Small cell carcinoma of the thymus

Introduction to thymocyte small cell carcinoma Small thymocyte cancer (thymocyte cancer) has fewer onset. Histology and electron microscopy thymocyte cancer is similar to small cell carcinoma in other parts of the body. Tumor cells contain a large number of neuroendocrine granules. Small cell thymoma is invasive and prone to distant metastasis. Small cell carcinoma of the thymus often occurs simultaneously with endocrine tumors of other organs of the body, namely multiple neuroendocrine tumor (MEN) type I syndrome. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: myasthenia gravis

Causes of thymocyte small cell carcinoma

Cause:

Because there is no reliable basis for the pathology of oat cell carcinoma originating from the thymus or the primary lung, it is necessary to completely exclude the oat cell carcinoma originating from the lung before the diagnosis of primary thymocyte cancer. The difference between oat cell carcinoma and carcinoid tumors is that the former tumor cells have very few cytoplasm, more mitotic figures, adenoid cancer nests are rare, and some tumors with a cell morphology between them are often called "atypical". Cancer" or "neuroendocrine cell carcinoma."

Pathogenesis

Srover et al. have described three omega cell carcinomas with squamous cell carcinoma that originate in the thymus. In these tumors, squamous epithelial cancer cells form small cancer nests scattered in oat cell cancer cells, under light microscope, two The cancer cells are clearly demarcated. Since this similar mixture can be found in the primary bronchogenic tumor, this case must exclude the possibility of transferring from elsewhere to the mediastinum. Electron microscopy features: ultrastructure, thymic oat cell carcinoma Consisting of dense polygonal cells, the cytoplasm adjacent to the cancer cells is obtuse-angled, and is not completely surrounded by the basement membrane material. The intercellular space is filled with a mixture of collagen and flocculent granular matrix, occasionally in the cell nest. Due to the pseudo-glandular cavity formed by cell necrosis, the intercellular junctions are punctate, always present, but not abundant. The nucleus is oval or slightly irregular, and the chromatin is evenly distributed. Some cytoplasm can isolate the nuclear membrane. The formation of pseudo-inclusion bodies in the nucleus, often without nucleoli, is abundant in the cytoplasm of tumor cells. The neurosecretory granules with high-density core surrounded by membranes are generally 140-150 m in diameter. In the known tumors, the conclusions about the diameter are often consistent. Occasionally, similar to the exocytosis in pituitary prolactinoma, the rough endoplasmic reticulum is very rich in the hormone-secreting tumor cells, parallel or Concentrically arranged; the number of Golgi bodies is also significantly increased; thymic omega cell carcinoma that synthesizes ACTH also exhibits a rich smooth endoplasmic reticulum.

Thymic oat cell cancer cells are rich in cytoplasm. Among them, intermediate filaments are common, sometimes forming a spiral structure around the nucleus. Some dense granules are visible in the nucleus. In the case of intercellular junction complex, thymic oocyte cancer is more than thymic carcinoid. Obviously, the squamous epithelial differentiation lesions in the tumor seen under light microscopy showed cytoplasmic tension filaments in the ultrastructure, and it is worth noting that dense nucleus particles were also observed in the squamous epithelial cells.

Thymic small cell carcinoma prevention

1. Have a good attitude to cope with stress, work and rest, not excessive fatigue. Visible pressure is an important cause of cancer. Chinese medicine believes that stress causes cancer to prevent physical weakness, which leads to decreased immune function, endocrine disorders, metabolic disorders in the body, leading to the deposition of acidic substances in the body. Stress can also lead to qi stagnation and blood stasis caused by mental stress. Poisonous fire invagination and so on.

2. Strengthen physical exercise, enhance physical fitness, and exercise more in the sun. Excessive sweating can excrete acidic substances in the body with sweat, avoiding the formation of acidic constitution.

3. Do not eat contaminated food, such as contaminated water, crops, poultry, eggs, moldy foods, etc., eat some green organic food (other than green vegetables), especially to prevent the disease from entering the mouth.

Thymic small cell carcinoma complications Complications Myasthenia gravis

Thymic small cell carcinoma is a common autoimmune-associated mediastinal tumor. Often accompanied by myasthenia gravis (40%) or immunodeficiency. 50% to 60% asymptomatic, accidentally found during physical examination. 18% of patients with thymoma have general systemic symptoms such as weight loss, fatigue, fever, night sweats and other non-specific symptoms. Symptoms of thymic disease are a complex systemic condition that may be associated with thymoma as many as 30 diseases, the most common of which are: myasthenia gravis, simple red cell aplastic anemia, hypogammaglobulinemia , extrathymic malignant tumors. These diseases may occur at the same time, after or after resection of the thymoma.

