Alveolar microlithiasis: A rare cause of breathlessness since childhood

Ram Awadh Singh Kushwaha; Rajiv Garg; Santosh Kumar; Sanjeev Kumar Verma; Ashwini Kumar Mishra; Neha Kapoor

doi:10.4103/0975-9727.160702

CASE REPORT

Year : 2015 | Volume : 6 | Issue : 2 | Page : 166-168

Alveolar microlithiasis: A rare cause of breathlessness since childhood

Ram Awadh Singh Kushwaha, Rajiv Garg, Santosh Kumar, Sanjeev Kumar Verma, Ashwini Kumar Mishra, Neha Kapoor
Department of Pulmonary Medicine, King George Medical University, Lucknow, Uttar Pradesh, India

Date of Web Publication

13-Jul-2015

Correspondence Address:
Dr. Ram Awadh Singh Kushwaha
Department of Pulmonary Medicine, King George Medical University, Lucknow, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/0975-9727.160702

Abstract

Pulmonary alveolar microlithiasis (PAM) is an uncommon chronic disease characterized by calcifications within the alveoli and a paucity of symptoms in contrast to the imaging findings. It occurs sporadically and it is regarded as an autossomal recessive lung disease. The pathogenesis of PAM has yet to be elucidated. The disorder has a protracted course and there is no treatment available. We report a case of 21 years-old male who presented to us with complaint of exertional breathlessness since childhood. Diagnosis of pulmonary alveolar microlithiasis was made on the basis of clinical features and laboratory findings.

Keywords: Breathlessness, diffuse nodular shadows, pulmonary alveolar microlithiasis (PAM)

How to cite this article:
Kushwaha RA, Garg R, Kumar S, Verma SK, Mishra AK, Kapoor N. Alveolar microlithiasis: A rare cause of breathlessness since childhood. Muller J Med Sci Res 2015;6:166-8

How to cite this URL:
Kushwaha RA, Garg R, Kumar S, Verma SK, Mishra AK, Kapoor N. Alveolar microlithiasis: A rare cause of breathlessness since childhood. Muller J Med Sci Res [serial online] 2015 [cited 2023 Mar 26];6:166-8. Available from: https://www.mjmsr.net/text.asp?2015/6/2/166/160702

Introduction

Pulmonary alveolar microlithiasis (PAM) is an uncommon chronic disease characterized by calcifications within the alveoli and a paucity of symptoms in contrast to the imaging findings. It occurs sporadically and it is regarded as an autossomal recessive lung disease. The pathogenesis of PAM has yet to be elucidated. The diagnosis is made usually on an incidental radiographic film in symptomless patients. There is a striking contrast between the paucity of signs and symptoms and the marked radiographic features. PAM is thought to be an autosomal recessive disease with <600 patients reported worldwide.

Case Report

A 21 years old male, Non Smoker, Student R/O Sitapur presented to us with chief complaints of breathlessness since childhood. Breathlessness was non progressive in nature, occured only during exertion and was having no diurnal, postural or seasonal variation. It relieved on taking rest. There was no history of cough, chest pain, fever, hemoptysis, pedal edema. There was also no significant history of similar illness in the family. The respiratory and systemic examinations were totally within normal limits. All the routine blood investigations were also in the normal range. Chest X Ray PA view was done to search for the possible cause of breathlessness which was suggestive of bilateral diffuse nodular shadows more on lower lung field (sand storm lung) [Figure 1]. Spirometry was done which revealed increased FEV1/FVC with decreased FVC suggestive of restrictive defect.CT Scan Thorax was done to further evaluate the nodular shadows which showed bilateral multiple fine nodular lesions with basal predominance. Intra and interlobular septal thickening present in both lung fields. Foci of calcification noted in both lung fields, pericardium and mediastinal pleura. Black pleura sign was also present (due to small subpleural cyst) [Figure 2] and [Figure 3].

Figure 1: X-Ray chest showing bilateral diffuse nodular shadows more on lower zone (sand storm lung)

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Figure 2: CT scan thorax showing foci of calcification in pericardium and mediastinal pleura

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Figure 3: CT scan thorax showing bilateral multiple fine nodular lesions with basal predominance. Intra and interlobular septal thickening present in both lung fields. Black pleura sign also present (due to small subpleural cyst)

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There was clinico radiological dissociation as the patient was quite asymptomatic despite of a lot of radiological findings. A provisional diagnosis of pulmonary alveolar microlithiasis (PAM) was made. To support our diagnosis HRUSG scrotum was done which was suggestive of left testicular calcification (testicular microlithiasis) [Figure 4]. This led us to confirm our diagnosis as PAM.

