Metastases

Metastases are usually an ominous finding. They are not always obvious when in encounter; thus, they should be considered with every diagnosis of a malignant tumour.

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.

Special types

In-transit metastasis

Definition - the separate tumour nodule must be:

1. >2 cm from the primary tumour.
2. Arises between the nearest (regional) lymph nodes and the primary tumour.
   • The tumour presumably arises from a lymphatic that drains the tissue in which the primary tumour grew.

Notes:

• It is called "in-tranist", as it happens while the tumour is on the way to the regional lymph node.
• In-transit metastases are seen in malignant melanoma, merkel cell carcinoma.
• If a separate tumour nodule <= 2 cm from the primary tumour, it is known as satellitosis.

Specific sites

Internal organs

• Main article: Liver metastasis
• Main article: Kidney metastasis

Lymph node

Main article: Lymph node metastasis

Other

Main article: Peritoneal metastasis

Brain

Main article: Brain metastasis

Specific tumours

Melanoma

Main article: Metastatic melanoma

Osteosarcoma

Main article: Osteosarcoma

• Giant cells.

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.

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

• Cancer.
• Basics.
• Pulmonary lymphangitic carcinomatosis.