Metastases

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Metastases are tumours that have spread from elsewhere and are separate from the initial (primary) lesion; usually, they are an ominous finding.

Metastases are not always obvious when encountered; thus, metastasis should be considered with every diagnosis of a malignant tumour.

Seen from pathology, metastatic disease and direct extension of a tumour (on a biopsy) may be indistinguishable. Collectively, they may also be referred to as secondary tumours.

Cancers of unknown primary are dealt with in the cancer article. A general approach to undifferentiated tumours is given in the basics article under the heading modified general morphologic DDx of malignancy.

Lymph node metastases are dealt with in the article lymph node metastases.

A handful of things have metastatic-like behaviour but are not malignant. Examples of benign things with metastatic-like behaviour are: benign metastasizing leiomyoma,[1] endometriosis, endosalpingiosis and benign nevus cells (in lymph nodes).[2]

Special types

In-transit metastasis

  • It is called "in-transit", as it happens while the tumour is on the way to the regional lymph node.
  • If a separate tumour nodule is close to the primary tumour, it is known as satellitosis.

Note:

Specific sites

Internal organs

Lymph node

Other

Brain

Specific tumours

Melanoma

Osteosarcoma

IHC

  • Dependent on (suspected) primary.

Not necessary to do stains/immunostains if all of the following are true:

  1. A primary is already established by pathology.
  2. The morphology of the lesion is compatible with the established primary.
  3. The clinical impression is a metastasis.
  4. The suspected primary is not breast.
    • ASCO/CAP guidelines state that ER and PR (in breast cancer recurrences) should always be re-tested.[4]

Sign out

This depends somewhat on the tumour. A synoptic is not done. Margin status should be commented on. A morphologic description is useful if a subsequent resection is done.

Bowel

SMALL BOWEL, RESECTION:
- METASTATIC ADENOCARCINOMA, SEE COMMENT.
- SURGICAL MARGINS NEGATIVE FOR MALIGNANCY.

COMMENT:
The tumour involves only the outer aspect of the bowel wall; the bowel mucosa is
not involved.

The tumour consists of glands with cuboidal tumour cells that have a moderate quantity of
pale cytoplasm, and round nuclei. The tumour is moderately differentiated.

Spine

Pending

VERTEBRAL LESION, L1, BIOPSY:
- ADENOCARCINOMA -- PENDING IHC.
LESION OF T7 VERTEBRA, CORE BIOPSY:
- METASTATIC CARCINOMA, CONSISTENT WITH BREAST PRIMARY, SEE COMMENT.

COMMENT:
The morphology is compatible with a metastatic breast carcinoma.

The tumour cells stain as follows:
POSITIVE: CK7, ER, PR, MAMMOGLOBIN.
NEGATIVE: CK20, TTF-1, CDX2, HER2, GCDFP.

The immunostaining profile is compatible with a metastatic breast carcinoma.

ER, PR and HER2 are interpreted as Class I IHC tests (results used by pathologists),
as per the CAP classification.[1]

1. Am J Clin Pathol 133 (3):354-65.

Micro

Probable lung metastasis

The sections show atypical cohesive cuboidal-to-low columnar cells with moderate nuclear pleomorphism. The nuclei are round/ovoid and eccentrically placed in the cell. Nucleoli of moderate size are identified. Mitotic figures are present. The cytoplasm is lightly eosinophilic and vacuoles are seen focally.

See also

Reference

  1. Pitts, S.; Oberstein, EM.; Glassberg, MK. (Jun 2004). "Benign metastasizing leiomyoma and lymphangioleiomyomatosis: sex-specific diseases?". Clin Chest Med 25 (2): 343-60. doi:10.1016/j.ccm.2004.01.014. PMID 15099894.
  2. Cook, MG. (Oct 2004). "Benign melanocytic lesions mimicking melanomas.". Pathology 36 (5): 414-8. doi:10.1080/00313020412331283842. PMID 15370110.
  3. Puppa, G.; Ueno, H.; Kayahara, M.; Capelli, P.; Canzonieri, V.; Colombari, R.; Maisonneuve, P.; Pelosi, G. (Mar 2009). "Tumor deposits are encountered in advanced colorectal cancer and other adenocarcinomas: an expanded classification with implications for colorectal cancer staging system including a unifying concept of in-transit metastases.". Mod Pathol 22 (3): 410-5. doi:10.1038/modpathol.2008.198. PMID 19136930.
  4. Hammond, ME.; Hayes, DF.; Dowsett, M.; Allred, DC.; Hagerty, KL.; Badve, S.; Fitzgibbons, PL.; Francis, G. et al. (Jul 2010). "American Society of Clinical Oncology/College of American Pathologists guideline recommendations for immunohistochemical testing of estrogen and progesterone receptors in breast cancer (unabridged version).". Arch Pathol Lab Med 134 (7): e48-72. doi:10.1043/1543-2165-134.7.e48. PMID 20586616.