High resolution computed tomographic features of pulmonary alveolar microlithiasis
Introduction
Pulmonary alveolar microlithiasis (PAM) is a rare, chronic lung disease with unknown etiology characterized by extensive intra-alveolar spherical calcium and phosphate deposition throughout both lung parenchymas.
The incidence of PAM is high in certain countries such as Turkey, Italy and USA [1], [2]. Patients with PAM usually show sand like micro nodular infiltration particularly marked at lower zones predominantly at para cardiac areas in their chest X-rays. Since there is a surprising discordance between chest X-ray findings and clinical presentation, chest X-ray is almost pathognomonic for the diagnosis of PAM [1], [2], [3]. Even though pulmonary parenchyma can be examined much more detailed with high resolution computed tomography (HRCT) than chest X-ray, HRCT findings of PAM were not fully described in the current literature. There are several studies indicating CT findings of PAM such as thickening of interlobular septa, thickening of peri bronchovascular interstitium, ground glass opacity, paraseptal emphysema etc. but most of which were based on single case or few case reports [3], [4], [5], [6], [7], [8], [9].
PAM has not a uniform clinical beginning and a uniform clinical course [2], [3]. Nonuniformity of clinical features might be related to pulmonary parenchymal alterations in patients with PAM.
Cases at early stages of the disease show a surprisingly intact lung parenchyma and the disease is initially endoalveolar and then undergoes progression with the development of parenchymal alterations [3], [10].
We hypothesized that there might be a relationship between profusion of micro nodules (MN) and pulmonary parenchymal alterations in patients with PAM.
The aim of this study was to interpret and to contribute to describe HRCT findings of PAM and to investigate a correlation between profusion of MNs and pulmonary parenchymal alterations in patients with PAM.
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Material and method
Inpatient records from 1998 to 2004 were screened to find out patients with a diagnosis of PAM in archive of Department of Pulmonary Medicine in Gulhane Military Medical Academy. Eight patients were found recorded with a diagnosis of PAM. In addition to these eight patients there were two recently diagnosed patients who were examined prospectively. A total of 10 patients with PAM were included into the study. All patients were male and their mean age was 22 ± 3.2. None of the patients had a
Method of diagnosis
Five of eight patients and two new patients were diagnosed based on histopathological, radiological and clinical findings, while three patients’ diagnosis were based on radiological and clinical findings. Fiberoptic bronchoscopy and transbronchial biopsies yielded histopathologic diagnoses in seven patients. Histopathologic findings of transbronchial lung biopsy showed concentric lamellar calcified microliths with hematoxylin–eosin stain (Fig. 1). Fiberoptic bronchoscopy had not been performed
Discussion
We have shown that patients with PAM may have all kind of features of interstitial lung disease on their HRCTs in varying degrees; in some patients ILST was the prominent feature, in the others PB and in some CLA and so on. PAM has not a uniform clinical beginning and a uniform course. Some patients may have symptoms some patients not. It has a worse prognosis in some patients resulting with death as a consequence of respiratory failure than some patients with a very long silent period of the
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