D2-40-positive solitary fibrous tumors of the pleura: diagnostic pitfall of biopsy specimen

Pathology International. 2007 Sep;57(9):618-21. [Link]

Naito Y, Ishii G, Kawai O, Hasebe T, Nishiwaki Y, Nagai K, Ochiai A.

Pathology Division, Research Center for Innovative Oncology, National Cancer Center Hospital East, Kashiwa, Chiba, Japan.


Solitary fibrous tumor of the pleura (SFTP) is an uncommon spindle-cell neoplasm and is sometimes confused with other spindle-cell tumors, such as sarcomatoid mesotheliomas. D2-40 is a new monoclonal antibody recognizing podoplanin and several studies have confirmed the reliability of D2-40 in the diagnosis of pleural mesothelioma. The authors encountered a case of SFTP that was immunoreactive to D2-40. A 56-year-old woman was admitted to hospital because of an abnormal shadow on a chest X-ray. Percutaneous needle biopsy indicated a spindle-cell tumor showing positive immunoreactivity for CD34, supporting the diagnosis of SFTP. However, the tumor was also immunoreactive to D2-40 and thus malignant mesothelioma could not be ruled out. The tumor was surgically resected to make a definitive pathological diagnosis. The tumor had a patternless architecture and immunohistochemistry was positive for CD34 and D2-40 but was negative for calretinin and cytokeratin 5/6. Therefore a pathological diagnosis of SFTP was made. An additional six tumors diagnosed as SFTP were also tested. Focal immunoreactivity to D2-40 was positive in three out of seven cases, including the first case. Care is required in diagnosing biopsy specimens of D2-40-positive pleural spindle-cell tumors, especially in making the differential diagnosis between SFTP and malignant mesothelioma.