【One case per day】Yolk sac tumor

【Case introduction】

The patient is a 17-year-old man who coughed up sputum for 1 month and worsened for 7 days
.
Before 1 month, there was no obvious cause of cough, coughing up white sputum, no fever, night sweats, chest tightness, chest pain and other discomfort
.
AFP: 133.
420; CA199:45.
01; CA50:32.
36; TAP tumor-specific protein: 560.
3; NSE neurogen-specific enolase: 33.
35; CA125:82.
33; CYFRA211 non-small cell lung cancer marker: 17.
90

Chest Enhancement Scan:

Premediastinal mass biopsy under local anesthesia: pathologic findings show yolk sac tumor.

Yolk sac tumor, also known as endodermal sinus tumor, is a highly malignant germ cell tumor
formed by differentiation from pluripotent germ cells in the direction of extraembryonic structures.
It occurs in germ cells and embryologies along the migration of germ cells from the yolk sac to the gonads, mostly in the ovaries and testes, followed by the sacrococcyge, pineal gland, mediastinum, posterior peritoneum, liver, stomach, prostate and vagina
.

The number of cases of yolk sac tumor occurring in the mediastinum is small, and the literature reports that its CT enhancement is characterized by mild to moderate uneven strengthening of the mass, and in this case, CT enhancement is manifested as obvious strengthening around the tumor foci and gradually filling
towards the center.
Yolk sac tumor cells can produce alpha-fetoprotein (AFP), and a higher concentration of AFP can be measured in the patient's serum, which is balanced with the growth and decline of the tumor, and has become an important marker in diagnosis and treatment monitoring
.

On CT, it is necessary to distinguish from invasive thymoma and lymphoma, lymphoma is a mass fused with multiple enlarged lymph nodes, the enhancement is significantly strengthened, the whole body can have multiple lymph nodes enlargement, AFP is not elevated; Aggressive thymoma may be accompanied by muscle weakness, and AFP is not significantly increased; Combined with elevated clinical AFP can help in the diagnosis
of yolk sac tumor.

In short, CT can preliminarily determine the source, extent and relationship
of the mass with surrounding organs.
Combined with the patient's age, clinical symptoms and blood AFP examination, the diagnosis depends on pathological examination, and the immunohistochemical staining of yolk sac tumor is positive for AFP, AAT, and negative
for HCG.
Immunohistochemical staining of germalocypomas was positive
for CD117 and Vinetin.