• Coagulative Necrosis Definition: Coagulative necrosis is the form of tissue death typically resulting from sudden ischemia or infarction (in all solid visceral organs except the brain).
• Histopathological Characteristics: Characterized by the denaturing of structural proteins and enzymatic proteins alike, preventing autolytic dissolution. While cellular structural details are lost (nuclei undergo pyknosis, karyorrhexis, and karyolysis), the basic architectural outline ('tombstone' appearance or ghost framework) of the tissue is preserved for several days until infiltrated by phagocytes.

Correct option: (3) Coagulative necrosis

• Pathology of Brown Induration of the Lung: Brown induration is the pathognomonic macroscopic and microscopic appearance of the lungs during chronic passive pulmonary congestion, commonly secondary to left-sided heart failure (e.g., mitral valve insufficiency or cardiomyopathy).
• Mechanism & Hemosiderosis: Elevated pulmonary venous pressure forces erythrocytes to extravasate into alveolar spaces. Alveolar macrophages engulf the extravasated RBCs and digest hemoglobin into insoluble golden-brown hemosiderin pigments (hemosiderosis / 'heart failure cells'). Concurrent chronic hypoxia stimulates interstitial fibroblastic proliferation, making the lungs firm, heavy, and russet-brown (brown induration).

Correct option: (4) Haemosiderosis

• Cytological Sampling of Deep Viscera: Fine Needle Aspiration Cytology (FNAC)—typically performed percutaneously under real-time ultrasound or CT guidance using a slender 21 to 25 gauge needle attached to a syringe—is the gold standard diagnostic technique for collecting cytological samples from deep-seated visceral organs (such as liver, spleen, kidneys, pancreas, and deep lymph nodes).
• Advantages: Highly minimally invasive, requires minimal sedation, avoids major surgical laparotomy, and yields diagnostic cellular harvests with minimal hemorrhage risk.
• Other Cytology Techniques: Impression smears, scrapings, and swabs are used exclusively for external cutaneous masses, mucosal surfaces, or excised surgical biopsy specimens.

Correct option: (3) Fine needle aspiration cytology (FNAC)