Which of the following statements about chronic osteomyelitis is false?
Calcified pulmonary metastasis is seen in which carcinoma?
Lendrum's stain is done for:
Virchow method of organ removal is:
NEET-PG 2013 - Pathology NEET-PG Practice Questions and MCQs
Question 71: Which of the following statements about chronic osteomyelitis is false?
- A. Reactive new bone formation
- B. Cloaca is an opening in involucrum
- C. Involucrum is dead bone (Correct Answer)
- D. Sequestrum is hard and dense
Explanation: ***Involucrum is dead bone*** - This statement is false because the **involucrum** is the layer of **new bone formation** that surrounds a segment of necrotic (dead) bone, known as the **sequestrum**, in chronic osteomyelitis [1]. - The involucrum represents the body's attempt to wall off the infection and dead bone, and thus, it is living, *reactive bone*, not dead bone [1]. *Reactive new bone formation* - This statement is true; **reactive new bone formation** occurs around infected or necrotic bone in chronic osteomyelitis, forming the **involucrum** [1]. - This process is a hallmark of the body's response to chronic infection and attempts to contain it. *Cloaca is an opening in involucrum* - This statement is true; a **cloaca** is a **fistulous tract** or opening in the **involucrum** that allows pus and necrotic debris from the infected area to drain to the skin surface. - This drainage is a common clinical sign of chronic osteomyelitis. *Sequestrum is hard and dense* - This statement is true; the **sequestrum** is a piece of **necrotic (dead) bone** that has become separated from living bone due to ischemia and infection [1]. - Due to the loss of blood supply and avascular necrosis, it appears **dense, hard, and radiodense** on imaging, representing devitalized bone tissue that is walled off from the body's immune response. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1197-1198.
Question 72: Calcified pulmonary metastasis is seen in which carcinoma?
- A. Pancreatic carcinoma
- B. Thyroid carcinoma (Correct Answer)
- C. Endometrial carcinoma
- D. None of the options
Explanation: ***Thyroid carcinoma*** - **Papillary** and **medullary thyroid carcinomas** can produce **calcified pulmonary metastases**. - In **papillary thyroid cancer**, calcification occurs due to **psammoma bodies** (concentrically laminated calcified structures). - In **medullary thyroid cancer**, calcification can occur through **dystrophic calcification** within the tumor tissue. - Other common causes of calcified lung metastases include **osteosarcoma** and **chondrosarcoma**. *Pancreatic carcinoma* - Pancreatic carcinoma rarely causes **calcified pulmonary metastases**; metastatic lesions are typically **non-calcified**. - Metastases are more commonly found in the **liver** and **peritoneum**. - Primary pancreatic tumors may show calcification, but metastases usually do not. *Endometrial carcinoma* - Endometrial carcinoma metastases to the lungs are usually **non-calcified** and appear as **soft tissue nodules**. - While it can metastasize to the lungs, **calcification** is not a typical feature of its pulmonary spread. *None of the options* - This option is incorrect because **thyroid carcinoma** (particularly papillary type) is a well-recognized cause of **calcified pulmonary metastases**. - Among epithelial malignancies, thyroid carcinoma is one of the classic causes of this finding.
Question 73: Lendrum's stain is done for:
- A. Air embolism
- B. Pulmonary embolism
- C. Fat embolism
- D. Amniotic fluid embolism (Correct Answer)
Explanation: ***Amniotic fluid embolism*** - **Lendrum's stain** (MSB - Martius Scarlet Blue) is specifically used to identify **fibrin**, **mucin**, and **squamous cells** in the pulmonary vasculature, which are characteristic findings in amniotic fluid embolism. [1] - This stain excellently demonstrates **fibrin** (stains red) and helps visualize components of amniotic fluid that embolize to the mother's lungs, leading to a severe, often fatal, obstetric emergency. [1] - Lendrum's method is particularly valuable in forensic pathology and autopsy diagnosis of this condition. *Air embolism* - Air embolism diagnosis relies on identifying **air bubbles** in the cardiovascular system, often confirmed by imaging studies or direct visualization during autopsy. [1] - Special stains are not typically used for direct detection of air in tissue sections. *Pulmonary embolism* - Pulmonary embolism, typically caused by a **blood clot**, is diagnosed by identifying **fibrin** and **red blood cells** within pulmonary arteries, often with stains like hematoxylin and eosin (H&E). [1] - While Lendrum's stain can demonstrate fibrin, it is specifically employed when amniotic fluid embolism is suspected, not for routine thromboembolic disease. *Fat embolism* - **Fat embolism** is diagnosed by demonstrating **fat globules** in the pulmonary microvasculature using **fat stains** like **Oil Red O** or **Sudan Black**, usually on frozen sections. - Lendrum's stain does not specifically highlight fat emboli. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 322-324.
Question 74: Virchow method of organ removal is:
- A. In situ dissection
- B. Organs removed en masse
- C. Organs removed en bloc
- D. Organs removed one by one (Correct Answer)
Explanation: ***Organs removed one by one*** - The **Virchow method** is characterized by the sequential removal of **individual organs** through a systematic dissection. - This technique allows for detailed inspection and measurement of each organ independently, which can be useful for identifying specific pathologies confined to single structures. *In situ dissection* - This method involves dissecting and examining organs **within the body cavity before removal**, which is not the primary characteristic of the Virchow method. - While some dissection occurs *in situ*, the essential principle of Virchow's method is the **separate extraction** of organs. *Organs removed en masse* - This describes the **Ghon method**, where organs are removed in three blocks (thoracic, abdominal-gastrointestinal, and genitourinary) and then dissected. - This method aims to preserve anatomical relationships between organs, which contrasts with the single-organ focus of the Virchow method. *Organs removed en bloc* - This term generally refers to removing organs in **several blocks or groups** (similar to the Ghon method), maintaining some anatomical connections. - It does not involve the individual removal of each organ, which is the defining feature of the Virchow technique.