Sarcoma of the soft tissues spread by
**Core Concept**
Soft tissue sarcomas are a heterogeneous group of malignant tumors that arise from mesenchymal cells, which can include fibroblasts, fat cells, and blood vessels. The primary mode of spread for soft tissue sarcomas is through the bloodstream, specifically via hematogenous dissemination, and lymphatic spread is less common.
**Why the Correct Answer is Right**
Soft tissue sarcomas metastasize through the bloodstream due to their vascular nature. They often express vascular endothelial growth factor (VEGF), which promotes angiogenesis and facilitates the formation of new blood vessels. This enables the tumor cells to invade the bloodstream and spread to distant sites, such as the lungs, liver, and bones. The primary sites for hematogenous metastasis include the lungs, liver, and bones, which receive a high blood flow and are rich in sinusoidal capillaries that can capture tumor cells.
**Why Each Wrong Option is Incorrect**
**Option A:** Lymphatic spread is less common in soft tissue sarcomas, as they primarily metastasize through the bloodstream. Lymph nodes are involved in a minority of cases, usually as a result of direct invasion rather than hematogenous spread.
**Option B:** While some soft tissue sarcomas may express certain surface antigens, they do not typically spread through direct cell-to-cell contact. This mode of spread is more characteristic of carcinomas, such as breast or colon cancer.
**Option C:** Direct invasion through contiguous tissue planes is a common feature of soft tissue sarcomas, but it is not the primary mode of spread. Hematogenous dissemination via the bloodstream is the main mechanism of metastasis for these tumors.
**Clinical Pearl / High-Yield Fact**
Soft tissue sarcomas often present with a characteristic "sunburst" or "spiculated" pattern on imaging studies, reflecting their rapid growth and expansion into surrounding tissues.
**Correct Answer:** D.