Clinical approach for pulmonary alveolar proteinosis in children

In this editorial, we discuss the clinical implications of the article by Zhang et al. Pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by excessive surfactant accumulation in the alveoli. It is classified into four categories: Primary, secondary, congenital, and unclassified forms. Primary PAP is caused by the disruption of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor signaling, which is necessary for the clearance of surfactant by alveolar macrophages. It is further divided into autoimmune PAP, caused by anti-GM-CSF antibodies blocking alveolar macrophage activation, and hereditary PAP, resulting from mutations in genes encoding GM-CSF receptors. Secondary PAP develops due to conditions affecting the number or function of alveolar macrophages, such as infections, immunodeficiency, hematological disorders, or exposure to inhaled toxins. Congenital PAP is linked to mutations in genes involved in surfactant protein production. Notably, the causes of PAP differ between children and adults. Diagnostic features include a characteristic "crazy-paving" pattern on high-resolution computed tomography, accompanied by diffuse ground-glass opacities and interlobular septal thickening. The presence of PAP can be identified by the milky appearance of bronchoalveolar lavage fluid and histological evaluation. However, these methods cannot definitively determine the cause of PAP. Whole lung lavage remains the standard treatment, often combined with specific therapies based on the underlying cause.

Autoimmune Pulmonary Alveolar Proteinosis Complicated by Myelodysplastic Syndrome

Pulmonary alveolar proteinosis (PAP) is characterized by an abnormal surfactant accumulation in peripheral air spaces. Autoimmune PAP (APAP) results from macrophage dysfunction caused by anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies, and the presence of antibodies more than the cutoff value is specific for APAP. In contrast, secondary PAP (SPAP) does not require anti-GM-CSF autoantibodies and is complicated by other diseases, including myelodysplastic syndrome (MDS). A 73-year-old man with anemia and thrombocytopenia was diagnosed with APAP and MDS simultaneously. The measurement of serum anti-GM-CSF autoantibodies is important for the correct diagnosis and management of PAP, even with an established diagnosis of underlying SPAP-suggestive disease.

A case of autoimmune pulmonary alveolar proteinosis during the course of treatment of rapidly progressive interstitial pneumonia associated with anti-MDA5 antibody-positive dermatomyositis

BACKGROUND

Autoimmune pulmonary alveolar proteinosis (APAP) is a diffuse lung disease that causes abnormal accumulation of lipoproteins in the alveoli; however, its pathogenesis remains unclear. Recently, APAP cases have been reported during the course of dermatomyositis. The combination of these two diseases may be coincidental; however, it may have been overlooked because differentiating APAP from a flare-up of interstitial pneumonia associated with dermatomyositis is challenging. This didactic case demonstrates the need for early APAP scrutiny.

CASE PRESENTATION

A 50-year-old woman was diagnosed with anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody-positive dermatitis and interstitial pneumonia in April 2021. The patient was treated with corticosteroids, tacrolimus, and cyclophosphamide pulse therapy for interstitial pneumonia complicated by MDA5 antibody-positive dermatitis, which improved the symptoms and interstitial pneumonia. Eight months after the start of treatment, a new interstitial shadow appeared that worsened. Therefore, three additional courses of cyclophosphamide pulse therapy were administered; however, the respiratory symptoms and interstitial shadows did not improve. Respiratory failure progressed, and 14 months after treatment initiation, bronchoscopy revealed turbid alveolar lavage fluid, numerous foamy macrophages, and numerous periodic acid-Schiff-positive unstructured materials. Blood test results revealed high anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody levels, leading to a diagnosis of APAP. The patient underwent whole-lung lavage, and the respiratory disturbance promptly improved. Anti-GM-CSF antibodies were measured from the cryopreserved serum samples collected at the time of diagnosis of anti-MDA5 antibody-positive dermatitis, and 10 months later, both values were significantly higher than normal.

CONCLUSIONS

This is the first report of anti-MDA5 antibody-positive dermatomyositis complicated by interstitial pneumonia with APAP, which may develop during immunosuppressive therapy and be misdiagnosed as a re-exacerbation of interstitial pneumonia. In anti-MDA5 antibody-positive dermatomyositis, APAP comorbidity may have been overlooked, and early evaluation with bronchoalveolar lavage fluid and anti-GM-CSF antibody measurements should be considered, keeping the development of APAP in mind.

HLA-DRB1*14:54 Is Associated with Pulmonary Alveolar Proteinosis: A Retrospective Real-World Audit

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disease characterized by abnormal accumulation of pulmonary surfactant lipids in alveoli or terminal bronchioles, leading to increased infection risk and progressive respiratory failure. Approximately more than 90% of all cases are autoimmune PAP (aPAP). Since one of the predisposing factors has been identified as genes located within the major-histocompatibility-complex region, an investigation of human leukocyte antigen (HLA) alleles associated with the risk of aPAP is warranted.

METHODS

We retrospectively studied 60 patients pathologically diagnosed with PAP from 2019 to 2022. Patients were divided into the aPAP group or secondary PAP (sPAP) group according to their clinical information. Qualified DNA was extracted from the paraffin-embedded tissue of 28 patients, and the PCR-sequence-based typing method was used for HLA-DRB1 genotyping.

RESULTS

A similar HLA-DRB1 allele profile (including the HLA-DRB1*08:03) between the aPAP group and sPAP group was revealed, except that HLA-DRB1*14:54, which has never been reported in aPAP patients, was only detected in the aPAP group rather than the sPAP group (19.4% vs. 0.0%, p = 0.030). Under inhaled granulocyte-macrophage colony-stimulating factor therapy, more clinical remission was observed in HLA-DRB1*14:54 carriers rather than in HLA-DRB1*08:03 carriers (80.0% vs. 57.1%).

CONCLUSIONS

Our real-world study revealed for the first time that a population with HLA-DRB1*14:54 was subject to aPAP, and HLA-DRB1*14:54 might imply a response in aPAP patients to inhaled granulocyte-macrophage colony-stimulating factor in aPAP patients.

