Discussion:
The pancreatic tumours in paediatric population are rare. The incidence of malignant pancreatic tumours in children was 0.18 per 1,00,000 people in United State of America in 2008.5 The tumours may be endocrine, exocrine or sarcomas.10,11 The rarity of these tumours limit our understanding of the pathophysiology and the clinical course and hence the appropriate management of the tumours. There are no standardised protocols and hence the management has to be individualised according to the given conditions.9
Among the paediatric pancreatic malignancies pancreatoblastoma is the most common tumour in children less than 10 year of age. The usual age of presentation is 4- 5 years.3 They usually tend to present as large abdominal masses followed by pain in abdomen.12 Serum alpha feto protein is elevated in 68% to 94% of patients. Although it is of no diagnostic value, it has utility in terms of marker of response to chemotherapy and of recurrence in postoperative period.8 The treatment is complete resection of the lesion.13 The resection may include excision, pancreaticoduodenectomy, and distal pancreatectomy depending on the site of the lesion. For unresectable lesions neoadjuvant chemotherapy in the form of PLADO is generally recommended as these tumours have shown sensitivity to this regimen.8,9Histopathologically they exhibit dense cellularity with characteristic “squamoid corpuscles”.2 The 15 year survival rate in children is reported to be 61%.5
Acinar cell carcinomas are rare pancreatic neoplasms accounting for 1-2% of all pancreatic malignancies. In children the incidence is 7.2% of all pancreatic malignancies.14 Acinar cell carcinomas are generally seen in children more than 10 years of age.15 The most common site for acinar cell carcinoma is tail (41% of cases) followed by head (32% of cases) of the pancreas. They usually present with large palpable masses and abdominal discomfort.14 Grossly they have circumscribed expansile growth pattern and invasion of common bile duct is less frequent. Jaundice is rarely seen.12 The classic “Lipase hypersecretion syndrome” has not been observed in children.16 Serum alpha feto protein has been observed to be elevated in all patients of acinar cell carcinomas. It has been hypothesized that alpha feto protein production in pancreatic tumours is related to acinar differentiation.6 Acinar cell carcinoma in children has overlapping features with pancreatoblastoma and may closely resemble neuroendocrine tumours. Squamous nests which are absent in acinar cell carcinoma are considered the feature essential for the diagnosis of pancreatoblastoma.2
Although pancreatoblastoma is predominantly a tumour of infancy and childhood and acinar cell carcinoma is of adults, exceptions to the above are well documented.17,18 Acinar cell carcinoma occurring in childhood has considerable clinical as well as pathological overlap making the diagnosis difficult. Often the diagnosis is made by pathologist on the basis of the age of the patient.18In our patient the same has happened. A thorough literature search revealed only three cases of acinar cell carcinoma in 4 year old child and less.19, 20 To the best of our knowledge this is only the fourth case of acinar cell carcinoma in such a young child. The preoperative diagnosis in our patient was pancreatoblastoma and as imaging features suggested the non resectability the child was subjected to neoadjuvant chemotherapy to which he had responded. Surgically the resection was satisfactorily complete with negative margins. Radiotherapy has limited role but as our child had tumour spill he is scheduled for the radiotherapy. As mentioned earlier the therapy has to be individualized for the best outcome.