In this study, the expressions of smooth muscle-specific proteins (desmin, alpha-smooth muscle actin, basic calponin and the smooth muscle myosin heavy-chain isoforms of SM1 and SM2) in three parent and four cloned neuroblastoma cell lines, composed of S-type cells, were examined by indirect immunofluorescence, Western blot and/or by reverse transcription-polymerase chain reaction (RT-PCR).
It is one of the pediatric small round blue cell tumors, characterized by strong membrane expression of CD99 in a chain-mail pattern and negativity for lymphoid (CD45), rhabdomyosarcoma (myogenin, desmin, actin) and neuroblastoma (neurofilament protein) markers.
Histopathological findings showed neuroblastoma and immunohistochemical results were as follows: actin(-), CD34(-), CD99(-), CK(-), CgA(+), desmin(-), EMA(-), Ki-67(+, approximately 1%), NSE(+), S-100(+), Syn(+), and vimentin(-).
Both of these tumors exhibited "large cell neuroblastoma" histology with enlarged, uniquely open nuclei and nucleolar hypertrophy, along with "aberrant" desmin expression.