Evaluation of suspected malignancies
For evaluation of suspected malignancies, the most important aspects of a tumor is whether it benign or malignant. If malignant, then staging is necessary. There are generally specific criteria for various forms of tumors, which should be used whenever applicable, but following are some generalizations.
A general approach is to start looking at the slide which seems to contain most tumor (excluding any necrosis), facilitating a diagnosis, and shows what kind of cells to look for in the periphery.
Benign or malignant
|Microscopy||Almost no irregularities of cellular structures||Nuclear atypia:
Staging is generally done by TNM classification. Specific TNM systems should be used, as per the manual by the American Joint Committee on Cancer (AJCC), whenever applicable. Otherwise, a general system may be used:
T: size or direct extent of the primary tumor
N: degree of spread to regional lymph nodes
M: presence of distant metastasis
Determine if malignant cells are located close to, or even in, any surgical resection margins.
Typing and grading
Beyond determining overall malignancy, probable origin and staging, classification of tumors into a specific histopathologic type or grade is generally of relatively less value. In cases of clearly non-malignant tumors where it is difficult to determine the specific histopathologic type or grade, it is generally acceptable to conclude the evaluation and report it as such, unless the clinician specifically requests otherwise. For potentially malignant or high-risk tumors, typing and grading often still affects the management.
Additional slices are indicated in the following situations
- Re-excision does not identify tumor cells in a clearly non-radical primary excision or biopsy.[notes 2]
- The most aggressive pattern is seen in the last available section, in which case more sections are indicated (from the same paraffin block if additional tissue is not available).