[Congenital pulmonary alveolar proteinosis in a neonate]

The male patient was referred to the hospital at 44 days old due to dyspnea after birth and inability to wean off oxygen. His brother died three days after birth due to respiratory failure. The main symptoms observed were respiratory failure, dyspnea, and hypoxemia. A chest CT scan revealed characteristic reduced opacity in both lungs with a "crazy-paving" appearance. The bronchoalveolar lavage fluid (BALF) showed periodic acid-Schiff positive proteinaceous deposits. Genetic testing indicated a compound heterozygous mutation in the ABCA3 gene. The diagnosis for the infant was congenital pulmonary alveolar proteinosis (PAP). Congenital PAP is a significant cause of challenging-to-treat respiratory failure in full-term infants. Therefore, congenital PAP should be considered in infants experiencing persistently difficult-to-treat dyspnea shortly after birth. Early utilization of chest CT scans, BALF pathological examination, and genetic testing may aid in early diagnosis.

Pulmonary Alveolar Proteinosis-associated Pulmonary Fibrosis: Evolutional Changes and Radiologic-Pathologic Correlation

Pulmonary alveolar proteinosis (PAP) is a rare disease with frequently favorable outcomes. In a minority of patients with primary or secondary PAP, the disease course may be complicated by pulmonary fibrosis (PF) despite appropriate management. Imaging and histopathologic manifestations of uncomplicated PAP are well-known. In contrast, radiologic-pathologic descriptions of PAP-associated PF (PAP-PF) are limited. The current manuscript presents three cases of PAP-PF, each with serial high-resolution CT imaging demonstrating the longitudinal progression of this unusual complication, with concordant pathologic findings in two patients. Much remains to be known regarding adverse prognostic factors contributing to PAP-PF. Early recognition of radiologic-pathologic manifestations would allow timely diagnosis and management optimization. Keywords: CT, Lung, Inflammation, Pathology © RSNA, 2023.

Animal models of silicosis: fishing for new therapeutic targets and treatments

Silicosis as an occupational lung disease has been present in our lives for centuries. Research studies have already developed and implemented many animal models to study the pathogenesis and molecular basis of the disease and enabled the search for treatments. As all experimental animal models used to date have their advantages and disadvantages, there is a continuous search for a better model, which will not only accelerate basic research, but also contribute to clinical aspects and drug development. We review here, for the first time, the main animal models developed to date to study silicosis and the unique advantages of the zebrafish model that make it an optimal complement to other models. Among the main advantages of zebrafish for modelling human diseases are its ease of husbandry, low maintenance cost, external fertilisation and development, its transparency from early life, and its amenability to chemical and genetic screening. We discuss the use of zebrafish as a model of silicosis, its similarities to other animal models and the characteristics of patients at molecular and clinical levels, and show the current state of the art of inflammatory and fibrotic zebrafish models that could be used in silicosis research.

Nationwide survey of adult patients with pulmonary alveolar proteinosis using the National Database of designated intractable diseases of Japan

BACKGROUND

Autoimmune pulmonary alveolar proteinosis (APAP) and congenital/hereditary PAP were labeled intractable diseases in Japan in 2015. Since then, patients registered in the National Database of Designated Incurable Diseases (NDDID) who met certain requirements became eligible for medical subsidies. Epidemiological studies using recent data are needed for the development of management protocols for patients with PAP.

METHODS

We conducted the first nationwide study describing the epidemiology and characteristics of PAP using data for patients registered in the Japanese NDDID between 2015 and 2020. We focused on patient demographics, diagnosis, disease severity score (DSS), symptoms, test results, and treatment.

RESULTS

We identified 110 patients with PAP, among whom 96.4% had APAP/idiopathic PAP (IPAP). The median age was 58 years, with a slight male predominance. Most patients had a DSS ≥3 (64.5%) and reported symptoms (e.g., dyspnea on exertion). High-resolution computed tomography typically revealed ground glass opacity and crazy paving appearances. Pulmonary function was relatively preserved, except for carbon monoxide diffusing capacity. Only 27.4% of patients underwent therapeutic whole-lung lavage and/or bronchoalveolar lavage, while 25% required long-term oxygen therapy. Serum Krebs von den Lungen-6, surfactant protein D, and lactate dehydrogenase levels significantly and positively correlated with the DSS.

CONCLUSIONS

Most patients registered in the NDDID have APAP/IPAP with a DSS ≥3, and about one-quarter require long-term oxygen therapy and infrequent lavages. Our results provide important details of the current prevalence and clinical practice related to APAP/IPAP with a DSS ≥3 in Japan.

Updated severity and prognosis score of pulmonary alveolar proteinosis: A multi-center cohort study in China

Background

The high-resolution computed tomography (HRCT) score is an important component of the severity and prognosis score of pulmonary alveolar proteinosis (SPSP). However, the HRCT score in SPSP only considers the extent of opacity, which is insufficient.

Methods

We retrospectively evaluated HRCT scores for 231 patients with autoimmune pulmonary alveolar proteinosis (APAP) from three centers of the China Alliance for Rare Diseases. The SPSPII was created based on the overall density and extent, incorporating the SPSP. The severity of APAP patients was assessed using disease severity scores (DSS), SPSP, and SPSPII to determine the strengths and weaknesses of the different assessment methods. We then prospectively applied the SPSPII to patients before treatment, and the curative effect was assessed after 3 months.

Results

The HRCT overall density and extent scores in our retrospective analysis were higher than the extent scores in all patients and every original extent score severity group, as well as higher related to arterial partial oxygen pressure (PaO₂) than extent scores. The mild patients accounted for 61.9% based on DSS 1-2, 20.3% based on SPSP 1-3, and 20.8% based on SPSPII 1-3. Based on SPSP or SPSPII, the number of severe patients deteriorating was higher in the mild and moderate groups. When applied prospectively, arterial PaO₂ differed between any two SPSPII severity groups. The alveolar-arterial gradient in PaO₂ (P[A-a]O₂), % predicted carbon monoxide diffusing capacity of the lung (DLCO), and HRCT score were higher in the severe group than in the mild and moderate groups. After diagnosis, mild patients received symptomatic treatment, moderate patients received pure whole lung lavage (WLL) or granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy, and severe patients received WLL and GM-CSF therapy. Importantly, the SPSPII in mild and severe groups were lower than baseline after 3 months.

Conclusion

The HRCT density and extent scores of patients with APAP were better than the extent score. The SPSPII score system based on smoking status, symptoms, PaO₂, predicted DLCO, and overall HRCT score was better than DSS and SPSP for assessing the severity and efficacy and predicting the prognosis.

Trial registration

ClinicalTrial.gov, identifier: NCT04516577.

