It is true that sarcoma -

Ans. is 'a' i.e., Are malignant tumours of mesenchyme origin & Usualy spread by vascular invasion o Distant metastasis of cancers may occur through one of three pathways. 1. Direct seeding of body cavities or surface o It occurs when a malignant neoplasm penetrates into a natural open field. o Most common cavity involved is peritoneal cavity, but other cavities may also be involved, e.g., pleural, pericardial, joint space, subarachnoid. Such seeding is paicularly characteristic of carcinomas arising in the ovaries. o Sometimes mucus secreting tumor of appendix (or less commonly ovary) fill the peritoneal cavity with a gelatinous neoplastic mass referred to as pseudomyxoma peritonei. 2. Lymphatic spread o This is the most common method of metastasis for carcinomas. Sarcoma may also use this route. o As tumors do not have lymphatics, this type of spread takes place through the lymphatic vessels located at the tumor margins. The pattern of lymph node involvement follows the natural routes of lymphatic drainage. o The first node in a regional lymphatics that receives lymph flow from the primary tumor is called sentinel lymphnode. Some times local lymph nodes may be bypassed because of venous lymphatic anastomosis -4 skip metastasis. 3. Hematogenous spread It is typical of sarcomas but is also seen in carcinomas. o Veins are more commonly involved than aeries because veins have thinner walls that can be penetrated readily, in contrast aeries have thicker walls. With venous invasion, the tumor cells in blood follow the venous flow draining the site of neoplasm. So, liver and lung are the most frequent organs involved in hematogenous spread because all poal area drainage flows to the liver and all caval blood flows to the lung. o Aerial spread may occur when tumor cells pass through the pulmonary capillary beds or pulmonary A-V shunts or when pulmonary metastasis give rise to additional tumor emboli.