Evaluation of suspected malignancies

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Author: Mikael Häggström [notes 1]

General notes edit

For evaluation of suspected malignancies, the most important aspects of a tumor is whether it benign or malignant. If malignant, then staging is necessary.[1] 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

Benign[2] Malignant[2]
Gross examination
  • Well demarcated from surrounding tissue
  • Usually no tumor capsule


  • Necrosis
  • Infiltration or invasion into surrounding tissue
  • Bleeding
Microscopy Almost no irregularities of cellular structures Nuclear atypia:
  • Enlargement
  • Pleomorphism
  • Nuclear polychromasia, which means variability in nuclear chromatin content.
  • Numerous mitotic figures


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:[1]

T: size or direct extent of the primary tumor

    • Tx: tumor cannot be assessed
    • Tis: carcinoma in situ
    • T0: no evidence of tumor
    • T1, T2, T3, T4: size and/or extension of the primary tumor

N: degree of spread to regional lymph nodes

    • Nx: lymph nodes cannot be assessed
    • N0: no regional lymph node metastasis
    • N1: regional lymph node metastasis present; at some sites, tumor spread to closest or small number of regional lymph nodes
    • N2: tumor spread to an extent between N1 and N3 (N2 is not used at all sites)
    • N3: tumor spread to more distant or numerous regional lymph nodes (N3 is not used at all sites)

M: presence of distant metastasis

    • M0: no distant metastasis
    • M1: metastasis to distant organs (beyond regional lymph nodes)


If tumor is seen at edge of the sample, consider confirming the finding with adjacent microtomy levels, especially if no ink is seen on an inked surgical margin. In this case, a separation artifact in top image has removed a surgical margin of connective tissue, seen on adjacent microtomy section in bottom image.

Determine if malignant cells are located close to, or even in, any surgical resection margins.

Typing and grading

Also note "treatment effect", seen as largely fibrotic tissue, here with scattered remaining tumor cells.

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

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).


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. In such cases, step slices are taken rather than serial ones.

Main page


  1. 1.0 1.1 . Cancer staging. National Cancer Institute. Retrieved on 4 January 2013.
  2. 2.0 2.1 . General oncology. Amboss. Retrieved on 2020-01-29.