A 44-year-old stone worker with progressive dyspnea: lessons from a new twist on an old foe

Silicosis is typically an indolent lung disease caused by long-standing occupational exposure to respirable crystalline silica, classically in professions such as sandblasting and mining.  An increasingly popular industry that has earned particular interest because of its association with silicosis is customization and installation of artificial stone countertops for domestic applications. In addition to causing a spike in cases of chronic and accelerated silicosis, both quite familiar to respiratory clinicians, outbreaks of artificial stone silicosis have brought to the fore a historically rare entity known as acute silicosis, or silicoproteinosis, a more rapid presentation of the disease. Failure to suspect this uncommon condition can lead to diagnostic confusion and therefore ineffective treatment as was true initially of the patient we describe herein.  The case description is followed by a clinical, radiological, and pathological overview of acute artificial stone silicosis (or silicoproteinosis), which is an emerging pneumoconiosis with sparse coverage in the literature to date.  This case also adds to the few existing reports on the use of therapeutic whole lung lavage for silicoproteinosis.      

Allogeneic Hematopoietic Stem Cell Transplantation After Prior Lung Transplantation for Hereditary Pulmonary Alveolar Proteinosis: A Case Report

Pulmonary alveolar proteinosis (PAP) is a rare, diffuse lung disorder characterized by surfactant accumulation in the small airways due to defective clearance by alveolar macrophages, resulting in impaired gas exchange. Whole lung lavage is the current standard of care treatment for PAP. Lung transplantation is an accepted treatment option when whole lung lavage or other experimental treatment options are ineffective, or in case of extensive pulmonary fibrosis secondary to PAP. A disadvantage of lung transplantation is recurrence of PAP in the transplanted lungs, especially in hereditary PAP. The hereditary form of PAP is an ultra-rare condition caused by genetic mutations in genes encoding for the granulocyte macrophage-colony stimulating factor (GM-CSF) receptor, and intrinsically affects bone marrow derived-monocytes, which differentiate into macrophages in the lung. Consequently, these macrophages typically display disrupted GM-CSF receptor-signaling, causing defective surfactant clearance. Bone marrow/hematopoietic stem cell transplantation may potentially reverse the lung disease in hereditary PAP. In patients with hereditary PAP undergoing lung transplantation, post-lung transplant recurrence of PAP may theoretically be averted by subsequent hematopoietic stem cell transplantation, which results in a graft-versus-disease (PAP) effect, and thus could improve long-term outcome. We describe the successful long-term post-transplant outcome of a unique case of end-stage respiratory failure due to hereditary PAP-induced pulmonary fibrosis, successfully treated by bilateral lung transplantation and subsequent allogeneic hematopoietic stem cell transplantation. Our report supports treatment with serial lung and hematopoietic stem cell transplantation to improve quality of life and prolong survival, without PAP recurrence, in selected patients with end-stage hereditary PAP.

Autoimmune Pulmonary Alveolar Proteinosis

Autoimmune pulmonary alveolar proteinosis (PAP) is a rare disease characterized by myeloid cell dysfunction, abnormal pulmonary surfactant accumulation, and innate immune deficiency. It has a prevalence of 7-10 per million; occurs in individuals of all races, geographic regions, sex, and socioeconomic status; and accounts for 90% of all patients with PAP syndrome. The most common presentation is dyspnea of insidious onset with or without cough, production of scant white and frothy sputum, and diffuse radiographic infiltrates in a previously healthy adult, but it can also occur in children as young as 3 years. Digital clubbing, fever, and hemoptysis are not typical, and the latter two indicate that intercurrent infection may be present. Low prevalence and nonspecific clinical, radiological, and laboratory findings commonly lead to misdiagnosis as pneumonia and substantially delay an accurate diagnosis. The clinical course, although variable, usually includes progressive hypoxemic respiratory insufficiency and, in some patients, secondary infections, pulmonary fibrosis, respiratory failure, and death. Two decades of research have raised autoimmune PAP from obscurity to a paradigm of molecular pathogenesis-based diagnostic and therapeutic development. Pathogenesis is driven by GM-CSF (granulocyte/macrophage colony-stimulating factor) autoantibodies, which are present at high concentrations in blood and tissues and form the basis of an accurate, commercially available diagnostic blood test with sensitivity and specificity of 100%. Although whole-lung lavage remains the first-line therapy, inhaled GM-CSF is a promising pharmacotherapeutic approach demonstrated in well-controlled trials to be safe, well tolerated, and efficacious. Research has established GM-CSF as a pulmonary regulatory molecule critical to surfactant homeostasis, alveolar stability, lung function, and host defense.

Pulmonary Alveolar Proteinosis with Severe Respiratory Failure Improved by Segmental Lung Lavage with Fiberoptic Bronchoscopy under General Anesthesia

Pulmonary alveolar proteinosis (PAP) is a rare disorder in which lipoproteinaceous materials accumulate in the alveolar compartments. A 72-year-old man was diagnosed with autoimmune PAP with severe respiratory failure. We decided to perform segmental lung lavage (SLL) with fiberoptic bronchoscopy under general anesthesia. If improvement was not significant, whole-lung lavage (WLL) would be done. SLL improved the respiratory failure and computed tomography findings. This case showed improvement in not only the area where lavage was done but also the non-lavaged area. SLL with fiberoptic bronchoscopy under general anesthesia might be an appropriate treatment option for patients with severe PAP.

Sirolimus-induced secondary pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary syndrome that is characterized by the accumulation of excess surfactant in the alveolar space, leading to impaired gas exchange. Sirolimus-induced PAP is an extremely rare entity that has only been described in the literature in a small number of case reports. We present a case of a 39-year-old female with acute lymphocytic leukemia who underwent stem cell transplant, complicated by graft-versus-host-disease (GVHD) involving the skin for which she was treated with steroids, photopheresis, sirolimus, and ruxolitinib. She was admitted to the intensive care unit (ICU) for acute on chronic hypoxic respiratory failure requiring intermittent mechanical ventilation. Computed tomography (CT) of the chest showed thickened inter- and intralobular septa with ground glass opacities and consolidation with a limited geographic pattern. Bronchoalveolar lavage fluid was stained with Periodic acid-Schiff (PAS), which was positive for extracellular proteinaceous material. Autoimmune studies including antibody levels for primary autoimmune pulmonary alveolar proteinosis (PAP) were negative. The patient was diagnosed with sirolimus-induced secondary PAP, and sirolimus was discontinued. A year later, she no longer required supplemental oxygen, and repeat CT imaging showed only faint residual disease. This is the only documented case of sirolimus-induced PAP in a stem cell transplant recipient and the first case reported in which the patient developed severe hypoxic respiratory failure requiring mechanical ventilation. In the right clinical context, PAP can be diagnosed with characteristic high resolution computed tomography (HRCT) findings, serum GM-CSF antibody levels, and bronchoscopy with bronchoalveolar lavage.

