Follicular adenoma thyroid: follicular carcinoma and follicular adenoma

What is the cause of thyroid in follicular adenoma?

Follicular adenoma thyroid are the most common benign tumors, namely benign follicular adenomas. Most occur in women under the age of 40. Because thyroid tumor can cause hyperthyroidism, and there is a certain malignant possibility, it should be removed as soon as possible. Patients often have a long history of thyroid nodules, early asymptomatic or only mild palpitation, weight loss, fatigue, with the development of the disease, patients with varying degrees of thyroid poisoning symptoms, most patients with symptoms of hyperthyroidism, Individual hyperthyroidism can occur.

Most benign thyroid tumors except the functional autonomic thyroid tumor see isolated nodules of the thyroid gland, and a few are multiple nodules. The course of the disease is slow, and there can be no clinical symptoms in the clinic. Most of them are in the months to years or even longer. Because of slight discomfort or the mass is more than 1cm or even more, no symptoms are found, and B-ultrasound is performed during routine physical examination. A neck mass was found. B-ultrasound can clearly distinguish the thyroid mass is cystic or substantial, color B-ultrasound can also observe the blood flow of the mass, in order to provide a reference for the diagnosis of benign and malignant tumors, blood flow can be malignant.

Fine needle aspiration cytology (FNA) of thyroid nodules is the most accurate and cost-effective diagnostic method for preoperative evaluation of thyroid nodules. It is routinely used in foreign hospital guidelines, and FNA is able to diagnose thyroid malignancies earlier. Avoid unnecessary surgery in patients with benign thyroid disease. The biggest difficulty in pathological diagnosis of thyroid follicular carcinoma is the identification of follicular carcinoma and follicular adenoma.

 

How to identify follicular carcinoma and follicular adenoma?

The criteria for the identification of follicular carcinoma and follicular adenoma: the follicular tumor lacks the characteristic structure of papillary carcinoma. The only criterion for distinguishing between cancer and adenoma is that follicular carcinoma has vascular or envelope invasion, which means that the two are reliably distinguished. It needs careful check at the junction of the tumor and the thyroid. Although the following features are likely to be follicular carcinomas, if no invasive evidence after careful histology examination is found, they are still referred to as follicular adenomas:(1) Thick fibrous envelope.(2) Cell dense, solid, beam or microfollicular growth mode.(3) diffuse nuclear atypia.(4) mitotic figures are easy to see.(5) Because the microinvasive follicular carcinoma has a good prognosis, the infiltration criteria must be strictly controlled to avoid overdiagnosis.

Fine needle aspiration and smear staining method: a tissue was taken with a 10 ml syringe and a 0.7 x 30 needle. Make sure the specimens are fresh and make samples as soon as possible after taking the materials. At least two slides should be applied to each patient's specimen to avoid missed diagnosis. The smear is pushed by the method, and the appropriate amount of the puncture solution is dropped on the right side of the slide, and the puncture on the slide is gently pushed to the left by the pusher at an angle of 30 degrees. With wet fixation, HE staining.

Puncture results were judged according to the Pap cytopathology association's diagnosis strategy for thyroid fine needle aspiration. The cytological results were divided into six grades: undiagnosed, benign, atypical cells, follicular tumors, suspected malignant and malignant. The criteria for determining FNA results were postoperative routine histopathological findings and FNA results were compared with histopathological findings.

In general, follicular carcinoma is similar to follicular adenoma: there is a complete, significantly thickened envelope. Under the microscope, the tumor has a small follicular or trabecular type of tissue structure and the same cell morphology, both of which can be seen bleeding, necrosis, infarction, and division. The main points to identify the two are: capsule invasion and vascular invasion, both of which have one.

 

How to determine the infiltration of the capsule and vascular infiltration in the actual work?

How to determine the capsule infiltration and vascular infiltration is often a problem, the judgment criteria are often not uniform, easy to cause diagnostic difficulties.

(1) Envelope infiltration: The fibrous envelope must be completely penetrated; that is, the tumor nest must exceed the outer contour imaginary line of the envelope. The problems encountered in assessing the infiltration of the envelope are explained by the figures. Tumors that still lack complete envelope invasion should not be diagnosed as cancer after extensive evaluation, although some believe that incomplete capsule invasion is sufficient to diagnose follicular cancer. One major differential diagnosis is the rupture of the capsule caused by fine needle aspiration. Vascular infiltration and envelope infiltration are actually closely related. Tumor infiltration is often present in tumors showing vascular infiltration, and the tumor nest often invades or penetrates the capsule and extends directly into the blood vessel. It is necessary to see that the tumor "cuts" the collagen fibers of the envelope to create a gap. The collagen fibers of the tumor capsule are not subjected to "cutting" of extrusion, invagination, residue, etc., and cannot be treated as an envelope.

(2) vascular invasion: the affected blood vessels must be located outside the fibrous envelope or capsule, and the surface of the tumor cell mass in the blood vessel needs to be covered with endothelial cells. Only when the tumor cell mass adheres to the blood vessel wall with thrombosis, the tumor cell island may not be required to coat the endothelial cells. For follicular masses that protrude slightly into the thin-walled blood vessels of the envelope, there is no clear vascular infiltration if deep and further materials are taken. The contraction artifact around the tumor island is similar to vascular invasion, but the fissure is not covered by endothelial cells. Occasionally, irregular tumor cell clusters that are inconsistent with the contour of the blood vessels, have uneven borders, and are not covered by endothelial cells in the envelope vessels are caused by manual displacement during specimen cutting and should not be considered as vascular infiltration. A rare condition similar to vascular invasion is endothelial cell proliferation of the enveloped blood vessels. Careful observation reveals that intravascular polypoid lesions consist of obese spindle-shaped endothelial cells and pericytes, which are distinct from neoplastic follicular epithelial cells. There are two conditions for vascular invasion: a. blood vessels in the capsule or outside the capsule; b. tumor mass in the blood vessels is surrounded by vascular endothelial cells. The standard of vascular invasion is set in the capsule or in the extracapsular blood vessels because it is a common phenomenon in the blood vessels in the tumor in the capsule, and there is no prognostic significance. In addition, the true vascular infiltration, the periphery of the tumor mass is surrounded by the vascular endothelium, and the tumor mass in the blood vessel without the blood vessel endothelium is caused by human illusion. Because follicular carcinoma has the characteristics of vascular invasion (papillary carcinoma is mainly lymphatic infiltration), vascular invasion is more practical than envelope invasion.

The role of immunohistochemistry in the diagnosis of follicular tumors Unless the tumor has special morphological features, such as obvious fibrovascular septa, signet ring cells, clear cells or glass-like beam-like structures, immunohistochemistry is usually not required. The follicular nature of the tumor can be confirmed by thyroglobulin or TTF-1 positive. Studies have been conducted on the potential value of multiple antibodies in identifying follicular and follicular adenomas, but so far there are no reliable indicators.