Pulmonary alveolar microlithiasis: two case reports and review of the literature

Abstract

Pulmonary alveolar microlithiasis is a rare diffuse lung disease characterised by deposition of calcium phosphate within the alveolar airspaces. The disease is usually discovered from birth up to 40 yrs of age and is often diagnosed incidentally during radiography of the chest for other reasons. Many patients are asymptomatic and the majority of patients either have normal or restrictive pulmonary function. The clinical course of the disease varies. While it remains static in some patients, it progresses into pulmonary fibrosis, respiratory failure and cor pulmonale in others. With the exception of lung transplantation, there is no known effective treatment for the disease. Although the aetiology remains unclear, mutations of the solute carrier family 34 (sodium phosphate), member 2 gene (the SLC34A2 gene), which encodes a sodium/phosphate cotransporter, are considered to be the cause of the disease.We present two cases of pulmonary alveolar microlithiasis with different mutations in the SLC34A2 gene that have not been previously described, and a review of the literature.KEYWORDS: Alveolar microlithiasis, genetic polymorphisms, type IIb sodium-dependent phosphate co-transporter P ulmonary alveolar microlithiasis (PAM) is a rare diffuse lung disease. It was first named in 1933 by PUHR [1], and is characterised by deposition of spherical calcium phosphate concretions (microliths) in the alveoli [2][3][4]. Although the aetiology remains unclear, PAM is thought to be an autosomal recessive disease caused by mutations of the solute carrier family 34 (sodium phosphate), member 2 gene (the SLC34A2 gene), which encodes a sodium phosphate cotransporter [5].Herein, we present two cases of PAM with different mutations in the SLC34A2 gene that have not been previously described and, in addition, we review the literature. CASE ONEA 49-yr old male from Denmark was referred to the Dept of Respiratory Medicine, Aarhus University Hospital (Aarhus, Denmark) for diagnostic investigation in April 2005. The patient was adopted, and therefore the family history was unknown. He was complaining of fatigue and progressively worsening dyspnoea over the last 4 yrs. He had no cough or sputum. He was a heavy smoker (30 pack-yrs).Upon first admission, the ECG showed signs of serious ischaemia and he was transferred to the

Modeling pulmonary alveolar microlithiasis by epithelial deletion of the Npt2b sodium phosphate cotransporter reveals putative biomarkers and strategies for treatment

“…Pulmonary alveolar microlithiasis (PAM) is a rare, autosomal recessive lung disease in which calcium phosphate crystal formation in the alveolar space results in progressive radiographic opacification, pulmonary fibrosis, and respiratory failure (1–10). PAM is associated with consanguinity and is most common in Japan, Turkey, and Italy, with about 700 cases reported in the medical literature to date.…”

Lung transplantation in an intensive care patient with pulmonary alveolar microlithiasis - a case report

“…Bonette et al recommended bilateral lung transplantations instead of unilateral transplants on the grounds of resistant shunt development in a lung transplantation series of 14 cases, one of which was caused by PAM 12 . Besides, no recurrence was detected in the presented cases or series 7, 8, 10, 13, 14 . Moon et al reported the case of a patient who survived for 15 postoperative years with no recurrence after the lung transplantation was performed after PAM diagnosis 8 .…”

“…Ozçelik et al have described the positive effects of the long term use of sodium etidronate which is effective by inhibiting the hydroxyapatite microcrystal formation in pediatric patients 11 . However, there are also some studies showing that the sodium etidronate treatment is ineffective 7 .…”

“…Lung transplantation is a treatment option for PAM patients and is recommended in severe cases of oxygen dependent respiratory failure before the onset of right heart failure 7, 8, 10 . Bonette et al recommended bilateral lung transplantations instead of unilateral transplants on the grounds of resistant shunt development in a lung transplantation series of 14 cases, one of which was caused by PAM 12 .…”

“…The only known treatment is lung transplantation performed before the onset of right heart failure. No recurrence has been reported after transplantation 7, 8 . Here we present the case report of the first Turkish patient followed-up in the intensive care unit (ICU) with the diagnosis of PAM, who needed ventilator support at the time of discharge from the ICU and received lung transplantation in Austria.…”