Autoimmune pulmonary alveolar proteinosis successfully treated with lung lavage in an adolescent patient: a case report

Background

Pulmonary alveolar proteinosis is a rare interstitial lung disease characterized by accumulating surfactant materials in the alveoli. The autoimmune form is by far the most common in adults, while in the pediatric age group, the vast majority of cases are congenital. We report a case of an adolescent patient diagnosed with autoimmune pulmonary alveolar proteinosis, which is unusual in this age group.

Case presentation

A-15 year-old Saudi male presented to the emergency department with a history of shortness of breath and low oxygen saturation. High-resolution computed tomography of his chest showed a global crazy-paving pattern. Autoantibodies against granulocyte-macrophage colony-stimulating factor were detected in his serum. A diagnosis of the autoimmune form of pulmonary alveolar proteinosis was confirmed after excluding other possible causes. The patient improved after he underwent whole lung lavage under general anesthesia, and he was independent of oxygen therapy after 6 months of follow-up.

Conclusion

The autoimmune form of pulmonary alveolar proteinosis is rare in the pediatric age group and should be considered when no apparent cause of this disease was found. Whole lung lavage should be the first treatment modality offered in this setting with close follow-up and monitoring.

Autoimmune pulmonary alveolar proteinosis prior to myelodysplastic syndrome

We report the first case of autoimmune pulmonary alveolar proteinosis (PAP) associated with and preceding myelodysplastic syndrome. A 74-year-old female with a history of polymyalgia rheumatica presented with six months history of progressive exertional breathlessness. Examination revealed bilateral chest crackles and exertional desaturation. A diagnosis of autoimmune PAP was made based on the presence of autoantibodies to granulocyte-macrophage colony-stimulating factor and characteristic findings on chest computed tomography, bronchoalveolar lavage, and transbronchial biopsies. Bilateral whole lung lavage was performed with prompt improvement in symptoms. Fourteen months later, she presented with new breathlessness and was diagnosed with myelodysplasia on bone marrow biopsy. No recurrence of alveolar proteinosis was detected. This case highlights the importance of follow-up and screening of patients with autoimmune PAP for haematological conditions.

Secondary pulmonary alveolar proteinosis treated by lung transplant: A case report

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a pulmonary disease characterized by disruption of surfactant homeostasis resulting in its accumulation in the alveoli. PAP is classically classified into three categories (Table 1): 1/primary (or autoimmune) with antibodies targeting the GM-CSF pathway, 2/secondary to another disease, typically a hematologic malignancy, and 3/genetic.

CASE-REPORT

A 30 year-old woman received an allogenic hematopoietic stem cell transplantation (HSCT) after treatment for acute myeloid leukemia (AML). Within the first 6 months post HSCT, she developed an ocular, oral, digestive and hepatic graft-versus-host disease associated with a mixed ventilatory defect with a very severe obstructive syndrome and a severe CO diffusion impairment. High resolution computed tomography showed a classical "crazy paving" pattern. Aspect and differential cell count of BAL were normal. All microbiological samples remained culture negative. Histo-pathological analysis of transbronchial biopsies was unremarkable. Because of the severity of the respiratory insufficiency, open-lung biopsy (OBL) could not be performed. Despite multiple immunosuppressive therapies, lung function deteriorated rapidly; the patient also developed an excavated fungal lesion unresponsive to treatment. She underwent a bilateral lung transplant 48 months after HSCT. Histo-pathological analysis of explanted lungs showed obliterative bronchiolitis (OB), diffuse PAP and invasive cavitary pulmonary aspergillosis.

CONCLUSIONS

This case illustrates the simultaneous occurrence of OB, PAP and a fungal infection in a 30-year old female patient who underwent HSCT for acute myeloid leukemia (AML). To our knowledge this is the only documented case of PAP associated with OB treated by lung transplantation.

A Case of Autoimmune Pulmonary Alveolar Proteinosis with Pulmonary Fibrosis and Asbestosis-Like Features

A 78-year-old man who had worked in the building industry visited our hospital because of groundglass opacity with smoothly thickened, intralobular interstitial lines and interlobular septal lines on chest high-resolution computed tomography (HRCT). HRCT image also showed a focal area of reticulation and pleural thickening. Lung specimens obtained by surgical lung biopsy showed accumulations of intra-alveolar periodic acid-Schiffpositive materials, usual interstitial pneumonia (UIP)-like subpleural lung fibrosis and asbestos bodies (1 body/cm2 in high-power field, ×400). Serum granulocyte-macrophage colony stimulating factor autoantibody was positive. The patient was diagnosed as having autoimmune pulmonary alveolar proteinosis (PAP) and needed differential diagnosis from secondary PAP caused from pulmonary asbestosis and UIP. Careful observation of the manifestations of pulmonary asbestosis and the progression of fibrosis using HRCT will be necessary in this patient.

Pulmonary alveolar proteinosis with upper-lobe predominance in a non-smoking female

In this report, we describe an unusual manifestation of pulmonary alveolar proteinosis (PAP). The patient is a 43-year-old non-smoking female without underlying hematologic or auto-immune disorder. Her initial presentation included non-specific respiratory symptoms (exertional dyspnoea and cough), an unremarkable physical examination, a mild elevation in her serum level of lactate dehydrogenase, a mild impairment in the diffusion capacity for carbon monoxide but a normal spirometry, and multiple ground-glass opacities with a "crazy-paving" pattern predominantly in upper lung zones on her chest radiographic images. PAP was diagnosed histologically. PAP commonly occurs in males with smoking history, and tends to affect the lung parenchyma diffusely or, as in auto-immune PAP, lower lobes predominantly. Upper-lobe predominant PAP, particularly in a non-smoking female, is rare. This report would add PAP to the list of differential diagnosis for upper-lung ground-glass opacities. A review on the relevant literature is also included in the discussion.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a syndrome characterized by the accumulation of alveolar surfactant and dysfunction of alveolar macrophages. PAP results in progressive dyspnoea of insidious onset, hypoxaemic respiratory failure, secondary infections and pulmonary fibrosis. PAP can be classified into different types on the basis of the pathogenetic mechanism: primary PAP is characterized by the disruption of granulocyte-macrophage colony-stimulating factor (GM-CSF) signalling and can be autoimmune (caused by elevated levels of GM-CSF autoantibodies) or hereditary (due to mutations in CSF2RA or CSF2RB, encoding GM-CSF receptor subunits); secondary PAP results from various underlying conditions; and congenital PAP is caused by mutations in genes involved in surfactant production. In most patients, pathogenesis is driven by reduced GM-CSF-dependent cholesterol clearance in alveolar macrophages, which impairs alveolar surfactant clearance. PAP has a prevalence of at least 7 cases per million individuals in large population studies and affects men, women and children of all ages, ethnicities and geographical locations irrespective of socioeconomic status, although it is more-prevalent in smokers. Autoimmune PAP accounts for >90% of all cases. Management aims at improving symptoms and quality of life; whole-lung lavage effectively removes excessive surfactant. Novel pathogenesis-based therapies are in development, targeting GM-CSF signalling, immune modulation and cholesterol homeostasis.