Thymic small cell cancer symptoms Common symptoms Chest pain Fatigue night sweats Parathyroid function hyperactivity Cushing's syndrome hemoptysis

Small cell carcinoma of the thymus is more common in male patients. The age of onset is more than 10 to 60 years old. Nearly half of the patients are asymptomatic before the operation is diagnosed. Most of them are unintentionally found in chest X-ray examination. A few patients have only chest pain, cough, hemoptysis. Non-specific symptoms such as shortness of breath, if the tumor invades the superior vena cava, the superior vena cava syndrome may occur. Individuals may also exhibit fatigue, fever, night sweats, etc., and 1/3 of patients with small cell thymocytes often appear before diagnosis. Cushing syndrome (Cushing syndrome), which is caused by the production of atopic ACTH by neuroendocrine cells in thymocyte small cell carcinoma, other endocrine disorders such as vasopressin hypertrophy, hyperparathyroidism, islets Cell tumor, multiple endocrine neoplasia type I syndrome, horse syndrome and hypertrophic osteoarthrosis are rarer than thymic carcinoid, thymocyte small cell carcinoma is prone to distant metastasis with thymic carcinoid, and 1/3 of patients are seen There may be distant metastases of bone or skin.

Examination of thymocyte small cell carcinoma

Cytological examination :

Cytological specimens appear as loose and irregular or syncytia-like clusters of cells, and can also be expressed as a single tumor cell in a linear arrangement. Significant nuclear notches were observed in adherent cell aggregates. The mitosis is easy to see. The nuclear/slurry of each tumor cell is relatively high and its shape is oval to irregular. The well-fixed cell features a fine-grained uniformly distributed chromatin with a typical "salt-salt" appearance, while poorly-fixed cells show chromatin that is unstructured and deeply stained, lacking a distinct nucleolus or pole. Rare. Due to the fragility of malignant nuclei, streaked chromatin is often seen on all types of sections, especially in aspiration biopsy and brushing specimens. In addition, apoptotic bodies and granular necrotic debris are often present in the background of the sections.

Diagnosis and differentiation of thymocyte small cell carcinoma

diagnosis

Clinical manifestations are not specific, and pathological biopsy is the only diagnostic tool. Before the diagnosis, other parts of the primary small cell carcinoma, such as small cell lung cancer, must be excluded.

Differential diagnosis

Thymic oat cell carcinoma and oat cell carcinoma are pathologically differentiated from other diseases.

Epithelial thymoma

The intranuclear chromatin of thymoma is not as homogeneously distributed as thymocyte cancer, and is often divided into lobular shape by internal fibrous cords. The thymocyte cancer is positive for chromogranin immunohistochemical staining, while thymoma is negative.

2. Thymic parathyroid adenoma

This tumor patient often has hypercalcemia in the clinic, which is opposite to the characteristics of endocrine pathological damage, but in some cases, there are no symptoms caused by hormones, which is easy to be confused with thymoid tumors. The points are significantly different: most parathyroid adenomas do not have the characteristics of necrotizing vascular-like growth and daisy-like clusters in typical thymic oat cell carcinoma, and PAS staining is strongly positive, under electron microscope, parathyroid adenoma The neurosecretory granules are much less than the thymic oat cell carcinoma. In immunohistochemistry, the parathyroid hormone immunohistochemical staining of the parathyroid adenoma is positive, while the thymic oocyte cell carcinoma is negative.

3. Mediastinal paraganglioma

Morphologically similar to thymic oat cell carcinoma, but it does not necessarily appear in the thymus, but often occurs in the large blood vessels; because it originates from the aorta, the pulmonary artery or the intravascular accessory ganglion, the same thymus Ovarian cell carcinoma has different glandular growth patterns. Paraneoplastic tumor cells grow tightly clustered. In addition, paraganglioma mitotic figures are rare, while thymic oocyte cell carcinoma is more common in mitotic figures. It is positive in paraneurma, while thymocyte cancer is negative, both methionine enkephalin and leucine enkephalin staining are positive, but more common in paraganglioma.

Thymic metastatic carcinoma

Some of these cases are very similar to thymocyte cancer, which is difficult to diagnose. On the contrary, thymocyte cancer, which is screen-like growth, is often a secondary tumor, not a primary thymus lesion. The lung and intestinal carcinoids are rarely metastasized. There was no obvious lesion in the primary lesion to the mediastinum.

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