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J Clin Pathol 56:666-671 doi:10.1136/jcp.56.9.666
  • Original article

Expression of smooth muscle markers in so called malignant fibrous histiocytomas

  1. T Hasegawa1,
  2. F Hasegawa2,
  3. T Hirose3,
  4. T Sano4,
  5. Y Matsuno5
  1. 1Pathology Division, National Cancer Centre Research Institute, 5–1–1 Tsukiji, Chuo-ku, Tokyo 104–0045, Japan
  2. 2Electron Microscopy Laboratory, National Cancer Centre Research Institute
  3. 3Department of Pathology, Saitama Medical School, Saitama, Japan
  4. 4Department of Pathology, University of Tokushima School of Medicine, Japan
  5. 5Clinical Laboratory Division, National Cancer Centre Hospital, Tokyo, Japan
  1. Correspondence to:
 Dr T Hasegawa, Pathology Division, National Cancer Centre Research Institute, 5–1–1 Tsukiji, Chuo-ku, Tokyo 104–0045, Japan;
 tdhasega{at}ncc.go.jp
  • Accepted 28 March 2003

Abstract

Aims: To obtain further information regarding the frequency and degree of positivity for smooth muscle markers in a large number of malignant fibrous histiocytomas (MFHs), as an aid to accurate diagnosis.

Method: The immunohistochemical features of 100 MFHs were studied and the results were compared with those for 30 leiomyosarcomas. Eighteen cases of MFH with smooth muscle actin (SMA) positivity were examined ultrastructurally.

Results: Immunoreactivity for smooth muscle markers, such as desmin, SMA, muscle specific actin (MSA) and h-caldesmon (HCD), which is a specific marker for smooth muscle cells and their tumours, was found in 28, 30, 29, and 29 of 30 leiomyosarcomas. Immunoreactivity for desmin, SMA, MSA, and HCD was found in 17, 30, 14, and two of the MFHs. On electron microscopic examination, approximately half of the cases contained a varying proportion of myofibroblastic cells. The others had only fibroblastic or undifferentiated tumour cells. At least 30% of the cases were found to display features consistent with limited smooth muscle or myofibroblastic differentiation.

Conclusion: A large subset of so called MFH in fact shows poorly differentiated smooth muscle or myofibroblastic features, and perhaps such tumours should be regarded as pleomorphic leiomyosarcomas and/or pleomorphic myofibroblastic sarcomas.

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