A 26‐month‐old male presented with bone marrow failure and dystrophic nail lesions mimicking onychomycosis. There was no skin finding. Treatment with androgen and methylprednisolone was started due to unavailability of a matched‐related hematopoietic stem cell donor. After 30 months, transfusion support was required. TINF2 mutation was identified at the age of five and dyskeratosis congenita (DC) was confirmed. TIN2 mutation analysis must be carried out in patients younger than 10 years presenting with bone marrow failure even if characteristic physical anomalies of DC is missing. Genetic confirmation of DC prevents ineffective immunotherapy with misdiagnosis of acquired aplastic anemia. Pediatr Blood Cancer. 2010;55:1185–1186. © 2010 Wiley‐Liss, Inc.