96. Jahrestagung der Deutschen Gesellschaft für Pathologie e. V ...

Abstracts
Consequently, here was analyzed the presence of CT antigens in a series
of fetal thymic tissues.
Methods. Archival thymus tissue from 40 cases (week 15–42) were available
for analysis. Immunohistochemistry employing the following mAbs
(to the following CT antigens) were used: MA454 (MAGE-A1), 57B
(MAGE-A4), E978 (NY-ESO-1), #26 (GAGE), CT7-33 (CT7), and CT10#5
(CT10).
Results. Expression of the tested CT antigens was highly variable. NY-
ESO-1 remained completely negative. MAGE-A1 was solely found in
single cells of three thymi. CT7 and CT10 were present in 10 and 11 thymi
respectively, both showing solely focal staining. GAGE and MAGE-A4
were most abundantly expressed: GAGE was present in 22/40 and MA-
GE-A4 in 27/40 tissues; both antigens displaying larger groups of positive
cells. For all tested antigens, immunopositive cells were restricted to the
medulla and were exclusively epithelial cells. There was not predilection
of any gestational age for any of the tested antigens.
Conclusions. The present study shows that -irrespective of fetal development/gestational
age- several CT antigens are consistently present in fetal
thymus, albeit to a variable extent. Expression is restricted to thymus
epithelial cells and ranges from a few cells to larger groups of cells; GAGE
and MAGE-A4 are most abundantly present. Interestingly, there was no
NY-ESO-1 expression in any of the tested thymi. These data complement
serological data in cancer patients which show rare immune responses
to those antigens, which were highly expressed in our series of thymus
tissues. NY-ESO-1, however, is the most immunogenic antigen in cancer
patients. The lack of NY-ESO-1 expression in fetal thymus could be the
cause of lacking pre-existing immunotolerance to NY-ESO-1 rendering
cancer patients more sensitive to the presence of NY-ESO-1 in cancer tissue
and/or vaccine applications.
SO-050
Hepatobiliary rhabdomyosarcoma in a 2-year-old: a case report
K . Wieczorek1 , G . Fitze2 , R . Knöfler3 , G . Hahn4 , G . Baretton1 1University Hospital “Carl Gustav Carus”, TU Dresden, Department of
Pathology, Dresden, 2University Hospital “Carl Gustav Carus”, TU Dresden,
Department of Pediatric Surgery, Dresden, 3University Hospital “Carl Gustav
Carus”, TU Dresden, Department of Pediatric Oncology, Dresden, 4Univer sity Hospital “Carl Gustav Carus”, TU Dresden, Department of Radiology,
Dresden
Aims. Although representing the most common sarcoma in the pediatric
patient, rhabdomyosarcomas of the liver account for only 0.8% of all
rhabdomyosarcomas, and 1% of all liver tumors. Unless they present in
the characteristic setting of a botryoid mass in the biliary tree, they are
difficult to diagnose, as they share many histomorphologic similarities
with undifferentiated embryonal sarcomas of the liver. This case report
summarizes clinical data and histomorphologic and immunohistochemical
features of a hepatobiliary rhabdomyosarcoma in a 2-year-old boy.
Methods. A 2-year-old boy presented to an external hospital with severe
jaundice and hepatomegaly. Initially, an infectious process was suspected,
and the boy was referred to the pediatrics department of the Dresden
university hospital. MR imaging revealed a very large liver tumor and
multiple metastases in the lung and bone. The gallbladder and the biliary
tree were initially not visible due to the size and partially cystic appearance
of the tumor. A biopsy of the liver was taken.
Results. Liver biopsy showed a malignant mesenchymal neoplasia consisting
of primitive round to spindled cells with multiple mitoses. A
zonal architecture was noticed around small bile ducts. Very few (