Pulmonary alveolar proteinosis developing during steroid treatment in a patient with organizing pneumonia in association with atypical chronic myeloid leukemia

Organizing pneumonia (OP) and pulmonary alveolar proteinosis (PAP) are rare complications in patients with hematologic disorders. We herein report a case of PAP that developed during steroid treatment for OP in a patient with atypical chronic myeloid leukemia. Physicians should pay close attention to these complications in patients with hematologic malignancies.

The place of high-resolution computed tomography imaging in the investigation of interstitial lung disease

INTRODUCTION

High-resolution computed tomography (HRCT) has revolutionized the diagnosis, prognosis and in some cases the prediction of therapeutic response in interstitial lung disease (ILD). HRCT represents an essential second step to a patient's clinical history, before considering any other investigation, including lung biopsy. Areas covered: This review describes the current place of HRCT in the diagnosis, prognosis and monitoring of ILD. It also lists some perspectives for the near future. Expert commentary: Since the 1980s, HRCT and its interpretation have improved, the diagnosis value of patterns, and the integration of bio-clinical elements to HRCT have been better standardized. The interobserver agreement has been investigated, allowing a better use of some limits in the interpretation of various signs. It not only takes into account one particular predominant sign, but the combination of patterns and the distribution of findings. Thanks to HRCT, the range of diagnoses and their probability are more accurately identified. The contribution of HRCT has been optimized during the multidisciplinary discussion that a difficult diagnosis calls for. HRCT quantification of the extent of diffuse lung disease becomes possible and is linked to prognosis. In the future, artificial intelligence may significantly modify the practice of radiology.

Elevated Serum Anti-GM-CSF Antibodies before the Onset of Autoimmune Pulmonary Alveolar Proteinosis in a Patient with Sarcoidosis and Systemic Sclerosis

Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of periodic acid-schiff stain-positive lipoproteinaceous materials in the alveolar space due to impaired surfactant clearance by alveolar macrophage. Autoimmune PAP is the most common form of PAP, but rarely accompanies collagen disease or sarcoidosis. We report here a rare case of autoimmune PAP preceded by systemic sclerosis and sarcoidosis. A 64-year-old woman was admitted to our hospital for blurred vision, muscle weakness of extremities, Raynaud's phenomenon, and exertional dyspnea. We diagnosed her as having systemic sclerosis complicated with sarcoidosis. Chest computed tomography (CT) and transbronchial lung biopsy showed the findings of pulmonary fibrosis without PAP. We treated her with corticosteroid and intravenous cyclophosphamide therapy, followed by tacrolimus therapy. Thereafter, her symptoms improved except for exertional dyspnea, and she began to complain of productive cough thirteen months after corticosteroid and immunosuppressant therapy. On the second admission, a chest CT scan detected the emergence of crazy-paving pattern in bilateral upper lobes. Bronchoalveolar lavage (BAL) fluid with milky appearance and a lung biopsy specimen revealed acellular periodic acid-schiff stain-positive bodies. The serum titer of anti-granulocyte macrophage colony stimulating factor (GM-CSF) antibodies was elevated on first admission and remained high on second admission. We thus diagnosed her as having autoimmune PAP. Reducing the dose of immunosuppressive agents and repeating the segmental BAL resulted in the improvement of her symptoms and radiological findings. Immunosuppressant therapy may trigger the onset of autoimmune PAP in a subset of patients with systemic sclerosis and/or sarcoidosis.

Secondary pulmonary alveolar proteinosis predominant in the transplanted lung in patients with idiopathic interstitial pneumonia: an autopsy case

A man in his 40 s with idiopathic interstitial pneumonia underwent cadaveric left single-lung transplantation from a brain-dead donor in October 2014. In October 2015, chest high-resolution computed tomography revealed centrilobular ground-glass opacities (GGOs) predominantly in the transplanted left lung, and subsequently, the shadows progressed to a geographic GGO without crazy paving. Bronchoalveolar lavage fluid analysis revealed an opaque and milky appearance, and cytopathology demonstrated foamy alveolar macrophages and abundant granular, acellular, eosinophilic, and amorphous material in the background. There was no evidence of infection. Serum anti-granulocyte-macrophage colony-stimulating factor antibody testing was negative. We diagnosed the patient with secondary pulmonary alveolar proteinosis (PAP) following lung transplantation. Autopsy revealed PAP findings predominant in the transplanted left lung, which also had dilated lymphatic vessels. In addition to defects in alveolar macrophage function from immunosuppressive therapy, impaired lymphatic drainage due to transplantation would contribute to the onset of secondary PAP in the transplanted lung.

Pulmonary alveolar proteinosis in adults: pathophysiology and clinical approach

Pulmonary alveolar proteinosis (PAP) is a diffuse lung disease that results from the accumulation of lipoproteinaceous material in the alveoli and alveolar macrophages due to abnormal surfactant homoeostasis. Identification of the granulocyte-macrophage colony-stimulating factor (GM-CSF) as an indispensable mediator of macrophage maturation and surfactant catabolism was the key discovery leading to the current understanding of the pathogenesis of most forms of PAP. Impaired GM-CSF bioavailability due to anti-GM-CSF autoimmunity is the cause of approximately 90% of adult PAP cases. Abnormal macrophage function due to endogenous or exogenous triggers, GM-CSF receptor defects, and other genetic abnormalities of surfactant production account for the remainder of causes. The usual physiological consequence of PAP is impairment of gas exchange, which can lead to dyspnoea, hypoxaemia, or even respiratory failure and death. Pulmonary fibrosis occurs occasionally in patients with PAP. For patients with moderate to severe disease, whole lung lavage is still the first-line treatment of choice. Supplemental GM-CSF is also useful, but details about indications, choice of agent, and dosing remain unclear. Other therapies, including rituximab, plasmapheresis, and lung transplantation have been described but should be reserved for refractory cases.

