Uneventful outcome of unrelated hematopoietic stem cell transplantation in a patient with leukemic transformation of Kostmann syndrome and long-lasting invasive pulmonary mycosis

Kostmann syndrome (KS) is an inherited hematological disorder characterized by an absolute neutrophil count (ANC) <0.2 x 10 9 /L and life-threatening bacterial infections. Granulocyte-colony stimulating factor (G-CSF) makes it possible to reach an ANC of 1.0 x 10 9 /L and consequently to reduce significantly the occurrence of severe infections. Absence of response to G-CSF, G-CSF receptor mutation, and leukemic transformation are absolute indications to perform hematopoietic stem cell transplantation (HSCT). Pulmonary mycosis does not represent an absolute contraindication to bone marrow transplantation (BMT), although a relapse rate of 30-50% has been reported, despite adequate medical and surgical treatment. Mycotic pneumonia recurrence shows a mortality rate above 80%, especially in the presence of persisting immunosuppression. We report on a KS patient with long-lasting fungal pneumonia who developed myelodysplasia and subsequent acute myeliod leukemia (AML) conversion resistant to antiblastic therapy. Despite surgical excision and secondary prophylaxis, recurrence of the pulmonary lesion occurred prior to the unrelated HSCT. In spite of these poor prognostic characteristics, outcome was uneventful and the patient is alive and well in continuous complete remission with no signs of fungal infection.