[Dactylitis, early onset of drepanocytosis and a predictor of a poor prognosis].

Sickle cell disease is an inherited monogenic disease. The most frequent form is due to a homozygous mutation in the S allele that encodes haemoglobin S. Its clinical course, while highly variable, is characterised by chronic haemolytic anaemia and vaso-occlusive events leading to early multiorgan failure. We present the case of a 7-month-old infant who was brought to the emergency department because of swelling in the left hand, with no evidence of preceding trauma, preserved spontaneous movement and no fever. The family was from Equatorial Guinea and the patient had resided in Spain since birth. The pregnancy, delivery and neonatal period had passed without complications. The patient was up to date with the routine immunisation schedule and had not been vaccinated against pneumococcus. There was no family history of interest. The physical examination showed that the patient was stable, with appropriate anthropometric values and vital signs. He had swelling in the dorsal aspect of the left hand that was tender to palpation, with no other signs of inflammation; examination of the remaining organ systems was normal. An initial radiographic examination (Fig. 1) revealed a periostic reaction at the fifth metacarpal bone. At this point, the differential diagnosis included bone tumour, osteomyelitis and bone infarction in the context of sickle cell disease. Laboratory analyses revealed a regenerative microcytic anaemia (haemoglobin [Hb]: 8.6 g/dL, mean cell volume 70 fL, reticulocytes 7.4%), with normal values for the rest of the complete blood count; normal coagulation,