General Pathology: Cellular Injury, Degeneration, Necrosis, Gangrene, Calcification & Cell Death

Anthracosis is an environmental pneumoconiosis characterized by the asymptomatic inhalation and deposition of exogenous carbon or coal dust particles in pulmonary alveolar macrophages and peribronchial lymph nodes. Siderosis is iron dust deposition, silicosis is silica inhalation, and plumbism is chronic lead poisoning.

Clostridium perfringens produces potent histotoxic exotoxins (such as alpha-toxin, a lecithinase/phospholipase C, and theta-toxin, a pore-forming cytolysin):

• Abscess formation is characteristic of pyogenic bacteria like Trueperella pyogenes or Staphylococcus aureus.
• Epidermolysis bullosa is a blistering cutaneous disorder.
• Shock is an end-stage hemodynamic collapse, not a primary local histopathological tissue lesion.
• In gas gangrene (malignant edema/clostridial myonecrosis), toxins cause extensive liquefactive and coagulative necrosis of skeletal muscle fibers and connective tissue, accompanied by carbohydrate fermentation that produces gaseous crepitation in affected tissues.

Features defining necrosis versus apoptosis:

• False: Apoptosis is the programmed physiological form of cell turnover; necrosis is strictly non-physiological.
• True: Necrosis is invariably a pathological process triggered by severe cellular injury such as hypoxia, toxins, trauma, or microbial invasion.
• True: Necrosis is characterized by passive, unregulated cell swelling (oncosis), membrane rupture, and leakage of lysosomal contents.
• True: Because necrosis releases intracellular damage-associated molecular patterns (DAMPs) that incite destructive inflammation, it is always harmful to the host organism.

Sexual dimorphism in blood flukes (Schistosoma species):
Statement (I) is true: Schistosomes are dioecious trematodes. The male is shorter and stouter (approx. 10-15 mm), whereas the female is longer, slender, and cylindrical (approx. 15-26 mm).
Statement (II) is false: The ventral lateral margins of the male fold inward to form the gynaecophoric canal, in which the male carries the female during copulation; the female does not carry the male.