A giant pancreatic serous microcystic adenoma with 20 years follow-up.

BACKGROUND AND AIMS: There is only little information about the spontaneous course of large pancreatic serous tumours. We followed up a white woman with a giant serous microcystic adenoma over more than 20 years. CASE REPORT: At first clinical presentation, in 1986, the tumour measured 4.5 cm in diameter. Two years later, it measured 6 cm and was considered as non-resectable at laparotomy. A biopsy was obtained, and the tumour was diagnosed as lymphangioma, based on hematoxylin and eosin-staining. During the follow-up, the tumour progressively increased in size, measuring 12 cm in diameter in 1993 and 17 cm in 2000. Thus, an average growth rate of 0.83 cm per year was calculated. Unspecific abdominal discomfort and pain were the leading clinical symptoms. A colonic resection was necessary because of compression by the tumour in 1993. Portal hypertension was detected at laparotomy. Finally, the initial biopsy specimen was re-evaluated, using immunohistochemistry, and the final diagnosis of a serous microcystic adenoma was made.
CONCLUSION: This unique case demonstrates that the spontaneous course of serous microcystic adenoma of the pancreas may be favourable even with huge tumour size and that immunohistochemistry may prove a valuable tool for differential diagnosis of cystic pancreatic lesions. Due to their size and progressive, space-occupying growth, these biologically benign tumours may cause injury to adjacent organs and thus clinical symptoms. For this reason, curative surgical resection is the treatment of choice for this tumour entity except for small, asymptomatic lesions, which do not require intervention. When radical resection is impossible, palliative surgery may improve the quality of life for several years. The risk of malignant transformation seems to be low even in the long-term course.