21-23) to obtain cellular material that is fixed for cytological study. It generates some discomfort and the level of pain will depend on the threshold of each individual. It is a method: simple, effective with good diagnostic performance and low cost.
The limitations of the method are: 1) the possible need to repeat the puncture if inadequate material is obtained, 2) the impossibility of the method to differentiate malignant and benign follicular lesions (adenoma vs. follicular carcinoma), 3) not having a trained cytologist in the visualization of these images.
The follicular adenoma can not be differentiated by cytological puncture. If follicular cells are obtained in the cytological puncture, therefore, by means of a simple statistical calculation we can establish, 0.02% (2 cases in 10,000 or 1 case in 5,000) that is a cancer.
-The thick needle biopsy (TNB).
Provides specimens susceptible to histological analysis Some comparative studies show greater reliability of the TNB against FNAB.The use of TNB allows to increase the sensitivity of the technique with respect to FNAB It reduces the interoperator variability It is not more complex from a point of view It does not increase complications It is an obvious alternative to non-diagnostic FNAB.
On the other hand, when the nodule is of cystic character it allows its emptying and it can be a therapeutic procedure. This test has a sensitivity of 90 to 95% (ability to diagnose cancer) and specificity of 85% (ability to exclude patients without cancer) in experienced hands.
For many years there have been difficulties in the expression of the results of said cytological study. With the attempt to correct this problem, the National Cancer Institute (NCI) of the USA organized a consensus meeting in 2007 in BETHESDA.
The discussions and conclusions of the same in relation to the terminology and morphological criteria were published later in the atlas “The Bethesda System for Reporting Thyroid Cytopathology”.
The purpose of this meeting was to try to agree on the terminology to be used and that it be used universally. The cytopathologist should send the doctor a clear, concise, and clinically useful report.
In order to better understand the BETHESDA System (SB), it is recommended that each report of thyroid cytopathology have a diagnostic category of the six that have been established:
I) Non-diagnostic or Unsatisfactory
III) Atypia of undetermined meaning or follicular lesion of undetermined meaning
IV) Follicular Neoplasm or Suspect of Follicular Neoplasia
V) Suspect of malignancy
It is also noted that in some of the general categories some degree of sub-categorization can be informed and often necessary, recommending the following terminology:
I. Non-diagnostic or Unsatisfactory
Cystic fluid only
Virtually acellular specimen
Other (darkened by blood, lumpy material, etc.)
Compatible with benign follicular nodule.
Here entities classified histologically as nodular goiter are grouped,
hyperplastic nodule (adenomatoid), colloid nodule, nodules in
Graves Basedow and the macrofollicular subtype of adenomas. It can be used
a more specific term in the clinical context each pathology.
Compatible with lymphocytic thyroiditis (Hashimoto) associated with clinical presentation.
Compatible with granulomatous thyroiditis (subacute).
III. Attypia of indeterminate meaning (AUS) or
Follicle lesion of undetermined significance (FLUS).
The term AUS is reserved for samples containing cells (follicular, lymphoid or other) with architectural and / or nuclear atypia that is not sufficient to be classified as suspicious of follicular neoplasia, suspicious of malignancy or malignancy but is more marked than the attributable to benign changes. The term FLUS is also accepted for most cases in which the atypia is of follicular origin. Its use should not exceed 7% of cytological diagnoses (NCI). Although several works show a greater number that can reach up to 20%, according to the literature consulted
IV. Follicular Neoplasm or Suspect of Follicular Neoplasia
Specify if it is of the Hürthle cell type (oncocytic)
V. Suspect of malignancy
Suspicious for papillary carcinoma
Suspicious for medullary carcinoma
Suspect for carcinoma metastasis
Suspect for lymphoma
VI. malignant one
Poorly differentiated carcinoma
Undifferentiated carcinoma (anaplastic)
Squamous cell carcinoma
Carcinoma with mixed characteristics (specify)
– How the severity of cancer is determined:
Cancer is the disorderly growth of abnormal cells in the body. These cells often form a tumor. This tumor can grow into the other tissues and organs that surround it. As the cancer progresses, abnormal tumor cells can spread to other parts of the body either through the bloodstream or the lymphatic system. When the cancer spreads, tumors can form in other organs and parts of the body. This cancer spread is called metastasis.
