Evaluating for GM-CSF autoantibodies is essential for distinguishing autoimmune and secondary forms of pulmonary alveolar proteinosis (PAP), even in cases involving hematologic malignancy, according to researchers at the Ogaki Municipal Hospital in Japan.
The researchers present the case of a 69-year-old man with autoimmune PAP and a simultaneous diagnosis of myeloproliferative neoplasm (MPN) in Internal Medicine. The case demonstrates that evaluating the levels of GM-CSF autoantibodies can be critical for distinguishing secondary and autoimmune PAP.
The researchers reported that the patient’s MPN progressed to acute myeloid leukemia within 24 months of the 2 diagnoses, with eventual death due to an alveolar hemorrhage during remission induction chemotherapy. They found no progression of the patient’s PAP even with the progression of MPN to leukemia.
PAP is categorized as genetic, secondary, or autoimmune. Previous studies have shown that blood disorders can cause secondary PAP possibly due a deficiency of GM-CSF and related macrophage dysfunction. However, the researchers note that autoimmune PAP is believed to be primarily due to anti-GM-CSF autoantibodies.
The patient in this case was positive for GM-CSF autoantibodies. Furthermore, the lack of PAP progression after MPN progression to acute myeloid leukemia is consistent with autoimmune PAP. To date, few reports of autoimmune PAP with hematologic malignancy have been reported. However, based on their experience with this case, the researchers conclude that examining levels of GM-CSF autoantibodies is critical for distinguishing PAP as autoimmune or secondary, even when the patient has PAP with hematologic disease.
1. Imoto N, Harunori N, Furukawa K, et al. GM-CSF autoantibody-positive pulmonary alveolar proteinosis with simultaneous myeloproliferative neoplasm. Intern Med. 2017;56:435-439.