PA10.1-5,PA11.1-3,PA12.1-3 | Infections, Genetic & Environmental Disease — Practice Quiz

A 9-year-old boy from rural Odisha presents with fever, headache, and altered sensorium for 2 days. His mother reports he had rigors 3 days ago. On examination: GCS 8/15, temperature 39.8°C, no neck stiffness, fundus shows retinal haemorrhages. Peripheral blood smear shows ring-form trophozoites within erythrocytes with multiple rings per cell and 'appliqué' (accolé) forms at the cell margin. What is the most likely diagnosis?

A 32-year-old labourer from Tamil Nadu presents with a 2 cm hypoaesthetic pale patch on his left forearm and thickening of the left ulnar nerve. Slit-skin smear is negative. Skin biopsy shows epithelioid cell granulomas with Langhans giant cells, dense lymphocytic cuffing, and perineural infiltration; no acid-fast bacilli are seen on Fite-Faraco stain. Which immunological finding best explains this histology?

A 19-year-old college student from Himachal Pradesh presents with recurrent seizures starting at age 17. MRI brain shows multiple ring-enhancing cystic lesions in the cerebral cortex and basal ganglia, several with a central hyperintense scolex (dot). The lesions show surrounding oedema and enhancement. What is the tissue reaction seen histologically around viable cysts?

A 55-year-old diabetic man is admitted to the ICU with severe COVID-19 pneumonia. He is intubated on day 3. Autopsy (if performed) of fatal early COVID-19 pneumonia would most characteristically show which pulmonary pathological finding?

A 2-year-old boy is brought with developmental delay, upward-slanting palpebral fissures, a single palmar crease, and a ventricular septal defect detected on echocardiography. His karyotype is reported as 47,XY,+21. Which mechanism most commonly underlies this chromosomal abnormality?

A 16-year-old girl is referred for primary amenorrhoea. She is 148 cm tall with a webbed neck, widely-spaced nipples, and shield-shaped chest. Breast development is Tanner stage 1. Echocardiography reveals a bicuspid aortic valve. Her karyotype is 45,X. Which additional laboratory finding would you most expect?

A 4-year-old boy presents with a rapidly enlarging right flank mass discovered by his mother during bathing. CT abdomen shows a large heterogeneous intrarenal mass with areas of necrosis, displacing — but not invading — adjacent bowel. The mass has both epithelial and mesenchymal components on biopsy, with embryonic blastema, tubules, and stromal elements. What is the most likely diagnosis?

A 6-month-old Ashkenazi Jewish infant presents with progressive neurological deterioration, hyperacusis, and a cherry-red spot on fundoscopy. The parents are non-consanguineous. Enzyme assay confirms deficiency of hexosaminidase A. Which storage material accumulates intracellularly?

A 55-year-old male smoker of 30 pack-years presents with a chronic cough and haemoptysis. Bronchoscopy reveals a central endobronchial mass; biopsy shows sheets of large cells with abundant pink cytoplasm, intercellular bridges, and keratin pearls. What is the most common mechanism by which cigarette smoke causes this malignancy?

A 3-year-old child in a refugee camp presents with pitting oedema of the legs, a 'flaky-paint' skin rash, thin discoloured hair (flag sign), and a markedly protuberant abdomen. Weight-for-height Z-score is –2.5. Serum albumin is 1.8 g/dL. The child is alert and preserves subcutaneous fat. What is the diagnosis and the primary pathophysiological mechanism?

A 4-year-old child from a low-income household presents with night blindness (nyctalopia) and small, triangular, silvery-white foamy plaques on the nasal and temporal conjunctiva bilaterally. The cornea appears dull and hazy. Which vitamin deficiency does this represent, and which corneal complication, if untreated, is most dreaded?

A 35-year-old man with a BMI of 34 kg/m² attends a metabolic health clinic. His investigations show: fasting plasma glucose 6.3 mmol/L, waist circumference 98 cm, triglycerides 2.1 mmol/L, HDL-cholesterol 0.9 mmol/L, and blood pressure 138/88 mmHg. He is not on any medication. According to IDF/NCEP-ATP III harmonised criteria, how many metabolic syndrome components does he satisfy, and what is the threshold waist circumference for South Asian men?