Key Points of Ovarian Mucinous Tumor

Key Points of Ovarian Mucinous Tumor

Key Points of Ovarian Mucinous Tumor.   In clinical work, mucinous ascites or mucinous nodules attached to the surface of the peritoneum are much more common than primary mucinous tumors of the ovary, but there is no consistent description in histopathology.

Compared with serous tumors of ovarian mucinous tumors, serous tumors are much more complicated in terms of knowledge system. However, this does not mean that the mucinous tumor itself is simple, but the difficulty is different.However, this does not mean that the mucinous tumor itself is simple, but the difficulty is different. Before the article starts, let’s discuss the following questions:

1) How to define mucinous tumor? Diagnosis basis: It has the characteristics of intestinal epithelium.

2) How to clarify benignity? Borderline? And vicious? Diagnosis basis: a: heterosexual type of nucleus (heterotype of nucleus is particularly important in mucinous tumors); b: presence or absence of infiltration (there are many details to explain).

3) If it is a malignant tumor, is it the source of the ovary? Or is it a metastatic tumor? Ovarian-derived malignant tumors and metastatic mucinous tumors have completely different prognosis. Therefore, distinguishing whether it is metastasis is the focus and difficulty of diagnosing mucinous tumors.

Next, let’s take the above questions to sort out the knowledge system of ovarian mucinous tumors.

Mucinous cystadenoma/adenofibroma

The definition given by the WHO is: a benign, cystic tumor, covered with mucinous gastrointestinal epithelium; occasionally obvious fibrous interstitium.

Through the definition, we draw the following conclusions:

1) Macroscopically, it is a tumor with multilocular cystic section.

2) The gastrointestinal epithelium is covered under the microscope.

3) When there is obvious fibrous stroma, the diagnosis is: adenofibroma.

With the concept of focal epithelial hyperplasia:

When the tumor is mainly mucinous cystic tumor, but with <10% atypical components, it should be diagnosed as mucinous cystic tumor with focal epithelial hyperplasia. The 10% here means that the total content of all atypical regions does not exceed 10%. Atypical components refer to mild-to-moderate nuclear atypia.

The concept of ovarian pseudomyxoma:

When more than 10% of the tumor stroma has acellular mucus, it is called pseudomyxoma of the ovary. It is not difficult to infer that the 10% here is also the cumulative result.

Brenner tumor components & mixed mucus-the concept of Brenner tumor:

Nearly 18% of mucinous cystadenomas can be found in transitional cell nests, also known as Brenner tumor components, which are considered to be concurrent Brenner tumors.

Only when the Brenner tumor is the main component and mixed with the mucinous component will it be diagnosed as: mixed mucin-Brenner tumor.

Based on these findings, it is speculated that most intestinal mucinous tumors are derived from Brenner tumors or transitional cell nests.

Atypical hyperplastic mucinous tumors (borderline mucinous tumors)

Borderline mucinous tumor, with mild aberration of epithelial cells

Initially, borderline ovarian tumors were proposed mainly for serous tumors, and then this concept was extended to mucinous tumors. Typical mucinous borderline tumors have the following characteristics:

1) Large size (average diameter 20-22cm), unilateral, multi-chambered, smooth inner wall, and generally no obvious nipple structure.

2) The microscopic appearance can refer to “low-grade tubular adenoma”.

3) The nucleus is mild to moderately heterogeneous, and this area must exceed 10% of the total to report borderline sex.

4) Lack of interstitial infiltration.

What needs to be explained here is that in borderline tumors, 20% of cases are manifested as ovarian pseudomyxoma; when granulomatous stroma appears, the glands are ruptured and mucus is common.

The concept of intraepithelial carcinoma:

The small foci have a vesicular nucleus, a severe nuclear atypia with obvious nucleoli, and are confined to the epithelium, which is called intraepithelial carcinoma. It should be noted here that in the absence of severe heterogeneity of cells, even if the cribriform structure itself exceeds 3 layers of cells, it cannot be characterized as intraepithelial carcinoma, that is, structural atypical type is not a decisive factor in the diagnosis of intraepithelial carcinoma.

The concept of micro-invasive & micro-invasive carcinoma:

Borderline mucinous tumor with micro-infiltration, the largest diameter of a single infiltrating foci <5mm

Microinfiltration is defined as: small foci of interstitial infiltration, the largest diameter is less than 5mm, there is no need to consider the number of infiltrating foci, and the cells are mild to moderate atypia.

When the growth pattern is similar, but the atypia is more obvious, severe atypia should be classified as: microinvasive carcinoma.

The concept of serous mucinous tumors:

Borderline serous mucinous tumor, see complex papillary structure

1) Smaller size, more common on both sides, structure similar to borderline serous tumor, multi-level branched papillary structure.

