Phosphaturic mesenchymal tumor, nonphosphaturic variant, causing fatal pulmonary metastasis

Kazuyoshi Uchihashi, Aki Nishijima-Matsunobu, Atsuji Matsuyama, Fumio Yamasaki, Tsuyoshi Tanabe, Tetsuji Uemura, Naoko Aragane, Mai Yakushiji, Mihoko Yamamoto, Shigehisa Aoki, Shuji Toda

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


Phosphaturic mesenchymal tumors of the mixed connective tissue type (PMT-MCTs) are rare neoplasms, most of which are benign and cause tumor-induced osteomalacia because of overproduction of a phosphaturic hormone, fibroblast growth factor 23 (FGF23). This entity may have been unrecognized or misdiagnosed as other mesenchymal tumors, such as giant cell tumor, hemangiopericytoma, and osteosarcoma. Ten percent of these tumors, without phosphaturia, were diagnosed only by their histologic features. We report here the first case of malignant PMT-MCT, nonphosphaturic variant, resulting in fatal multiple lung metastases. Chondromyxoid matrix with "grungy" calcification, multinucleated giant cell proliferation, and expression of FGF23 mRNA (reverse transcription- polymerase chain reaction) and fibroblast growth factor 23 protein (immunohistochemistry) were seen in the primary and recurrent tumors of the right foot. The lung metastases showed flocculent calcification and FGF23 protein expression as well as giant cell proliferation. This unique case highlights the need for careful histologic assessment of PMT-MCTs, especially the nonphosphaturic variant, and the need for recognition of its rare malignant behavior.

Original languageEnglish
Pages (from-to)2614-2618
Number of pages5
JournalHuman Pathology
Issue number11
Publication statusPublished - 11-2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pathology and Forensic Medicine


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