Pediatric SMARCB1/INI1-Deficient Undifferentiated Pancreatic Carcinoma: Presentation of an Additional Case of a Rare Tumor.

OBJECTIVE

To investigate the clinical and pathological features of pediatric SMARCB1/INI-1 deficient undifferentiated pancreatic carcinoma.

METHODS

Two SMARCB1/INI-1 deficient undifferentiated pancreatic carcinomas diagnosed from 2021 to 2024 at the Children's Hospital of Fudan University were collected. The histomorphological features, immunohistochemical results, FISH test results, and clinical treatment courses were summarized, and the potential treatment was discussed in combination with the literature.

RESULTS

Both cases were male, presenting with abdominal pain, abdominal distension, back pain, and weight loss, along with elevated serum CA125 levels. CT showed the pancreatic tail masses with heterogeneous enhancement. Microscopically, the tumor cells were arranged in nests and sheets, with focal glandular arrangement and exhibited abundant cytoplasm, vesicular nuclei, and distinct nucleoli with scant eosinophilic inclusions. Immunohistochemistry revealed CK, CK7, and CK19 expression and complete loss of INI-1 (SMARCB1) expression. The Ki-67 proliferation indices were 40%. FISH revealed SMARCB1/INI-1 gene deletion in both cases. After the surgery and chemotherapy, both patients died 42 days and 10 months after operation, respectively.

CONCLUSION

SMARCB1/INI-1 deficient undifferentiated pancreatic carcinoma is a very rare, highly aggressive malignancy in children with dismal prognosis. It should be taken in consideration when encountering a pancreatic mass to avoid misdiagnosis in routine clinical work.