Epithelial/Connective tissues — MCQs

A 3-month-old infant presents with severe joint hypermobility, skin hyperextensibility, and delayed wound healing. Skin biopsy shows abnormal collagen fibril organization with irregular diameter and reduced tensile strength. Genetic testing reveals a mutation affecting lysyl hydroxylase, an enzyme involved in collagen post-translational modification. The family asks about prognosis and potential complications. Synthesize the biochemical defect with clinical manifestations to determine the most critical pathophysiological mechanism.

A 58-year-old woman undergoes cervical biopsy following an abnormal Pap smear. Histology shows full-thickness epithelial atypia with loss of cellular polarity, increased nuclear-to-cytoplasmic ratio, and numerous mitotic figures, but the basement membrane remains intact. Her oncologist discusses treatment options. The patient is concerned about progression risk versus overtreatment. Evaluate the most appropriate management strategy considering the tissue diagnosis and natural history.

A 42-year-old woman with Marfan syndrome presents to the emergency department with acute chest pain. CT angiography reveals a Type A aortic dissection. The cardiothoracic surgeon explains that her underlying connective tissue disorder predisposed her to this complication. During surgery, the aortic wall appears thin and fragile. Evaluate which molecular defect best explains the compromised structural integrity of her aortic wall.

A 67-year-old man undergoes tracheal reconstruction following long-term intubation injury. The surgeon explains that the graft must replicate the normal tracheal epithelium to maintain proper mucociliary clearance. Biopsy of normal trachea shows tall columnar cells with cilia, interspersed goblet cells, and small basal cells, all appearing to reach the basement membrane at different levels. Analyze which histological feature is most critical for proper graft function.

A 4-year-old boy presents with multiple bone fractures from minor trauma, blue sclerae, and hearing loss. Genetic testing reveals a COL1A1 mutation affecting type I collagen synthesis. Bone biopsy shows thin, disorganized collagen fibrils. His parents ask about the prognosis and potential complications. Analyze the relationship between the molecular defect and clinical manifestations.