Which of the following is not a malignant tumour ?

Options

A. Adenocarcinoma
B. Osteoma
C. Angiosarcoma
D. Melanoma

Answer

To determine which of the following is not a malignant tumor, we need to understand the characteristics of malignant tumors and the specific types of tumors mentioned in the options.

### Step 1: Understand Malignant Tumors
Malignant tumors are cancerous growths that have the ability to invade surrounding tissues and spread to other parts of the body through a process known as metastasis. They can lead to serious health issues and are often life-threatening.

### Step 2: Analyze the Options
1. **Adenocarcinoma**: This is a type of cancer that forms in mucus-secreting glands and is considered a malignant tumor.
2. **Osteoma**: This is a benign tumor that forms in bone tissue and does not have the properties of malignancy; it does not metastasize.
3. **Angiosarcoma**: This is a malignant tumor that arises from blood vessels and is known for its aggressive nature.
4. **Melanoma**: This is a malignant tumor of melanocytes, the cells that produce pigment in the skin, and is also known for its ability to metastasize.

### Step 3: Identify the Non-Malignant Tumor
From the analysis of the options, we can see that:
- Adenocarcinoma, angiosarcoma, and melanoma are all malignant tumors.
- Osteoma is the only tumor listed that is not malignant.

### Conclusion
The tumor that is not malignant is **Osteoma**. Therefore, the correct answer is option number two.

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