Figure 4: USG scrotum showing calcification of left testis

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Discussion

Pulmonary alveolar microlithiasis (PAM) is a rare disease of unknown etiology characterized by the widespread intra-alveolar deposition of laminated calcispherites in the lung. ^[1] Although the aetiology of PAM remains unclear, mutations of the SLC34A2 gene, which encodes a type IIb sodium-dependent phosphate co-transporter (NaP _i -IIb), are considered to be the cause of the disease. ^[2] As a result of this mutation, the protein is unable to transport phosphorus ions from the alveolar space into type II pneumocytes, and this failure leads to the development of calcospherites in the alveolar space. ^[3] Most patients remain symptom-free for many years despite extensive radiological changes. ^[4],[5],[6] This condition was first described in 1856 by Friederich ^[7] as "Corpora-Amylacea in den lungen». Puhr in 1933 ^[8] used the term as Micralithasis alveolaris pulmonum. PAM is thought to be an autosomal recessive disease with <600 patients reported worldwide. ^[9] Most patients are between the ages 30 to 50 years at the time of diagnosis. Precise assessment of the history of alveolar microlithiasis is difficult. Therefore, in many cases, the diagnosis is made as an incidental radiographic film in symptomless patients. ^[10] There is a striking contrast between the paucity of signs and symptoms and the marked radiographic features. Patients eventually develop dyspnoea on exertion that limits their physical activity. Physical signs are conspicuous by their absence for most of its long course, though crackles, clubbing, cyanosis and signs of respiratory failure may be observed ultimately. Eventually respiratory failure and cor pulmonale supervene. Survival of 10-20 years is characteristic. Features on X ray Chest includes sand like calcified nodules (Sand Storm Lung). Pulmonary functions have been studied in a few patients with this disorder, and are usually normal or only slightly impaired for a long period following diagnosis. A restrictive ventilator defect (also seen in our patients) and diminished diffusing capacity are the most frequently reported abnormalities. This is largely related to alveolar filling. Bone scan or transbronchial lung biopsy are useful in confirming the diagnosis. ^[11],[12] CT scan of the chest reveals a diffuse infiltrative pattern. Findings of micronodular calcifications, Black pleura sign, interstitial abnormalities are typical. These interstitial changes correlate with pulmonary functions. 99mTc diphosphonate scan reveals increased uptake of the isotope throughout both lungs. ^[13] The disorder is slowly progressive and there is no definite therapy ^[14] So far no reversible treatment of this disorder is known. It has been proposed that a combined heart/lung transplant might be the possible way to prolong the life of the patients. Diphosphonates have been used to inhibit the microcrystal growth formation. ^[15] Nasal CPAP has shown to improve oxygenation in some. Although specific findings in HRCT scan could lead to diagnosis of PAM, other cases of diffuse pulmonary calcification should be considered for differential diagnosis, including metastatic pulmonary calcification, amyloidosis, and dendriform pulmonary ossification. ^[16] The knowledge of typical HRCT findings of this disease can lead to establishment of the diagnosis.

Conclusion

In conclusion, PAM is a rare disease that can present with no symptoms. Characteristic HRCT findings can aid in diagnosis of this disease using less invasive procedures. Due to the inability to certify clear etiological and pathogenic factors, a therapeutic approach is difficult.

References

1.	Moran CA, Hochholzer L, Hasleton PS, Johnson FB, Koss MN. Pulmonary alveolar microlithiasis: A clinicopathologic and chemical analysis of seven cases. Arch Pathol Lab Med 1997;121:607-11.
2.	Hoshino H, Koba H, Inomata SI, Kurokawa K, Morita Y, Yoshida K, et al. Pulmonary alveolar microlithiasis: High-resolution CT and MR findings. J Comput Assist Tomogr 1998;22:245-8.
3.	Fraser RS, Pare PD. Fraser and Pare′s Diagnosis of Diseases of The Chest. Vol. 2. Philadelphia, London: W. B. Saunders Company; 1970. p. 1131-4.
4.	Mandi L, Simay A, Kelemen JT, Szabó A, Dayka A. Alveolar microlithiasis. Prax Pneumol 1968;22:230-7.
5.	Sosman MC, Dodd GD, Jones WD, Pillmore GU. The familial occurrence of pulmonary alveolar microlithiasis. Amer J Roentgenol Radium Ther Nucl Med 1957;77:947-1012.
6.	Friederich N. Zur Entwickelungsgeschichte der corpora amylacea in den Lungen. Virchows Arch Path Anat 1856;10:507. Quoted by Coetzee (1970).
7.	Corut A, Senyigit A, Ugur SA, Altin S, Ozcelik U, Calisir H, et al. Mutations in SLC34A2 cause pulmonary alveolar microlithiasis and are possibly associated with testicular microlithiasis. Am J Hum Genet 2006;79:650-6.
8.	Tachibana T, Hagiwara K, Johkoh T. Pulmonary alveolar microlithiasis: Review and management. Curr Opin Pulm Med 2009;15:486-90.
9.	Moran CA, Hochholzer L, Hasleton PS, Johnson FB, Koss MN. Pulmonary alveolar microlithiasis. A clinicopathologic and chemical analysis of seven cases. Arch Pathol Lab Med 1997;121:607-11.
10.	Tribel HJ, Von Hulset M, Schofer M. Fortgeschrittene microlithiasis pulmonum. Advanced Pulmonary Alveolar Microlithiasis. Rpntgen-blftter 1987;10:286-8.
11.	Puhr L. Microlithiasis alveolaries pulmonum. Virchows Arch Path Anat 1933;290:156-60.
12.	Jönsson ÅL, Simonsen U, Hilberg O, Bendstrup E. Pulmonary alveolar microlithiasis: Two case reports and review of the literature. Eur Respir Rev 2012;21:249-56.
13.	Kang HW, Kim TO, Oh IJ, Kim YI, Lim SC, Choi YD, et al. A case of pulmonary alveolar microlithiasis. J Korean Med Sci 2011;26:1391-3.
14.	Wallis C, Whitehead B, Malone M, Dinwiddie R. Pulmonary alveolar microlithiasis in childhood: Diagnosis by transbronchial biopsy. Pediatr Pulmonol 1996;21:62-4.
15.	Göcmen A, Toppare MF, Kiper N, Büyükpamukcu N. Treatment of pulmonary alveolar microlithiasis with a diphosphonate - preliminary results of a case. Respiration 1992;59:250-2.
16.	Chung MJ, Lee KS, Franquet T, Müller NL, Han J, Kwon OJ. Metabolic lung disease: Imaging and histopathologic findings. Eur J Radiol 2005;54:233-45.