From the Guidelines
Neoplastic growth in the context of inflammatory bowel disease, such as ulcerative colitis, is best identified by the presence of dysplasia, which represents a reliable marker of malignancy risk 1.
Definition and Identification of Dysplasia
Dysplasia is defined as histologically unequivocal neoplastic epithelium without evidence of tissue invasion. It is categorized into negative for dysplasia, indefinite for dysplasia, and positive for dysplasia (low or high grade) 1. The Vienna classification proposes an alternative system, categorizing dysplasia into non-dysplastic mucosa, lesions indefinite for dysplasia, genuine dysplasia corresponding to non-invasive low-grade neoplasia, and genuine dysplasia corresponding to non-invasive high-grade neoplasia 1.
Importance of Dysplasia in Neoplastic Growth
Dysplasia may occur in any part of the colon and is most often multifocal, presenting as isolated foci. It develops only in areas with chronic inflammation and is characterized by architectural and cytological abnormalities, including crowding of glands, thickening of the mucosa, and nuclear changes such as hyperchromatic and enlarged nuclei 1. The presence of dysplasia is a key factor in determining the risk of malignancy in patients with ulcerative colitis.
Diagnostic Challenges and Recommendations
There is a poor inter-observer agreement for low-grade and indefinite dysplasia, even among experienced gastrointestinal pathologists. Therefore, confirmation of dysplasia by an independent expert GI pathologist is recommended 1. Recent studies have focused on adjunctive methods to improve inter-observer variability in detecting dysplasia, including the use of p53 tumor suppressor gene as a key factor in the initial steps of IBD-associated colorectal carcinogenesis 1.
Clinical Implications and Management
The progression of colorectal neoplastic lesions in patients with long-standing UC varies by colonic location, with a distal predominance for UC-associated CRCs. More biopsies should be taken from the rectosigmoid area during follow-up colonoscopy 1. Polypectomy may be an adequate treatment for patients with an adenoma-like dysplastic lesion, but complete excision of the lesion is necessary. Colitis-associated polypoid dysplasia has a high risk of concurrent malignancy and should be considered an indication for colectomy or proctocolectomy 1.
From the Research
Definition and Characteristics of Neoplastic Lesions
- A neoplasm is a clonal proliferation, and neoplastic conditions are consisted of a single cell type, whereas non-neoplastic conditions consist of multiple different cell types 2.
- The main differences between epithelial tumors and mesenchymal tumors include cell shape, tumor cell arrangement, presence of desmoplastic stroma, and feeding vessel pattern 2.
Diagnosis and Classification of Neoplastic Lesions
- The diagnostic approach to neoplastic lesions involves determining whether the lesion is neoplastic or non-neoplastic, and then deciding whether the neoplasm is of an epithelial origin or mesenchymal origin 2.
- The differences between benign and malignant tumors include differentiation, growth rate, growth pattern, and metastasis 2.
- Malignant tumors are often poorly differentiated, grow rapidly with many mitoses, show invasive growth with no capsule, and frequently metastasize 2.
Types of Neoplastic Lesions
- Lymphoma is a group of malignant neoplasms of lymphocytes with more than 90 subtypes, and is traditionally classified broadly as non-Hodgkin or Hodgkin lymphoma 3.
- Carcinoma of unknown primary (CUP) presents with metastatic disease without an identified primary tumour, and requires an extensive diagnostic work-up 4.
- Melanoma is a type of malignant neoplasm that requires accurate diagnosis and staging, and advanced imaging modalities and laboratory testing are important parts of the workup 5.
Metastasis of Neoplastic Lesions
- The metastasis of neoplastic cells from their site of origin to distant anatomic locations continues to be the principal cause of death from malignant tumors 6.
- The biological mechanisms of metastasis, the "sentinel" lymph node biopsy technique, and the important topic of metastatic tumor "dormancy" are currently-held concepts in the field of neoplastic lesions 6.