Unusual ultrastructural findings in giant-cell fibroblastoma

We report on a 4-year-old boy with recurrent giant-cell fibroblastoma of the right nasal genal region. Histologic examination revealed that both lesions were constituted of spindle and stellate cells and a minor amount of multinucleated giant cells in a myxoid stroma containing cisternal-like spaces. Immunohistochemical examination revealed positivity for vimentin in both cellular components. Ultrastructural examination showed, in some spindle and multinucleated cells, two kinds of intracellular crystalline inclusions, located, respectively, in the cisternae of the rough endoplasmic reticulum and, apparently free, in the cytoplasm. To the best of our knowledge, this case, unusual for its location, is the first example of giant-cell fibroblastoma bearing intracellular crystalline inclusions.