Neuroblastomas are the most common extracranial solid tumors seen in children. Metastatic disease is found in more than 50% of children at diagnosis. Childhood NBs usually originate in the abdomen (adrenal glands and extraadrenal sites), thoracic structures (especially posterior mediastinum) and sympathetic chain. Moreover, bone, bone marrow, liver, cutaneous tissue, as well as pulmonary and brain parenchyma can also be involved as a result of hematogenous spread [1
Anterior mediastinum and duramater involvement is extremely rare. NBs localized in anterior mediastinum in adult patients have been reported [5-10]. A NB of the thymus in an adult patient, accompanied by syndrome of inappropriate secretion of ADH has also been documented . Brain metastases from extracranial neuroblastoma are rare. They are generally produced by direct extension from metastatic lesions of the skull or dura. The incidence of leptomeningeal or central nervous system parenchymal disease in patients who experience disease recurrence ranges from 1% to 16% [11-13]. In the literature, it was reported that out of a total of 14 NB patients with brain involvement, only one of them had duramater disease . In our case, with advanced disease at diagnosis, metastatic involvement included the anterior mediastinum, dura mater as well as numerous subdural tumors.
Flow-cytometry is not a routine method used during diagnosis of NB. But in recent years, this method has demonstrated its value in treatment follow-up and for verification of residual mass by confirming NB cells circulating in peripheral blood and bone marrow [2,3]. It is known that NB cells express CD45(-)/CD44(+)/CD56(+)/CD81(+)/CD9(+) antigens [2,3,15,16]. It is an effective method to rapidly detect NB cells in bone marrow . In our case, analysis of the bone marrow sample with flow-cytometry revealed expression of CD45(-)/CD44(+)/CD56(+) in NB cells. After second cycle of the chemotherapy, CD45(-)/CD44(+)/CD56(+) positivity was 5%.
Prognostic factors of NB are stage, age, N-myc, high VMA level, histology . However, CD44 expression in flow-cytometry is also a good prognostic criterion, independent from the stage, age and N-myc amplification [17,18]. Our patient had poor prognostic factors such as age, stage and elevated urinary VMA. However, response to the treatment was good. We think that our patients response to the therapy is related to CD44 expression.
In conclusion, NB cases involving the anterior mediastinum, duramater and brain involvements are extremely rare. Despite the presence of advanced disease, we think that CD44 expression is an indicator of good prognosis. The flow-cytometry may be helpful for diagnosis and followup of NB with bone marrow involvement.