Demodicosis is a rare condition that most often occurs in immunocompromised patients. We here describe a boy with T-cell non-Hodgkin lymphoma who developed a facial papulopustular eruption just before finalizing T-cell non-Hodgkin lymphoma treatment. He was treated for several infectious diseases without improvement. Demodicosis was considered and complete resolution was finally reached with topical metronidazole. We conducted a systematic search of all previously described cases of this condition in children with cancer, which showed that almost all demodicosis cases occurred in patients with lymphoreticular malignancies during maintenance chemotherapy. Hence, demodicosis may be seriously considered in antibiotic-resistant facial papulopustular eruptions in this group of patients to prevent delay of adequate treatment.