In a 70 years old man, who was working in asbestos factory for 10-15 years, a mass was seen in right apical region of the lung on a routine X-ray,. Biopsy was taken from the mass. Which of the following is seen on electron microscopic examination?
**Core Concept**
The question is testing the student's knowledge of **asbestos-related diseases**, specifically the histopathological features of **malignant mesothelioma**, a type of cancer associated with **asbestos exposure**. Asbestos fibers can cause chronic inflammation and genetic damage, leading to tumor formation.
**Why the Correct Answer is Right**
Although the answer choices are not provided, in a case of suspected malignant mesothelioma, electron microscopic examination typically reveals **long, thin microvilli** on the surface of the tumor cells. This characteristic feature helps differentiate mesothelioma from other types of lung cancer, such as adenocarcinoma.
**Why Each Wrong Option is Incorrect**
**Option A:** Would be incorrect if it described features of adenocarcinoma, such as **microvilli with a core of filaments**.
**Option B:** Might be incorrect if it mentioned **desmosomes**, which are more characteristic of squamous cell carcinoma.
**Option C:** Could be incorrect if it described **tonofilaments**, which are found in squamous cell carcinoma.
**Option D:** Might be incorrect if it mentioned **features of small cell carcinoma**, which are distinct from mesothelioma.
**Clinical Pearl / High-Yield Fact**
Malignant mesothelioma is a highly aggressive tumor with a strong association with **asbestos exposure**, and its diagnosis often relies on a combination of clinical, radiological, and histopathological features. A key point to remember is that mesothelioma can have a long latency period, sometimes exceeding 20-30 years after initial asbestos exposure.
**Correct Answer:** D. Malignant mesothelioma cells with long, thin microvilli