Mesothelioma Navy Mesothelioma Diagnosis & Treatment 4 — Questions and Answers
Question 1: A Navy veteran's pleural biopsy shows cells staining positive for calretinin, WT-1, and CK5/6, but negative for TTF-1 and CEA. What is the most likely diagnosis?
- Squamous cell carcinoma of the lung
- Lung adenocarcinoma
- Epithelioid mesothelioma (Correct answer)
- Metastatic colorectal carcinoma
Correct answer: Epithelioid mesothelioma
The immunoprofile (calretinin+, WT-1+, CK5/6+, TTF-1−, CEA−) is characteristic of epithelioid mesothelioma, not lung carcinoma.
Question 2: What does the term 'malignant pleural effusion' mean in the setting of mesothelioma?
- Benign fluid accumulation caused by heart failure in a mesothelioma patient
- Fluid in the pleural space containing malignant cells shed by the tumor (Correct answer)
- Blood in the pleural space from a surgical complication
- Air trapped in the pleural space by tumor obstruction
Correct answer: Fluid in the pleural space containing malignant cells shed by the tumor
Malignant pleural effusion contains cancerous cells and is a common presenting feature of pleural mesothelioma, causing dyspnea and chest heaviness.
Question 3: Which genetic mutation, involving a tumor suppressor gene, is the most common somatic alteration found in mesothelioma?
- KRAS mutation
- BAP1 loss (Correct answer)
- EGFR exon 19 deletion
- ALK rearrangement
Correct answer: BAP1 loss
BAP1 (BRCA1-associated protein 1) loss is the most frequently identified somatic alteration in mesothelioma and is also linked to hereditary predisposition.
Question 4: During a thoracentesis for mesothelioma diagnosis, the cytology returns 'atypical mesothelial cells.' What should the next diagnostic step typically be?
- Start chemotherapy immediately based on this result
- Proceed with image-guided or surgical pleural biopsy for definitive tissue diagnosis (Correct answer)
- Repeat the thoracentesis in 3 months
- Perform a bone marrow biopsy
Correct answer: Proceed with image-guided or surgical pleural biopsy for definitive tissue diagnosis
Atypical cytology is insufficient for a definitive mesothelioma diagnosis; a tissue biopsy providing histologic architecture and immunohistochemistry is required.
Question 5: What is 'hemithoracic radiation' and when is it used in mesothelioma management?
- Low-dose radiation to both sides of the chest for symptom control
- High-dose radiation to one entire side of the chest, typically after EPP to reduce local recurrence (Correct answer)
- Targeted brachytherapy seeds placed in the pleural space
- Prophylactic port-site radiation after diagnostic procedures
Correct answer: High-dose radiation to one entire side of the chest, typically after EPP to reduce local recurrence
Hemithoracic radiation delivers high doses to the entire affected side of the chest and is used postoperatively after EPP as part of a multimodal approach.
Question 6: What does 'epithelioid' mesothelioma mean histologically, and why does it matter for prognosis?
- Cells resembling endothelium; associated with vascular invasion and worst prognosis
- Cells with epithelial-like morphology; associated with best prognosis among the three subtypes (Correct answer)
- Cells forming glandular structures; unresponsive to all therapy
- Cells indistinguishable from sarcoma; intermediate prognosis
Correct answer: Cells with epithelial-like morphology; associated with best prognosis among the three subtypes
Epithelioid mesothelioma has cells resembling epithelial tissue and carries the best prognosis, with median survival typically exceeding that of sarcomatoid or biphasic disease.
Question 7: A veteran with mesothelioma is enrolled in a clinical trial testing a VEGF inhibitor combined with standard chemotherapy. What biological process does VEGF inhibition target?
- DNA repair in tumor cells
- Tumor angiogenesis (formation of new blood vessels feeding the tumor) (Correct answer)
- T-cell checkpoint suppression
- Folate metabolism within cancer cells
Correct answer: Tumor angiogenesis (formation of new blood vessels feeding the tumor)
VEGF (vascular endothelial growth factor) promotes angiogenesis, and inhibiting it starves the tumor of the blood supply it needs to grow.
Mesothelioma Navy Mesothelioma Diagnosis & Treatment 4
A Navy veteran's pleural biopsy shows cells staining positive for calretinin, WT-1, and CK5/6, but negative for TTF-1 and CEA.
What is the most likely diagnosis?