Low-grade tumor malignancy

Grading of malignancy in pathomorphology

A grading system (Grade) is used to assess the aggressiveness of neoplasms. According to standard pathomorphological criteria, several main categories of cell differentiation and malignancy are distinguished:

• Low grade (Low Grade).
• Intermediate grade (Intermediate Grade).
• High grade (High Grade).
• Undetermined grade (Grade X).

The low grade category is used to describe both early intraepithelial changes (precancerous states) and already established non-invasive carcinomas. The progression of a tumor to the high grade category according to biopsy or cytologic analysis is a marker of a worsened prognosis.

Glandular, intraductal, and mucinous neoplasms

Assessment of the degree of dysplasia is of critical importance in the diagnosis of cystic and ductal tumors of the digestive system (including the biliary tract and pancreas). Neoplasms classified with a low grade stage include:

1. Glandular intraepithelial neoplasia. At low malignancy, it is coded as 8148/0, and at high malignancy, as 8148/2. A similar coding system is applied to biliary intraepithelial neoplasia (BilIN).
2. Intraductal papillary mucinous neoplasm. The variant with low-grade dysplasia has the code 8453/0 (as opposed to high grade — 8453/2).
3. Intraductal papillary neoplasm (IPNB). Divided into formations with low-grade intraepithelial neoplasia (8503/0), high-grade (8503/2), and tumors combined with invasive carcinoma (8503/3).
4. Mucinous cystic neoplasm (MCN). Evolves from low-grade intraepithelial neoplasia (8470/0) to high-grade dysplasia (8470/2) and combination with invasive carcinoma (8470/3).

Benign neoplasms may also be diagnosed in adjacent tissues (e.g., serous cystadenoma 8441/0, bile duct adenoma 8160/0, or adenofibroma NOS 9013/0). Meanwhile, certain ductal tumors, such as intraductal oncocytic papillary neoplasm (8455/2) and intraductal tubulopapillary neoplasm (8503/2), are immediately classified with behavior code /2.

Neoplasms of the urothelial tract

In urological practice, the low grade category is used for the stratification of papillary urothelial tumors. This is necessary for selecting treatment tactics and patient monitoring. The histological classification distinguishes the following grades:

• Papillary urothelial neoplasm of low malignant potential (PUNLMP).
• Low-grade papillary urothelial carcinoma (low grade) (Low grade).
• High-grade papillary urothelial carcinoma (high grade) (High grade).

The presence of a low grade status indicates a highly differentiated tumor structure and a relatively favorable clinical course compared to high-grade carcinomas.

Criteria for transition to the high-risk group

Despite the fact that a low-grade tumor diagnosis initially implies a less aggressive growth pattern, there are a number of clinical and morphological factors capable of radically altering the prognosis. The presence of any of the following signs immediately places the patient in the high-risk group:

• Histology and cytology: detection of high malignancy (High Grade) according to cytological examination or biopsy, as well as the presence of a specific histological tumor variant (other than typical urothelial cancer).
• Size: neoplasm diameter exceeds 2 cm.
• Spread: multifocal tumor (presence of multiple growth foci in the organ).
• Complications: development of hydronephrosis against the background of the tumor process.
• History: history of bladder cancer (including status post cystectomy).

Class and exam questions

What else to study on this topic

• Morphological characteristics of serous cystadenoma (8441/0)
• Histological features of intraductal oncocytic papillary neoplasm (8455/2)
• Specific variants of urothelial cancer increasing risks
• Diagnosis of hydronephrosis as a complication of the tumor process
• Intraductal tubulopapillary neoplasm (8503/2): clinical significance

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.