[Morphology and immunohistochemical characteristics of hepatic primary and metastatic malignant spindle cell tumors].
OBJECTIVE
To investigate the morphology and immunohistochemical characteristics of hepatic primary and metastatic malignant spindle cell tumors, and to conclude the diagnostic and differential diagnostic criteria for these morphologically similar tumors.


METHODS
Forty-six specimens of hepatic spindle cell tumors. 20 primary tumors (43.4%), including 3 cases of sarcomatoid carcinoma (6.5%), 11 of angiosarcoma (23.9%), 2 of epithelioid hemangioendothelioma (5%), 1 of spindle cell carcinoid (2.2%), and 3 of undifferentiated sarcoma (6.5%). and 26 metastatic malignant tumors (56.5%), including 20 cases of gastrointestinal stromal tumors (GIST, 43.4%), 3 of leiomyosarcoma (6.5%), 2 of malignant peripheral never sheath tumor (4.3%), and 1 of meningeal hemangiopericytoma (2.2%), resected during operation or collected during imaging-mediated liver puncture underwent hematoxylin-eosin staining, SP staining, and EnVision immunohistochemical staining.


RESULTS
Either primary or metastatic tumors showed extensive overlapping in histopathologic appearance, and hemangiopericytoma-like structure was the predominant pattern, which could be seen in nearly every kind of hepatic spindle cell tumors. The morphology of GIST was the most complex. Two or three entirely different kinds of structure could be seen in one specimen of GIST, especially in the resected ones. Most stromal tumor cases were CD117 positive, and existed the condition that the primary tumor was positive and the metastatic tumor was negative or vice versa or one part of specimen was positive but other part was negative. Leiomyosarcoma was immunoreactive to smooth muscle specific antigen (SMA), malignant peripheral nerve sheath tumor was immunoreactive to S-100 protein and neurofilament (NF), and both were CD117 negative. Angiosarcoma and epithelioid hemangioendothelioma expressed different immunoreactivity to CD31, CD34 and factor VIII related antigen. Sarcomatoid carcinoma was positive for CK and vimentin. Spindle cell carcinoid was positive for CK and neuroendocrine markers, such as synaptophysin and chromogranin A.


CONCLUSION
Primary angiosarcoma is the most common form of primary spindle cell tumor in liver, and metastatic GIST is predominant in hepatic metastatic spindle cell tumors. A penal of immunohistochemical markers is necessary for the final diagnosis of these tumors because of the complexity and similarity of different tumors of this kind.