Case presentation An 11-week-old infant was presented with asymmetrical acute flaccid paralysis and reduced muscle tone in lower limbs. Medical history Vaginal delivery with 3.15 kg birthweight All timely vaccinations His mother had 7 previous first-trimester miscarriages Mother found to be HIV positive during this pregnancy The infant received zidovudine for 6 weeks and nevirapine for 12 weeks The infant is HIV negative The infant is positive for X-linked agammaglobulinemia Investigation findings Muscle power was as follows – Lower limbs – 0/5 Right upper limb – 3/5 Proximal left upper limb – 0/5 Distal left upper limb – 2/5 What is your diagnosis?

Amyotrophic lateral sclerosis Vaccine-derived poliomyelitis B-cell lymphoma Myasthenia gravis (Answer is posted in the comment section below!) *This Case Challenge is from the Editorial Team of Docplexus and is meant for educational purposes…