Nasal chondromesenchymal hamartoma of infancy: the first Japanese case report.

The first Japanese case of nasal chondromesenchymal hamartoma, a rare infantile nasal neoplasm, is presented. A 4-month-old Japanese boy was referred to our Centre because of intranasal mass and oculomotor disturbance. Radiological images showed the intranasal tumor extending to the paranasal sinus, orbit, and anterior frontal fossa. Subtotal resection and radiation therapy to residual tumor were performed. There has been no recurrence of the tumor for 13 years. Histologically, the lesion demonstrated admixture of various mesenchymal elements, including cellular spindle cell stroma with occasional myxoid change, nodules of mature/immature cartilaginous tissue, focal osteoclast-like giant cells, and erythrocyte-filled spaces resembling aneurysmal bone cyst. The histology was consistent with the findings presented by McDermott et al. 1986. Immunohistochemically, the spindle cells were positive for vimentin and smooth muscle actin. Chondrocytes in the mature cartilaginous tissue were positive for S-100 and vimentin; chondrocytes in the immature cartilaginous tissue were positive for S-100, vimentin, and smooth muscle actin. Ultrastructurally, the spindle cells showed features of either fibroblast or myofibroblast.