Extraskeletal
osteomas have not been described in the lung.
Tumors with osseous elements can be found, such as
hamartoma and
amyloid tumor, and reactive lesions such as osseous
metaplasia. A 39-year-old male patient was treated for
multiple myeloma and got a
bone marrow transplantation 2 years and a few months before he presented with a solitary well-circumscribed
tumor in the right middle lobe. The patient underwent surgical resection. The
tumor presented with a fibrous
capsule and consisted of mature bone trabecules. Within the
tumor, fatty tissue was seen. There were small bone spicules interpreted as areas of new bone formation and appositional growth. No
amyloid deposition, no immature epithelial tubules as in
hamartomas, and no normal lung structure as in osseous
metaplasia were seen. Within the osseous elements, a positive reaction was seen with
antibodies for
osteonectin, whereas the reaction for
calcitonin was negative. To the best of our knowledge, this is the first case of an
osteoma being reported in the lung looking like any other extraskeletal
osteoma. This
tumor might have been induced by circulating stem cells; however, due to autologous bona marrow
transplantation, this cannot be proven.