**Question:** Excessive fibrosis in tumor is called

A. Desmoplasia
B. Stromal overgrowth
C. Fibrosis
D. Hypoxia

**Core Concept:** Fibrosis is the excessive deposition of extracellular matrix proteins, primarily collagen, leading to tissue stiffening and loss of function. Desmoplasia refers to the proliferation of fibroblasts and collagen fibers within a tumor, contributing to its increased stiffness and altered cellular behavior.

**Why the Correct Answer is Right:** In the context of tumors, excessive fibrosis is often associated with tumor desmoplasia (A) - a process characterized by the proliferation of fibroblasts and collagen fibers within the tumor mass. This leads to an increase in fibrous tissue, making the tumor stiffer and altering its cellular behavior.

**Why Each Wrong Option is Incorrect:**

- B. Stromal overgrowth: While the term "stromal overgrowth" is related, it does not directly describe excessive fibrosis in tumors.
- C. Fibrosis: Fibrosis is the excessive deposition of collagen, but does not specifically refer to the tumor microenvironment.
- D. Hypoxia: Hypoxia is a condition of low oxygen levels, which is related but not directly describing excessive fibrosis within the tumor.

**Clinical Pearl:** Desmoplasia plays a significant role in tumor progression, as it can lead to increased resistance to chemotherapy and radiation therapy, as well as influencing tumor cell invasion and angiogenesis. Understanding desmoplasia can aid in developing targeted therapies to combat tumor growth and progression.

**Correct Answer:** A. Desmoplasia