Secondary pulmonary alveolar proteinosis: a single-center retrospective study (a case series and literature review)

Background

Secondary pulmonary alveolar proteinosis (sPAP) is an extremely rare disease. The clinical features of sPAP patients remain to be summarizeds.

Methods

Patients pathologically diagnosed with PAP and with negative results for anti-granulocyte macrophage colony stimulating factor (GM-CSF) autoantibodies from Peking Union Medical College Hospital between January 2000 and July 2016 were retrospectively studied. The PubMed database was also searched for literature to collect published cases.

Results

In our center, nine patients were diagnosed as sPAP with a median age of 37 years. Hematological disorders, including myelodysplastic syndrome (MDS), chronic myelogenous leukemia (CML), and pulmonary tuberculosis (TB) infection were the underlying diseases. Cases secondary to MDS had very poor prognosis as all of them survived less than 2 years after their diagnosis, while those secondary to TB had favorable prognosis. Only 33.3% of cases showed interlobular septal thickening in our sPAP group. Through literature review, 164 sPAP cases were collected. The age at diagnosis was 45.0 ± 14.8 years old and the gender radio was 1.20:1 (M:F). 61.9% of cases were diagnosed by bronchoscopy. MDS and CML were common underlying diseases in 34.1% and 15.2% of patients, respectively. Patients with sPAP secondary to hematological diseases had a short survival time and half of them died within 14.95 months after diagnosis.

Conclusions

MDS and TB infection were the most frequent underlying causes of sPAP in this single-center research in China, with cases secondary to MDS having a poor survival rate. sPAP was more likely to be secondary to hematological disorders, especially MDS and CML and had a fairly poor prognosis in published cases. sPAP should be suspected in PAP patients whose CT scan presents only ground-glass opacities without interlobular septal thickening.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0590-z) contains supplementary material, which is available to authorized users.

Pulmonary Alveolar Proteinosis in Setting of Inhaled Toxin Exposure and Chronic Substance Abuse

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder in which defects in alveolar macrophage maturation or function lead to the accumulation of proteinaceous surfactant in alveolar space, resulting in impaired gas exchange and hypoxemia. PAP is categorized into three types: hereditary, autoimmune, and secondary. We report a case of secondary PAP in a 47-year-old man, whose risk factors include occupational exposure to inhaled toxins, especially aluminum dust, the use of anabolic steroids, and alcohol abuse, which in mice leads to alveolar macrophage dysfunction through a zinc-dependent mechanism that inhibits granulocyte macrophage-colony stimulating factor (GM-CSF) receptor signalling. Although the rarity and vague clinical presentation of PAP can pose diagnostic challenges, clinician awareness of PAP risk factors may facilitate the diagnostic process and lead to more prompt treatment.

Clinical features of secondary pulmonary alveolar proteinosis associated with myelodysplastic syndrome: Two case reports

RATIONALE

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder characterized by the abnormal accumulation of alveolar surfactant protein in alveolar spaces. Secondary PAP can result from myelodysplastic syndrome (MDS).

PATIENT CONCERNS

But most reports described a single case; here we reported 2 cases of PAP secondary to MDS. One case developed secondary PAP at the same time as MDS, and the other developed during the course of MDS.

DIAGNOSES

The diagnosis of PAP was made by bronchoalveolar lavage and based on the identification of periodic acid-Schiff-positive proteinaceous material. Chest high resolution CT (HRCT) scans showed variable distribution of ground glass opacities, but crazy-paving appearance was not seen in our 2 cases.

INTERVENTIONS

Because the patients' general conditions were poor, whole lung lavage was not used in the 2 cases.

OUTCOMES

And the 2 cases' prognoses were poor.

LESSONS

In conclusion, pulmonary physicians should suspect the possibility of secondary PAP when they encounter unexplained pulmonary infiltrates with some hematologic or infectious disease that shows diffuse bilateral GGO on an HRCT scan.

GM-CSF Autoantibody-positive Pulmonary Alveolar Proteinosis with Simultaneous Myeloproliferative Neoplasm

Pulmonary alveolar proteinosis (PAP) is classified as autoimmune, secondary, or genetic. We herein describe a 69-year-old man with autoimmune PAP, simultaneously diagnosed with myeloproliferative neoplasm (MPN). Two years after the diagnosis, the MPN progressed to acute myeloid leukemia, and the patient died from an alveolar hemorrhage during remission induction chemotherapy. Throughout the clinical course, no progression of PAP was observed, despite the progression to leukemia. There are few reports of autoimmune PAP with hematological malignancy, and this case demonstrated that an evaluation for GM-CSF autoantibodies is important for distinguishing the autoimmune and secondary forms of PAP, even if the patient has hematological malignancy.

Pulmonary alveolar proteinosis: Experience from a tertiary care center and systematic review of Indian literature

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a rare disorder characterized by deposition of lipoproteinaceous material within alveoli, with a variable clinical course. Here, we report an experience of management of PAP at our center. A systematic review of previously reported cases from India is also included in the article.

MATERIALS AND METHODS

This study included patients with primary PAP managed at our center from 2009 to 2015. Diagnosis of primary PAP was based on histopathologic diagnosis on bronchoalveolar lavage or transbronchial lung biopsy and absence of causes of secondary PAP. For systematic review of Indian publications, the literature search was performed using PubMed and EMBASE databases using the terms "pulmonary alveolar proteinosis'" or "alveolar proteinosis" and "India" or "Indian."

RESULTS

During the above-specified period, five patients with diagnosis of PAP were admitted at our center. Median age of patients was 32 years (interquartile range [IQR] 30.5-59); 80% were female. Mean duration (± standard deviation) of symptoms was 6.2 (±1.79) months. Anti-granulocyte-macrophage colony stimulating factor (GM-CSF) antibodies were elevated in 4 out of 5 patients (80%). For management, whole lung lavage (WLL) was done for four patients with median volume of 32.5 (IQR 18-74) L per patient. All the patients showed significant symptomatic as well as improvement in physiological parameters. Subcutaneous GM-CSF and ambroxol were given to 3 patients and 1 patient, respectively. The median follow-up of all patients was 18 (IQR 5-44) months. A systematic review of all Indian studies of PAP revealed thirty publications.

