Desmoplastic small round cell tumour of the abdomen

Clinical History

We present a case of a 21-year-old man who reported weakness, anorexia and a palpable sense of mass in the right upper abdominal quadrant. Physical examination showed a palpable solid mass in periumbilical region and right abdominal flank.

Imaging Findings

CT yielded a large peritoneal soft-tissue mass with punctate calcifications. The mass displaced bowel loops and compressed the right distal ureter conditioning a hydronephrosis grade II. In the lower pelvis, between the rectum and urinary bladder, another similar mass could be seen. Liver metastases, peritoneal plaques, moderate ascites, and celiac, periportal, lumboaortic and iliac lymphadenopathies were also present. In addition, chest CT demonstrated mediastinal lymph node and lung metastases.
The samples of an US-guided core needle biopsy of the mass located in abdominal lower right quadrant were sent for analysis to the pathology department.
A CT follow-up after 12 months of chemotherapy according to the scheme VAC-IE (vincristine, adriamycin, cyclophosphamide, etoposide and iofosfamida) showed a marked size reduction of the intraperitoneal and pelvic mass and a significant decrease in number of the metastases in liver, lung, mediastinal and abdominal lymph nodes.

Discussion

Desmoplastic small round cell tumour is an aggressive neoplasm that tends to occur in adolescent and young adult males [1-5]. It usually affects serous membranes of peritoneum, pleura or testicles; less common locations are lung, kidney, central nervous system, and ovaries [1-5].
The clinical manifestations are nonspecific, abdominal pain and palpable mass sense being the most prevalent symptoms. Because of the nonspecific manifestations, patients are often referred for diagnostic imaging [1,2,4,5]
The main CT finding is the presence of solitary or multiple peritoneal soft-tissue masses, with heterogeneous density and without apparent organ of origin [1,2,4,5]. Areas of necrosis and punctate calcifications are additional features. Liver metastases, peritoneal implants and lymphadenopathies can be present at the time of diagnosis [1-5]
If the mass is located in the retrovesical region [3], the presence of liver and lymph node metastases and ascites is more often found due to the peritoneal fluid circulation. Lung or bone metastases and extraabdominal lymph node metastses are rare. In advanced stages hydronephrosis secondary to extrinsic compression may result [3,4].
The MRI findings of desmoplastic round small cell tumour are multiple peritoneal masses with intermediate signal intensity on T1-weighted sequences and hyperintense signal on T2-weighted sequences; the contrast enhancement is poo [5]. The advantage of MRI over CT is the capability to detect small peritoneal metastases and local invasion of abdominal organs.
A definitive diagnosis always requires histology. Biopsy is performed via US or CT guidance.
Treatment consists of radical surgery with systemic chemotherapy and adjuvant radiotherapy [2]. The prognosis is unfavourable, showing a high rate of recurrence and high mortality. The median survival rate is 17 months [2,3].

Differential Diagnosis List

Final Diagnosis

Desmoplastic small round cell tumour of the abdomen

URL:	https://www.eurorad.org/case/9316
DOI:	10.1594/EURORAD/CASE.9316
ISSN:	1563-4086