Combining Multiple cells data into 1 cell

Hi, Thanks for checking my thread. I have an excel sheet with Part numbers in Column A and their respective values in column B.. The problem is there are some Part numbers that have multiple values in column B and I want to combine them to 1 cell...
Example

Column A----------Column B
SKU---------- Category
123LM---------- Antennas:MC connector
123LM---------- Antennas:2.4GHz typical WiFi:Omni-Directional
123LM---------- Antennas:2.4GHz typical WiFi:Omni-Directional:Magnetic-mount


I need...

Column A----------Column B
123LM---------- Antennas:MC connector;Antennas:2.4GHz typical WiFi:Omni-Directional;Antennas:2.4GHz typical WiFi:Omni-Directional:Magnetic-mount

so these 3 values of 123LM are combined in 1 cell with a Semi Colon between it's 3 different values...
There are hundreds of lines of data so it is not possible to do it manually..
I shall be very thankful if someone solves this problem of me..
Attached is an example sheet..

Thanks a lot