Correspondence

Pulmonary Alveolar Microlithiasis Revisited

N Engl J Med 2003; 348:84-85January 2, 2003

Article

To the Editor:

Barbolini et al. (July 4 issue)1 describe two cases of pulmonary alveolar microlithiasis in siblings, which they attribute to a genetic trait. The microliths are almost spherical and are concentrically laminated, calcified bodies with or without bone formation.

In 1956, a colleague and I described pulmonary alveolar microlithiasis in two separate cases of mitral stenosis due to rheumatic heart disease.2 The microliths were uneven, bosselated structures with lamination and massive calcification (Figure 1Figure 1Irregular Alveolar Microlith Characterized by Lamination, Calcification, and a Bosselated Structure, with Incorporated Cells (Hematoxylin and Eosin, ×400). and Figure 2Figure 2Irregular Microlith with Lamination and Massive Calcification (Hematoxylin and Eosin, ×400).), unlike those shown by Barbolini et al., which are oval and laminated and resemble corpora amylacea. The microliths we described appeared to be due to organization of chronic alveolar exudate, particularly in association with mitral stenosis.

Thus, there appear to be two types of alveolar microlithiasis. One type is characterized by round or oval microliths that may have a genetic basis, and the other by irregular, bosselated microliths that are largely due to mitral stenosis. Bone formation occurs in both types.

Raymond Yesner, M.D.
Yale University School of Medicine, New Haven, CT 06520-8023
raymond.yesner@yale.edu

2 References

1. 1

   Barbolini G, Rossi G, Bisetti A. Pulmonary alveolar microlithiasis. N Engl J Med 2002;347:69-70
   Full Text | Web of Science | Medline

2. 2

   Yesner R, Skorneck AB. Pulmonary alveolar microlithiasis in mitral stenosis. Am J Pathol 1956;32:611-611 abstract.
   Web of Science

Author/Editor Response

We appreciate the comments of Dr. Yesner, but only partly agree with him. He states that there seem to be two major forms of pulmonary alveolar microlithiasis: a form related to a familial predisposition and a sporadic form that may be associated with many other medical conditions, such as mitral stenosis, nephrolithiasis, the milk alkali syndrome, pulmonary fibrosis, infections, or the desert lung syndrome.1-4

We believe that it is simplistic to suggest that pulmonary alveolar microlithiasis can be subclassified merely on the basis of the shape of the microliths. This suggestion would require a morphologic analysis of pulmonary alveolar microlithiasis in a large series of cases before any conclusion might be drawn. More important, what remains to be seen is whether cases of pulmonary alveolar microlithiasis that are supposedly associated with genetic factors may actually be triggered by other, unsuspected conditions and whether apoptotic activity has a role only in familial cases or also in the sporadic variant.

Giuseppe Barbolini, M.D.
Giulio Rossi, M.D.
University of Modena and Reggio Emilia, I-41100 Modena, Italy
rossi.giulio@unimo.it

4 References

1. 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;121:607-611
   Web of Science | Medline

2. 2

   Badger TL, Gottlieb L, Gaensler EA. Pulmonary alveolar microlithiasis, or calcinosis of the lungs. N Engl J Med 1955;253:709-715
   Full Text | Web of Science | Medline

3. 3

   Nouh MS. Is the desert lung syndrome (nonoccupational dust pneumoconiosis) a variant of pulmonary alveolar microlithiasis? Report of 4 cases with review of the literature. Respiration 1989;55:122-126
   CrossRef | Web of Science | Medline

4. 4

   Chan ED, Morales DV, Welsh CH, McDermott MT, Schwarz MI. Calcium deposition with or without bone formation in the lung. Am J Respir Crit Care Med 2002;165:1654-1669
   CrossRef | Web of Science | Medline