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.