Keisuke Kato

In the present study the significance of nuclear/cytoplasmic expression of β‐catenin (CTNNB1) and mutation of the CTNNB1 gene (CTNNB1) in odontogenic tumors was examined. Six ameloblastomas (five follicular ameloblastomas and one plexiform ameloblastoma) and three malignant odontogenic tumors (one metastasizing ameloblastoma, one ameloblastic carcinoma, and one primary intraosseous odontogenic carcinoma) were investigated for CTNNB1 expression and CTNNB1 mutation. Immunohistochemically, all follicular ameloblastomas and one primary intraosseous odontogenic carcinoma exhibited focal and moderate nuclear/cytoplasmic expression of CTNNB1, whereas the plexiform ameloblastoma and the remaining two malignant odontogenic tumors had entirely membranous expression. CTNNB1 mutation at codon 40 of exon 3 was found in one of the six follicular ameloblastomas. The other five follicular ameloblastomas, the plexiform ameloblastoma, and the three malignant odontogenic tumors did not show mutation in exon 3 of CTNNB1. These findings further confirmed that CTNNB1 mutation is not frequent in ameloblastoma and malignant odontogenic tumors, although the abnormality of Wnt signaling may be associated with some of these tumors.

This study concerns the significance of nuclear/cytoplasmic expression of beta‐catenin and mutation of the beta‐catenin gene in craniopharyngiomas. Fourteen adamantinomatous type and one squamous papillary type craniopharyngiomas were studied. Histologically, 13 of 14 adamantinomatous type craniopharyngiomas showed typical features, ie mixtures of ‘palisading cells’, ‘stellate cells’, and ‘ghost cells’. In addition, ‘whorl‐like arrays’ of epithelial cells were frequently observed in the areas of stellate cells. On immunohistochemistry, all typical adamantinomatous type craniopharyngiomas showed nuclear/cytoplasmic expression of beta‐catenin predominantly in cohesive cells within the whorl‐like arrays and in cells transitional towards ghost cells, where immunoreactivity for Ki‐67 was almost absent. The cohesive cells in the whorl‐like arrays also demonstrated loss of cytokeratin isoform expression. Using direct sequencing of amplified nucleic acids, nine of the 13 typical adamantinomatous type craniopharyngiomas with nuclear beta‐catenin accumulation showed heterozygous one‐base substitution mutation of the beta‐catenin gene. The other unusual adamantinomatous type and squamous papillary type craniopharyngiomas showed no obvious nuclear/cytoplasmic beta‐catenin immunoreactivity and no mutation of the beta‐catenin gene, suggesting molecular heterogeneity. These findings suggest that the pathogenesis of typical adamantinomatous type craniopharyngioma is associated with abnormalities of Wnt signalling that act as a morphogenetic signal towards whorl‐like arrays and ghost cells rather than as simple proliferation stimuli. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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.

A case of an 8‐year‐old Japanese boy with a testicular large cell calcifying Sertoli cell tumor (LCCSCT) is presented. This report appears to be the first Japanese case of LCCSCT. The patient presented with left testicular swelling and gynecomastia. His family history was not contributory; however, his past history was remarkable for a benign myxoid tumor in the nasal cavity, which was removed at the age of 2 months. After removal of the testicular tumor, the gynecomastia disappeared gradually and no recurrence or metastasis developed during a 15 month follow‐up period. Although the tumor was initially interpreted as a Leydig cell tumor, a review of the slides after the patient’s past history of nasal myxoid tumor was revealed led us to the diagnosis of LCCSCT. An accurate diagnosis of LCCSCT is crucial because this tumor is occasionally associated with Carney complex, which can comprise various pathological conditions, including cardiac myxoma, that may be life‐ threatening. Myxoma of Carney complex has been described to occur in the heart, skin, oral cavity and breast in a wide age range, but there have been no reports referring to nasal myxoid tumor associated with Carney complex.