Cancer staging is used to describe the type of cancer progression. This allows to determine:
The location of the primary (original) tumor and the type of cancer cells
The size of the primary tumor
If the cancer has spread to the lymph nodes
The number of secondary tumors caused by the cancer that has spread
The grade of the tumor (how similar the cancer cells are to normal cells)
To evaluate cancer, different tests can be performed, depending on the location of the body in which the disease is found. These may include:
Imaging tests such as x-rays, CT scans, positron emission tomography (PET) scans, or magnetic resonance imaging
Surgery may also be done to remove the tumor mass and lymph nodes or to explore the extent of lymph node and take a tissue sample. These samples are analyzed and can provide more detailed information about the stage of cancer.
TNM staging system
The most common system for staging cancer in the form of a solid tumor is the TNM system. Most providers and cancer centers use it to stage most cancers. The TNM system is based on:
The size of the primary tumor (T)
How much cancer has spread to nearby lymph nodes (N)
Metastasis (M), that is, if the cancer has spread to other areas of the body and to what extent it has
Numbers are added to each category that explains the size of the tumor and how much it has spread. The higher the number, the larger the size and the more likely the cancer has spread.
-Primary tumor (T):
TX: It is not possible to measure the tumor.
T0: It is not possible to find the tumor.
Tis: Abnormal cells have been found, but these have not spread. This is called carcinoma in situ.
T1, T2, T3, T4: Indicates the size of the primary tumor and how much it has spread to the surrounding tissue.
-Lymph nodes (N):
NX: It is not possible to evaluate the lymph nodes
N0: No cancer was found in nearby lymph nodes
N1, N2, N3: Number and location of involved lymph nodes to which the cancer has spread
MX: It is not possible to evaluate the metastasis
M0: No metastasis was found (the cancer has not spread)
M1: Metastasis was found (the cancer has spread to other parts of the body)
For example, a prostate cancer T3 N0 M0 means that there is a large tumor (T3) that has not spread to the lymph nodes (N0) or to any other part of the body (M0).
Sometimes other letters and subcategories are used in addition to those mentioned above.
The grade of a tumor, such as G1-G4 can also be used in conjunction with staging. This describes how similar the cancer cells are to normal cells when they are analyzed under a microscope. Higher numbers indicate abnormal cells. The less cancer looks like normal cells, the faster it will grow and spread.
Not all cancers are staged using the TNM system. This is because some cancers, especially cancers of the blood and bone marrow such as leukemia, do not form solid tumors or spread in the same way. Therefore, other systems are used to stage these cancers.
-Determination of stage:
Based on TNM values and other factors, a stage is assigned to your cancer. The different cancers are staged in different ways. For example, stage III pancreatic cancer is not the same as stage III breast cancer. In general, a higher stage refers to a more advanced cancer.
Stage 0: Abnormal cells are present, but these have not spread
Stages I, II, III: These refer to the size of the tumor and how much the cancer has spread to the lymph nodes
Stage IV: The disease has spread to other organs and tissues
Once a stage has been assigned to your cancer, it does not change, even if the cancer returns over time. The stage of a cancer is based on what was found when it was diagnosed.
The most commonly used staging system for thyroid cancer is the TNM system of the American Joint Committee on Cancer (AJCC), which is based on three key pieces of information:
It takes into account the size of the tumor (T), and if it has spread nearby structures.
Propagation to adjacent lymph nodes (nodes) (N): If the cancer has spread to adjacent lymph nodes.
Propagation (metastasis) to distant sites (M): If the cancer has spread to distant organs such as the lungs or the liver.
The systems described below are the most recent AJCC systems, effective since January 2018, and apply to differentiated, anaplastic and medullary thyroid cancers.
The numbers and letters after the T, N and M provide more details about each of these factors. The higher numbers mean that the cancer is more advanced. Once a patient’s T, N, and M categories have been determined, this information is combined in a process called a stepwise grouping to designate a general stage.