Pulmonary alveolar proteinosis as a terminal complication in a case of myelodysplastic syndrome with idic(20q-).

Secondary pulmonary alveolar proteinosis (PAP) is a rare lung disease that has been reported in 13 cases of myelodysplastic syndromes (MDS). A dicentric isochromosome of deleted chromosome 20q, idic(20q-), is a newly recognized rare, but recurrent, cytogenetic anomaly that has been described in 28 cases of MDS. Recently, we encountered an interesting MDS patient with idic(20q-) and secondary PAP. At presentation, she was a 40-year-old woman with pancytopenia and dysplasia involving 2 cell lineages that were compatible with refractory cytopenia with multilineage dysplasia. A chromosome analysis of bone marrow cells using the R-banding technique revealed a karyotype of 46,XX,-20 and +a small metacentric marker chromosome. Fluorescence in situ hybridization demonstrated this marker chromosome to be idic(20q-). Three years after presentation, her disease was complicated by secondary PAP that was confirmed by chest computed tomographic scans and a thoracoscopic lung biopsy, revealing the characteristic periodic acid Schiff stain-positive materials filling the alveoli. The patient subsequently died of respiratory failure 45 months after diagnosis. To our knowledge, this is the first MDS patient with idic(20q-) and secondary PAP to be reported in the literature. Moreover, this patient is also the 29th MDS case with idic(20q-).