2) Related to endometriosis.

3) The endocervical epithelium (monolayer columnar) and serous epithelium (with cilia) are mixed.

Personally, the key to diagnosing this disease is the characteristics of its serous tumors, such as: multi-level branched papilla and ciliated epithelium.

The diagnostic principles of mucinous carcinoma and how to distinguish between primary and metastatic ovarian

Primary mucinous carcinoma of the ovary is rare in ovarian tumors. Its principles of microscopic diagnosis are as follows:

1) Typical intestinal mucinous carcinoma is often well differentiated, and various glandular tubular structures can be seen, and borderline areas are often seen next to the cancer.

2) When the tumor shows a typical borderline growth pattern, it is still diagnosed as borderline as long as it lacks significant nuclear heterogeneity or interstitial infiltration (>5mm).

3) The concept of “fusion glands” is a “special” infiltration pattern, which is manifested as the glandular epithelium is significantly crowded, fused into pieces, or maze-like, lacking interstitium. This infiltration must reach 5mm to diagnose invasive cancer.

4) Another form of infiltration is “destructive interstitial infiltration”, the exact basis for the diagnosis of cancer.

In daily work, when encountering a mucinous ovarian tumor, the first thing to rule out is whether the tumor has metastasized. Because, for patients, the prognosis of the two is significantly different, so its importance is self-evident. So, how do we identify it?

1) Key words for metastatic tumors: medical history, bilateral, <13cm, CK7 (-).

2) Key words for primary ovarian tumors: unilateral, 20-22 cm, CK7 (+).

The above method can correctly distinguish 90% of mucinous carcinomas. As for the remaining indistinguishable part, let’s discuss it inside the department…

When mucinous tumors are accompanied by: mucinous ascites & peritoneal mucous nodules

Large lakes of mucus are seen in the ovarian stroma

In clinical work, mucinous ascites or mucinous nodules attached to the surface of the peritoneum are much more common than primary mucinous tumors of the ovary, but there is no consistent description in histopathology. For the convenience of research, this manifestation is defined as the clinical syndrome of pseudomyxoma peritoneum (PMP). PMP includes the following characteristics:

1) Almost all PMPs originate from low-grade mucinous tumors of the appendix, and the ovary is the site of secondary involvement.

2) The rupture of primary mucinous tumors of the ovary has nothing to do with PMP.

3) Since almost all mucinous tumors of the ovary related to PMP originate from the gastrointestinal tract, it is diagnosed as “low-grade mucinous tumors involving the ovary” at work, and avoid using “metastatic mucinous carcinoma”.

4) When patients with PMP are diagnosed with mucinous ovarian tumors during the operation, the appendix needs to be removed, and the gastrointestinal tract and pancreatic biliary system should be thoroughly examined.

5) When the PMP is low-grade under the microscope, it can be diagnosed as: disseminated peritoneal mucinosis; when it is high-grade, it can be diagnosed as: invasive mucinous carcinoma.

6) A small number of PMPs originate from mature cystic teratomas of the ovary and are classified as germ cell tumors.

When mucinous tumors are accompanied by: mural nodules

On the left is the mucinous epithelium of the tumor, and on the right is the mural nodules

What is a “mural nodule”? It is a nodule “hanging” in the wall of the tumor cyst. For the time being, it can be simply understood as an interstitial reaction. This is also the reason why it has both “cancer” and “sarcoma” components, but not all of them. Mural nodules are all malignant, and whether they are malignant depends on whether they are malignant under the microscope. All types of mucinous ovarian tumors can be accompanied by mural nodules. There are 3 types of mural nodules:

1) Sarcoma-like nodules: mostly nodules composed of spindle cells, histiocytes and inflammatory cells.

2) Anaplastic cancer: component of cancer.

3) True sarcoma: components of sarcoma.

It is important to note that mucinous tumors with malignant mural nodules are best classified as mucinous carcinoma or carcinosarcoma, and 50% of malignant mural nodules are fatal.

Summarize the main points:

When encountering mucinous ovarian tumors, the first thing to be excluded is the metastasis. According to the size, unilateral and bilateral, and CK7 expression, we can clearly classify 90% of the tumors. Secondly, the key to diagnosing benign, borderline, or malignant lies in two points: a) the heterogeneous type of the nucleus; b) whether the interstitial infiltration is greater than 5mm.

Finally, in the work process, there are many special cases, such as: mucinous ascites or mucinous peritoneal nodules should first consider whether there is a primary tumor of the digestive system, of course, when the head of the appendix is ​​cut off, it must be comprehensive. Check the gastrointestinal tract and pancreatic biliary system; when mural nodules appear, treat them seriously, regardless of benign or malignant, and carefully select materials.

(source:internet, reference only)

Disclaimer of medicaltrend.org