Hyperleucocytosis following G-CSF treatment for sulfasalazine-induced agranulocytosis

Agranulocytosis is a rare but serious adverse effect of sulfasalazine treatment. We present a case of a 51-year-old woman receiving sulfasalazine for inflammatory arthritis presenting with sore throat, fever, lethargy and leucopenia (white cell count 0.9 × 10(9)/L). After 9 days of treatment with filgrastim (granulocyte-colony stimulating factor, G-CSF), her white cell count increased to 77.4 × 10(9)/L. This case highlights the importance of recognising sulfasalazine-induced agranulocytosis and the management of hyperleucocytosis following G-CSF treatment, to prevent harmful sequelae.