CONCLUSIONS

WLL is the most common, effective, and safe therapy in patients with PAP. GM-CSF administration is an efficacious treatment for patients with incomplete response after WLL.

Pulmonary melanoma and "crazy paving" patterns in chest images: a case report and literature review

Background

In the lung, melanoma is mostly arranged as patterns of multiple nodules, solitary nodules, or miliary invasions. Very rarely, it also displays a “crazy paving” pattern (also described as a “paving stone,” “flagstone,” or “slabstone” pattern), which is rarer still in discrete bilateral nodules. This pattern is considered to be caused by pulmonary alveolar proteinosis, but its association with various diseases is unclear.

Case presentation

A 60-year-old man was diagnosed with pulmonary melanoma. Computed tomography revealed discrete bilateral nodules surrounded by a “paving” pattern. A literature review found more than 40 types of diseases that have presented with “paving” patterns in the lung—predominantly pulmonary alveolar proteinosis, viral pneumonia, exogenous lipoid pneumonia, bacterial pneumonia, pulmonary alveolar microlithiasis, interstitial pneumonia, ARDS, squalene aspiration pneumonia, radiation pneumonitis, drug-induced pneumonitis, pulmonary leptospirosis, pulmonary hemorrhage, and pulmonary nocardiosis.

Conclusions

We describe the first case of pulmonary melanoma in the form of discrete bilateral nodules accompanied with a computed tomography paving pattern. Although pulmonary paving patterns are rare, more than 40 diseases reportedly display them; clinicians should consider melanoma of the lung in differential diagnoses for patients who show such a pattern.

A standardized blood test for the routine clinical diagnosis of impaired GM-CSF signaling using flow cytometry

Impaired signaling by granulocyte/macrophage-colony stimulating factor (GM-CSF) drives the pathogenesis of two diseases (autoimmune and hereditary pulmonary alveolar proteinosis (PAP)) representing over ninety percent of patients who develop PAP syndrome but not a broad spectrum of diseases that cause PAP by other mechanisms. We previously exploited the ability of GM-CSF to rapidly increase cell-surface CD11b levels on neutrophils (CD11bSurface) to establish the CD11b stimulation index (CD11b-SI), a test enabling the clinical research diagnosis of impaired GM-CSF signaling based on measuring CD11bSurface by flow cytometry using fresh, heparinized blood. (CD11b-SI is defined as GM-CSF-stimulated- CD11bSurface minus unstimulated CD11bSurface divided by un-stimulated CD11bSurface multiplied by 100.) Notwithstanding important and unique diagnostic utility, the test is sensitive to experimental conditions that can affect test performance. The present study was undertaken to optimize and standardize CD11b-SI test for detecting impaired GM-CSF signaling in heparinized human blood specimens from PAP patients. Results demonstrated the test was sensitive to choice of anticoagulant, pretesting incubation on ice, a delay between phlebotomy and test performance of more than one hour, and the concentration GM-CSF used to stimulate blood. The standardized CD11b-SI test reliably distinguished blood specimens from autoimmune PAP patients with impaired GM-CSF signaling from those of health people with normal signaling. Intra-subject differences were smaller than inter-subject differences in repeated measures. Receiver operating characteristic curve analysis identified a CD11b-SI test result of 112 as the optimal cut off threshold for diagnosis of impaired GM-CSF signaling in autoimmune PAP for which the sensitivity and specificity were both 100%. These results support the use of this standardized CD11b-SI for routine clinical identification of impaired GM-CSF signaling in patients with autoimmune PAP. The CD11b-SI may also have utility in clinical trials of novel therapeutic strategies targeting reduction in GM-CSF bioactivity now under evaluation for multiple common autoimmune and inflammatory disorders.

Secondary pulmonary alveolar proteinosis in hematologic malignancies

Pulmonary alveolar proteinosis (PAP), characterized by deposition of intra-alveolar PAS positive protein and lipid rich material, is a rare cause of progressive respiratory failure first described by Rosen et al. in 1958. The intra-alveolar lipoproteinaceous material was subsequently proven to have been derived from pulmonary surfactant in 1980 by Singh et al. Levinson et al. also reported in 1958 the case of 19-year-old female with panmyelosis afflicted with a diffuse pulmonary disease characterized by filling of the alveoli with amorphous material described as "intra-alveolar coagulum". This is probably the first reported case of PAP in relation to hematologic malignancy. Much progress has been made on PAP first described by Rosen which is currently classified as idiopathic or primary or autoimmune PAP. Idiopathic PAP occurs as a result of auto-antibodies directed against granulocyte-macrophage colony stimulating factor (GM-CSF) impeding the surfactant clearing function of alveolar macrophages leading to progressive respiratory failure. Whole lung lavage and GM-CSF therapy has improved outcomes in patients with idiopathic PAP. Despite major advancement in the management of hematologic malignancy and its complications, little is known about the type of PAP first described by Levinson and now known as secondary PAP; a term also used when PAP occurs due to other causes such as occupational dusts. In this article we review and analyze the limited literature available in secondary PAP due to hematologic malignancies and present a case of PAP associated with chronic lymphocytic leukemia successfully treated with bendamustine and rituximab.

A case of autoimmune pulmonary alveolar proteinosis appearing as a localized ground-glass opacity

Pulmonary alveolar proteinosis (PAP) is a rare diffuse lung disease caused by abnormal intra-alveolar surfactant accumulation; it commonly appears as a "crazy-paving" pattern on high-resolution computed tomography. Here, we report a rare case of autoimmune PAP appearing as localized ground-glass opacity. An 82-year-old woman underwent chest computed tomography (CT) at another facility for cough, and a 2-cm localized ground-glass opacity was detected at the bottom of the right upper lung lobe. When she presented for follow-up at our hospital 6 months later, she was asymptomatic. The CT examinations performed at that point and 2 months thereafter did not reveal any changes. However, a CT examination performed after 5 months revealed slight increases in size and concentration. Adenocarcinoma in situ or minimally invasive adenocarcinoma was suspected. Incomplete lobulation between the upper and middle lobes of the right lung was detected, and video-assisted thoracoscopic lobectomy of the upper lobe and partial resection of the middle lobe of the right lung were performed. Histological examination revealed alveoli and terminal bronchioles filled with eosinophilic proteinaceous material positive for periodic acid-Schiff stain. The histopathological diagnosis was PAP and positive serum anti-GM-CSF antibody findings confirmed autoimmune PAP.

