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Year : 2003  |  Volume : 13  |  Issue : 3  |  Page : 277-279
Case report - pulmonary alveolar microlithiasis

Department of Radiology and Imaging, V.S. General Hospital, Smt. N.H.L Municipal Medical College, Ahmedabad, India

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Keywords: Pulmonary alveolar microlithiasis, HRCT Chest

How to cite this article:
Shah M S, Nanavati K I, Airon N, Shah R R, Joshi B D. Case report - pulmonary alveolar microlithiasis. Indian J Radiol Imaging 2003;13:277-9

How to cite this URL:
Shah M S, Nanavati K I, Airon N, Shah R R, Joshi B D. Case report - pulmonary alveolar microlithiasis. Indian J Radiol Imaging [serial online] 2003 [cited 2020 Nov 28];13:277-9. Available from:

   Introduction Top

Pulmonary Alveolar Microlithiasis is a rare disease characterized by the presence within alveolar spaces, of numerous calcispherytes. It was first described in 1918, with 225 cases recorded in the world literature.

We would like to present a report of Pulmonary Alveolar Microlithiasis, which was detected in two siblings.

   Case report Top

A 21 year old male came to the hospital for routine medical fitness, for which chest radiograph was taken. Chest radiograph [Figure - 1]a revealed the presence of innumerable, widespread small nodules, diffusely involving both the lungs. However, the patient was totally asymptomatic and had no respiratory complaints. The nodular opacities were sharply defined, discrete and showed greater involvement of lower zones as compared to the upper zones. HRCT & pulmonary function tests were done. HRCT of the thorax [Figure - 1] b & c showed the presence of widespread intraalveolar calcification (of density 462 HU in [Figure - 1]b representing the so-called microliths or calcospheres. Pulmonary function test reports were normal.

In view of familial association of this disease, the patient's sister, who was 25 years of age was called for chest radiograph. She was a known case of pulmonary tuberculosis, diagnosed four years back and was treated for it. Unfortunately, previous chest radiographs were not available with her. Her chest radiograph, HRCT and pulmonary function tests were done. The chest radiograph [Figure - 2]a and HRCT [Figure - 2]b revealed multiple, widespread nodular opacities of calcific density with fibrosis and cavity in left upper lobe. In addition, the chest radiograph revealed obliteration of the mediastinal & diaphragmatic contours due to multiple high density nodules. Her pulmonary function test reports were also normal.

   Discussion Top

Pulmonary Alveolar Microlithiasis is a rare disease characterized by the presence of numerous tiny calculi (calcispherytes) within the alveolar spaces. Alveolar Microlithiasis occurs worldwide, mainly one-quarter of recorded patients are from Turkey. In Japan, peak incidence occurs between the ages of four to nine years, but in Western countries the majority of reported cases have been in patients between the ages of 30 & 50 years. Sex incidence is approximately equal.

The etiology & pathogenesis of Pulmonary Alveolar Microlithiasis are unknown. Hypothetical mechanisms that have been proposed include an inborn error of metabolism, an unusual response to an unspecified pulmonary insult, an immune reaction to various irritants, and an acquired abnormality of calcium or phosphorus metabolism. Familial occurrence has been noted in more than half of the reported cases. However, the disease in this situation has been restricted almost completely to siblings, suggesting that environmental rather than genetic factors may be more important.

Pulmonary Alveolar Microlithiasis is characterized pathologically by the accumulation of numerous, largely intraalveolar calcified bodies. Microliths range from 0.01 to 3 mm in diameter. Chemical analysis and energy-dispersion x-ray microanalysis have shown them to be composed of calcium phosphate. In the early stages of the disease, the alveolar walls appear perfectly normal, later on interstitial fibrosis results in alveolar wall thickening, sometimes associated with blebs, bullae and giant cell formation.

The majority of patients are asymptomatic when Pulmonary Alveolar Microlithiasis is first diagnosed. The first symptom to develop in advanced cases is dyspnea on exertion. Cough and expectoration are uncommon, but occasionally patient produce expectoration with microliths. As the disease progresses, respiratory insufficiency may develop with cyanosis, clubbing of the fingers and clinical signs of Cor pulmonale. Pulmonary function studies vary considerably from case to case depending on both the extent of the replacement of the alveolar air by concretions and the presence or absence of interstitial fibrosis. The prognosis appears to be variable. It has been suggested that in many patients, the microliths continue to form and perhaps increase in size as the disease progresses. However, there is no doubt that the disease may become "arrested" & the deposition of microliths may cease.

Chest radiograph show very fine sand like micro nodulation diffusely involving both lungs. Regardless of the effect of superimposition or summation of shadows, individual deposits are usually identifiable particularly with magnification roentgenography. Very sharply defined, they measure less than 1 mm in diameter and are discrete.

The overall density is greater over the lower than the upper zones, probably because of increased thickness of lung rather than selectively greater involvement. The opacities may be so numerous as to appear confluent, in which circumstance, a normally exposed chest radiograph shows the lungs as almost uniformly white, often with total obliteration of the mediastinal and diaphragmatic contours. Pleural thickening has been described, although it is probable that this roentgenographic appearance is caused not by actual thickening of the pleura itself but by a visual effect produced by an exceptionally heavy concentration of microliths in the subpleural parenchyma.

HRCT Thorax shows that alveolar calcification is either micro nodular or ground glass with postero-basal predominance. The occasional 5 mm nodule presumably represents dystrophic ossification seen histopathologically. Calcification may be uniform or may show some microscopic structure with accentuation along the pleural margins and fissures adjacent to interlobular septa (giving polygonous structures) & bronchovascular bundles explaining the coarsely linear nodulations, reticulations, & septal lines occasionally seen on chest radiograph[7].

   References Top

1.Chalmers AG,Wyatt J,Robinson PJ. Computed Tomographic & Pathological findings in Pulmonary Alveolar Microlithiasis. British Journal of radiology 1986; 59: 408-411   Back to cited text no. 1  [PUBMED]  
2.Sosman MC,Dodd GD,Jones WD,et al. The Familial occurrence of Pulmonary Alveolar Microlithiasis. American Journal of Roentgenology 1957; 77: 947-1012   Back to cited text no. 2    
3.Balikian JP,Fuleihan FJD,Nucho CN. Pulmonary Alveolar Microlithiasis .Report of five cases with special reference to roentgen manifestation . American Journal of Roentgenology 1968; 103: 509-518   Back to cited text no. 3    
4.Helbich TH,Wojnarovsky C,Wunderbaldinger P et al. Pulmonary Alveolar Microlithiasis in children :Radiographic & High resolution CT findings. American Journal of Roentgenology 1997; 168 : 63-65   Back to cited text no. 4    
5.Cluzel P,Grenier P,Bernadac P,et al. Pulmonary Alveolar Microlithiasis : CT findings. Journal of Computed Assisted Tomography 1991;15: 938-942   Back to cited text no. 5    
6.Winzelberg GG, Boller M,Sachs M et al. CT evaluation of Pulmonary Alveolar Microlithiasis. Journal of Computed Assisted Tomography 1984; 8: 1029-10314.   Back to cited text no. 6    
7.Hoshino H, Koba H, Inomata S-I, et al. Pulmonary Alveolar Microlithiasis :High Resolution CT & MR findings. Journal of Computed Assisted Tomography 1998; 22 : 245-248.  Back to cited text no. 7    

Correspondence Address:
M S Shah
14, Vibhuti Society, near baliakaka Mandir, Old Dhor Bazaar, Ahmedabad
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Source of Support: None, Conflict of Interest: None

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[Figure - 1], [Figure - 2]


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