Page 217 - Textbook of Pathology, 6th Edition

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CHAPTER 8

Figure 8.11 Regional nodal metastasis. A, Axillary nodes involved by carcinoma breast. B, Hilar and para-tracheal lymph nodes involved by Neoplasia
bronchogenic carcinoma. C, Lymphatic spread begins by lodgement of tumour cells in subcapsular sinus via afferent lymphatics entering at the
convex surface of the lymph node.

It is believed that lymph nodes in the vicinity of tumour of cancer cells are capable of clonal proliferation in the proper
perform multiple roles—as initial barrier filter, and in environment; others die without establishing a metastasis.
destruction of tumour cells, while later provide fertile soil Systemic veins drain blood into vena cavae from limbs,
for growth of tumour cells. head and neck and pelvis. Therefore, cancers of these sites
Mechanism of lymphatic route of metastasis is discussed more often metastasise to the lungs.
later under biology of invasion and metastasis.
Portal veins drain blood from the bowel, spleen and
2. HAEMATOGENOUS SPREAD. Blood-borne metastasis is pancreas into the liver. Thus, tumours of these organs
the common route for sarcomas but certain carcinomas also frequently have secondaries in the liver.
frequently metastasise by this mode, especially those of the lung,
breast, thyroid, kidney, liver, prostate and ovary. The sites Arterial spread of tumours is less likely because they are
where blood-borne metastasis commonly occurs are: the thick-walled and contain elastic tissue which is resistant to
liver, lungs, brain, bones, kidney and adrenals, all of which invasion. Nevertheless, arterial spread may occur when
provide ‘good soil’ for the growth of ‘good seeds’ (seed-soil tumour cells pass through pulmonary capillary bed or
theory). However, a few organs such as spleen, heart, and through pulmonary arterial branches which have thin walls.
skeletal muscle generally do not allow tumour metastasis to Cancer of the lung may, however, metastasise by pulmonary
grow. Spleen is unfavourable site due to open sinusoidal arterial route to kidneys, adrenals, bones, brain etc.
pattern which does not permit tumour cells to stay there long Retrograde spread by blood route may occur at unusual
enough to produce metastasis. In general, only a proportion sites due to retrograde spread after venous obstruction, just

Figure 8.12 Metastatic carcinoma in lymph nodes. A, Matted mass of lymph nodes is surrounded by increased fat. Sectioned surface shows
merging capsules of lymph nodes and replacement of grey brown tissue of nodes by large grey white areas of tumour. B, Masses of malignant cells
are seen in the subcapsular sinus and extending into the underlying nodal tissue.