Primary pulmonary alveolar proteinosis: computed tomography features at diagnosis

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is characterized by an abnormal accumulation of periodic acid-schiff-positive lipoproteinaceous material in the alveoli. Early diagnosis allows setting up of therapeutic lung lavages, which reduces the need for oxygen supplementation and weight gain.

OBJECTIVE

To provide a description of radiological features by CT at the onset of primary PAP in children.

MATERIALS AND METHODS

The clinical and radiological data of 24 patients, including 16 boys and 8 girls (median age: 12 months), diagnosed with a primary form of PAP between April 1992 and May 2012 in a tertiary referral hospital, were retrospectively reviewed. CT images were examined for the presence of alveolar and interstitial elementary lesions. Correlation between clinical and radiological findings was assessed.

RESULTS

The types of elementary lesions detected were: ground-glass opacities (n = 24), intralobular lines (n = 24), thickened interlobular septa (n = 22), thickened fissures (n = 21), airspace consolidation (n = 16), hyperinflation (n = 16), cystic lesions (n = 2) and micronodules (n = 1). A crazy-paving pattern was found in 92% of cases. Consolidation and hyperinflation were especially detected in younger children (median age, 8 months, P < 0.01). A density dependent gradient was found. The distribution of the lesions was symmetrical. There was no correlation between radiological and clinical data of severity of the disease.

CONCLUSION

CT findings are suggestive of diagnosis of PAP in immunocompetent children with chronic respiratory failure.

Autoimmune pulmonary proteinosis in a Chilean teenager, a rare aetiology of interstitial lung disease

Interstitial lung disease (ILD) is rare and encompasses a heterogeneous group of diseases, and is even rarer in children than in adults. ILDs compromise more than 100 different entities, including pulmonary alveolar proteinosis (PAP). There are many causes of PAP in children, including surfactant protein gene mutations (SFTPB, SFTPC, ABCA3, TTF-1), GMCSF receptor mutations and antigranulocyte-macrophage colony-stimulating factor autoantibodies. We report a case of a 13-year-old Chilean girl who presented with an 8-month history of progressive exercise intolerance, fatigability and diminished school performance. Physical examination revealed resting tachypnoea, a few basal bilateral inspiratory crackles, and hypoxaemia on minimal exertion. Clinical suspicion and evaluation, including international collaboration, led to the diagnosis of autoimmune PAP and specific therapy for the condition.

Features of idiopathic pulmonary alveolar proteinosis in high resolution computed tomography

Background

Although the crazy-paving pattern on computed tomography is characteristic for pulmonary alveolar proteinosis (PAP), it is not specific and has not been compared between idiopathic and secondary PAPs in the large studies. The aim of this study was to determine the high resolution computed tomography (HRCT) features of idiopathic PAP.

Material/Methods

HRCT images of 35 patients (mean age: 38±14years; 54.3% male) with idiopathic PAP (proved by bronchoalveolar lavage or biopsy) were reviewed by two experienced pulmonary radiologist and detailed findings were reported.

Results

The predominant HRCT presentation of PAP was interlobular septal thickening (ILST;100%) and ground glass opacities (GGOs; 91.7%), resulting in crazy-paving pattern (83%). All patients had diffuse bilateral lung involvement that was symmetric in 97%. ILST and GGO without crazy-paving were seen in 17% and 14.7%, respectively. The overall extent of parenchymal involvement was 50 to 75% in 80% of patients. Thirty three cases (94%) had areas of geographic sparing within the affected lung. Peripheral sparing was seen in 85.7% of patients, including three patterns with some overlap: costophrenic angle (80%), apices (60%), and subpleural (57%) sparing. Other HRCT findings were: consolidation (63%), pulmonary nodules (31.4%), mediastinal and/or hilar lymphadenopathy (23%), mass-like consolidation (17%), pleural effusion (8.6%), and honey combing (5.7%). All female patients (n=16) had crazy-paving, while 13 out of 19 (68%) male patients had crazy-paving on their lung HRCT (p=0.02).

Conclusions

This study demonstrated that the predominant HRCT presentation of idiopathic PAP was interlobular septal thickening and ground glass opacities, resulting in crazy-paving pattern.

A case of secondary pulmonary alveolar proteinosis, but prior to myelodysplastic syndrome

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder. We herein report the first case of PAP that happened 2 years before myelodysplatic syndrome (MDS). A 34-year-old Chinese presented with a developed recurrent cough and shortness of breath. Computed tomography scan disclosed ground-glass opacities with interlobular septal thickening. Histological examination showed eosinophilic dense homogenous material filling in the alveolar. This precipitate had a fine granular appearance. The eosinophilic material was periodic acid-Schiff reaction-positive. The patient was diagnosed with PAP. Two years later he was admitted to a hospital because of dizziness of 1-month duration. Hematological examination showed white blood cells was 2700, hemoglobin was 7.4 g/dL, and platelet count was 21,000 platelets/mm(3). Following bone marrow biopsy and histopathologic examination, he was diagnosed with MDS with refractory anemia and excess blasts. So for PAP patients, follow-up tests should be considered in order to find any possible underlying disease.

Clinical features of three cases with pulmonary alveolar proteinosis secondary to myelodysplastic syndrome developed during the course of Behçet's disease

We have previously reported that myelodysplastic syndrome (MDS) is the most common underlying disease in cases of secondary pulmonary alveolar proteinosis (PAP). Here, we present 3 MDS cases in which PAP developed during the course of Behçet's disease (BD). All patients carried trisomy 8 in the bone marrow. Chest HRCT scans showed variable distribution of ground glass opacities, but none of the scans showed so called "crazy paving appearance". Two patients with intestinal BD who underwent potent immunosuppressive therapy died of sepsis. These findings demonstrate that PAP secondary to MDS may be occasionally associated with BD.

Unsuspected pulmonary alveolar proteinosis in a patient with a slow resolving pneumonia: A case report

Pulmonary Alveolar Proteinosis (PAP) is a rare condition with an incidence of one in two million and is classified as primary or secondary. This is the first reported case presenting as a slow resolving pneumonia.