Intraabdominal DSRCT has rarely been reported in adolescents and young adult males, and few long-term survivors have been described and the survival prognosis following the diagnosis is an average of 23 months [2
]. Due to the highly aggressive nature and diffuse spread of the DSRCT, systemic chemotherapy has been used as the initial treatment along with debulking surgery. Lal et al. [3
] achieved an over 90% reduction of the tumor bulk in 71% of their patients and demonstrated a significant survival benefit, thus suggesting the benefit of aggressive surgical resection. By contrast, Livaditi et al. [4
] reported that even radical surgical efforts were palliative with a dismal outcome despite all therapeutic modalities. It was impossible in the case reported here to achieve a large volume reduction at surgery because of the massive retroperitoneal involvement. Whether it is worth sacrificing major organs such as the liver and pancreas for cytoreductive surgery in patients with DSRCT is debatable.
Primary gastric cancer, although rare, has been reported sporadically in children and the reported incidence is about 0.1% [5
]. However, DSRCT of the stomach is extremely rare; only one case has been previously reported in children [5
]. The rarity of this condition along with the inconspicuous pathology led us to misdiagnose as stage IV gastric cancer before surgery. We suggest that, when poorly differentiated malignancies of the stomach are being considered, DSRCT should be in the differential diagnosis, especially among adolescent and young adult males. Moreover, since DSRCT can form a mass along the whole GI tract, thus mimicking a primary GI tract tumor, DSRCT should be included in the differential diagnosis of primary GI tract tumors in children.
DSRCT typically display clusters or nests of small round cells lying in a hypocellular, desmoplastic, collagenous stroma and this is a helpful diagnostic feature. In immunohistochemical staining, the DSRCT is usually positive for desmin (dot-like expression) and cytokeratin [6
]. The case reported here satisfies the typical pathological and immunohistochemical staining profiles and we could make the diagnosis of DSRCT, which was impossible before laparotomy.
The reciprocal translocation t(11;22)(p13;q12) is unique to the DSRCT and confirms the diagnosis [7
]. The translocation fuses two specific genes: the Ewing sarcoma
gene (found in Ewing's sarcoma) and the Wilms tumor 1
gene (found in Wilms' tumor), and the resultant chimera protein is thought to act as a transcriptional regulator [8
]. This transcriptional factor is known to regulate the expression of specific target genes, and the dysregulated expression of the target genes is related to the invasiveness of the DSRCT [9
]. Recently, connective tissue growth factor (CCN2) that is highly expressed in DSRCT, has been found to regulate the tumor cell growth, matrigenesis, and angiogenesis of this tumor [10
]. As conventional multimodal treatments fail to improve survival, future treatment should include specific targeted treatment focusing on these cellular regulatory mechanisms.
"Initially responsive but soon refractory to the treatment and rapidly progressive" depicts the clinical behavior of the DSRCT [4
]. The case reported here showed an initial treatment-response of the gastric mass after the neoadjuvant chemotherapy; however, the residual tumors remained nearly unchanged postoperatively after adjuvant chemotherapy with CCG 7881B. The tumors are likely now in a refractory phase and will soon show rapid disease progression, eventually leading to the death of this patient.
In summary, a patient with intraabdominal DSRCT mimicking a gastric cancer is presented in this report. The diagnosis was determined after laparotomy. The diffuse intraabdominal spread made it impossible to extirpate the lesions completely. Although post-operative chemotherapy was provided and the patient is now alive with residual disease, the prognosis is dismal.