Dear Editor,

We read the report on ‘Primary Hepatic Lymphoma Mimicking Cholangiocarcinoma’ published in the July 2017 issue of the Oman Medical Journal with great interest.1 In fact, both primary hepatic lymphoma and cholangiocarcinoma might result in highly similar clinical presentation and are sporadically mentioned in the literature.2–4 Here, we would like to discuss a possible way to differentiate between both disorders using serum alkaline phosphatase (ALP) isoenzyme electrophoresis, a simple laboratory test. Based on a previous report from Thailand, the significant elevation of specific fast liver isoenzyme of ALP can be observed in malignant tumors of the biliary tract.5 For primary hepatic lymphoma, additional atypical bone-like isoenzyme of ALP might be observed.6 Since the ALP isoenzyme test can be easily done and provide the result within a short time, it should be considered a tool to help confirm the diagnosis of cholangiocarcinoma.

references

1. 1. Forghani F, Masoodi M, Kadivar M. Primary Hepatic Lymphoma Mimicking Cholangiocarcinoma. Oman Med J 2017 Jul;32(4):335-338.
2. 2. Durham C, Jaiswal D, Wong L. Bile duct lymphoma disguised as cholangiocarcinoma. Proc (Bayl Univ Med Cent) 2017 Apr;30(2):190-191.
3. 3. Hwang S, Song TJ, So S, Jeon MK, Oh EH, Kwon BS, et al. Primary Biliary Mucosa-associated Lymphoid Tissue Lymphoma Mimicking Hilar Cholangiocarcinoma. Korean J Gastroenterol 2016 Aug;68(2):114-118.
4. 4. Elbanna KY, Al-Shieban S, Azzumeea F. Primary follicular lymphoma of the common bile duct mimicking cholangiocarcinoma. J Clin Imaging Sci 2014 Dec;4:72.
5. 5. Paritpokee N, Tangkijvanich P, Teerasaksilp S, Wiwanitkit V, Lertmaharit S, Tosukhowong P. Fast liver alkaline phosphatase isoenzyme in diagnosis of malignant biliary obstruction. J Med Assoc Thai 1999 Dec;82(12):1241-1246.
6. 6. Belland L, Visser L, Poppema S, Stinson RA. Characterization of the alkaline phosphatase expressed on the surface of a Hodgkin’s lymphoma cell line. Enzyme Protein 1993;47(2):73-82.