1. ¹Department of Pathology and Oncology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
2. ²Department of Pathology, Tokyo Medical University, Tokyo, Japan
3. ³Department of Surgical Pathology, School of Medicine, Teikyo Medical University, Tokyo, Japan
4. ⁴Department of Pathology, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan
5. ⁵Department of Pathology, Kitasato University School of Medicine, Sagamihara, Japan
6. ⁶Department of Pathology, Sahlgren University Hospital, Göteborg, Sweden

Correspondence: Hiroshi Hashimoto, M.D., Department of Pathology and Oncology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan. fax: 93-692-0189; e-mail: hiroshi@med.uoeh-u.ac.jp

Accepted 13 February 2003.

Abstract

Extraskeletal myxoid chondrosarcoma is a rare soft tissue sarcoma of uncertain histogenetic origin. Because recent reports have indicated neural-neuroendocrine differentiation in some extraskeletal myxoid chondrosarcomas, we investigated 25 tumors for expressions of microtubule-associated protein-2 and Class III -tubulin, which are major components of microtubules and specifically localized in neurons and their derivatives. Immunohistochemical expression of microtubule-associated protein-2 and Class III -tubulin was studied in extraskeletal myxoid chondrosarcomas using formalin-fixed, paraffin-embedded tissues. Cytoplasmic expressions of microtubule-associated protein-2 and Class III -tubulin were detected in 21 (84%) and 13 (52%) of the 25 extraskeletal myxoid chondrosarcomas, respectively, although the number of positively stained tumor cells varied. Expression of the Class III -tubulin gene was also assessed in two immunohistochemically positive cases by in situ hybridization using an oligonucleotide probe specific for its transcript, and both cases showed expression of Class III -tubulin transcript. Another case was examined with immunoelectron microscopy, and immunogold particles for Class III -tubulin were localized to microtubular aggregates. Our data indicate that microtubules in extraskeletal myxoid chondrosarcoma are similar to those found in neurons, further supporting the concept that neural-neuroendocrine differentiation occurs in a significant number of extraskeletal myxoid chondrosarcoma.