Sciatic nerve injury after inadvertent intramuscular gluteal injection is a well-described entity. We have presented a case of a rare and probably underdiagnosed pathological entity, Nicolau syndrome, which can be confused with injection palsy.We report the case of a 13-year-old boy who had presented with foot drop and urinary and fecal incontinence after an intramuscular injection of benzathine penicillin in the left gluteal region. On examination, the patient had multiple ecchymoses over the left gluteal region and back of the thigh, mild swelling of the left lower limb, and left foot drop. Meticulous examination also revealed a subtle weakness of the opposite limb. Nerve conduction studies revealed axonopathy involving multiple bilateral lower limb nerves. These unusual neurological-dermatological signs and electrophysiological findings raised the concern for an alternative pathology, which was later diagnosed as Nicolau syndrome. The patient experienced clinical and electrophysiological recovery after a course of oral steroids and physiotherapy during the next few months.Before diagnosing injection sciatic nerve injury, the possibility of medically treatable Nicolau syndrome should be considered. Neurosurgeons' familiarity with this pathology and a timely diagnosis is essential to plan appropriate treatment strategies.