5-Discussion
Pancreatic metastasis is rare, accounting for only 2% of all pancreatic
cancer8. The primary tumors that metastasize
frequently to the pancreas are lung cancer, renal cell carcinoma, breast
cancer, melanoma and colon cancer9.
Ewing sarcoma is a rare bone tumor and depending on whether metastases
were present at diagnosis, patients with ESFT have considerably
different five-year overall survival rates (OS) ranging from 70% if
localized to 9–41% for metastatic disease10.
Hyma et.al reviewed a 39 cases of ESFT involving the pancreas, with only
four of them being metastatic lesions11. The 4 cases
were younger than 30 years of age, with two of them testing positive for
CD 99 and one testing positive for PAS in terms of pathologic features.
There is also a male predominance with only one female case.
A review done by Saif et.al showed no gender predilection in Ewing
sarcoma /primitive neuroectodermal tumour (ES/PNET) with the majority
diagnosed at their teenage years with disseminated disease at the
diagnoses12.
The diagnosis of pancreatic metastases can be made safely and
effectively with endoscopic ultrasonography (EUS) and confirming the
diagnosis using immunohistochemistry9. Out of the 39
cases described in the literature, CD99 is the most frequently reported
marker linked to ES. Other related markers that are less precise are
synaptophysin, vimentin, and neuron-specific
antigen11.
Radiation, chemotherapy, and surgical resection were used to treat these
individuals; however, the prognosis was poor with two resulting deaths
from the disease. Similarly, our case was a young male patient with
positive CD 99 in terms of pathologic features.
The prognosis for ESFTs has significantly improved after multiagent
chemotherapy was added to surgery and/or radiation treatment. Children
with localized illness who get combined-modality treatment have a 65%
to 70% progression-free survival rate (PFS)13. The
EURO-EWING 99 trial demonstrated that patients who received local
treatment for both the primary and metastatic disease had a three-year
event-free survival rate that was significantly higher compared to
patients who only received local treatment for the primary or metastatic
disease14.
Another differential diagnosis in young patients is small cell
neuroendocrine carcinoma due to the similarity in morphological
characteristics, imaging and immunohistochemistry which can delay the
proper therapy. Hence, to confirm the diagnosis, molecular study should
be employed.
In conclusion, we present a rare case of ES metastasis to the pancreas
in a 38-year-old male with prior diagnosis and treatment of ES of the
left foot unresponsive to chemotherapy. Our case emphasizes the rarity
of pancreatic ES metastases, since only four previous cases have been
documented in the literature. Pancreatic metastasis can be diagnosed
with immunohistochemistry stain, with CD99 being the most frequently
found marker linked to ES.
Figure 1 legend: Well circumscribed mass measuring 14 mm at the
junction of the body and tail of the pancreas (white arrow).
Figure 2 legend: Figure 2a :13 mm cyctic lesion obstructing the
Wirsung duct, which is dilated upstream.
Figure 2b: FNA needle 22G inside the lesion.
Figure 3 legend: Figure 3a: Small round blue cell in H&E
stain.