Soft tissue tumor is defined as a tumor occurring in voluntary muscles, fat. fibrous
tissue, along with the vessels serving these tissue and peripheral nervous system. It is
difficult to make a diagnosis by conventional microscopic observation because of their
pleuripotentiality and similar growth characteristics.
Although their morphological findings of turners are similar to one another, their
clinical courses, treatment and prognosis are different. So early, correct diagnosis and
proper treatment are necessary. The present studs is aimed to evaluate a value of
immunoperoxidase staining to make definite diagnosis of soft tissue tumors and its
application to surgical pathology.
The material consisted of 106cases of fibrohistiocytic tumors and malignant soft tissue
tumors which are morphologically similar to malignant fibrohistiocytic tumors for 5
years period lasting from 1980 to 1984 at the Department of Pathology, Yonsei
University College of Medicine. After the classification of fibrohistiocytic tumors by the
Enzinger(1983), clinical findings were reviewed and peroxidase antiperoxidase(PAP)
method with α1-antichymotrypsin was done in 15 cases of all
fibrohistiocytic tumors. Other soft tissue turners which were difficult to differentiate
from MFH by light microscopic observation were liposarcoma, rhabdomyosarcoma,
fibrosarcoma and malignant schwannoma. These 21 crises of tumors including MFH
were stained with PAP method for α1-antichymotrypsin, S-100 protein
and myoglobin.
Results obtained were as follows :
1) The Gases on study consisted of 19 cases of malignant fibrous histiocytoma, 2
dermatofibrosarcoma protuberans, 45 fibrohistiocytic tumors and 11 other benign
fibrohistiocytic tumors.
2) The male to female ratio was 1 : 1.8 in benign and intermediate group of
fibrohistiocytic tumor, but 2.2 : 1 in malignant histiocytic tumor.
3) Most cases of benign fibrohistiocytic tumors were occurred in 4th and 5th decade
of life. Intermediate and malignant fibrohistiocytic tumors were mostly found in late
adult life and their mean age was 43.6 year.
4) The most common sites were trunk and both extrimities in benign fibrohistiocytic
tumors (88.9%), but head, neck and lower extremities in MFH (78.9%). Two cases of
dermatofibrosarcoma protuberans were occurred In trunk and upper extremity.
5) The PAP stain for α1-antichymotrypsin was done in 15 cartes of 77
fibrohistiocytic tumors which included MFH, dermatofibrosarcoma protuberans, xanthoma,
xanthofibroma, dermatofibroma and juvenile xanthogranuloma. All fibrohistiocytic tumors
except one case of dermatofibroma showed variable degree of positivity to α
1-antichymotrypsin. The positivity of α1-antichymotrypsin
revealed no significant difference according to differentiation of the tumors, such as
benign, intermediate and malignant.
6) The PAP stain for α1-antichymotrypsin revealed diffuse positivity in
all cases of MPH and also in a case of malignant schwannoma, fibrosarcoma,
liposarcoma and rhabdomyosarcoma, but myoglobin and S-100 protein were negative. In
three cases of leiomyosarcoma, two of rhabdomyosarcoma and three of malignant
schwannoma, α1-antichymotrypsin, S-100 protein and myoglobin were
negative, although a few positive tumor cells were present, which may be considered as
metatypic differentiation. Another possibility of this discordance was loss of antigenicity
by improper procedure of paraffin embedding and poor differentiation of tumor cells.
In summary, PAP method for specific tumor marker is important for proper diagnosis
of soft tissue tumors. and application to surgical pathology.
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