After a bit of digging, possibly gall?

Yes. Crown gall, a systemic disease for which there is no cure, is a common bacterial infection in F benjamina. The bacterial cells attach to cells which conduct water in the xylem and disperse in the plant through the xylem. An accumulation of the cells which have undergone unorganized cell division is the underlying cause of the masses that resemble callus tissue. You noticed a lack of vitality because the gall(s) hamper movement of water/ nutrients through affected tissue, which affects normal growth distal to the affected area.
As the galls increase in size, they shed bacterial cells into the soil/ soil solution and the cells exit the pot as the effluent moves through the drain hole. The cells can live for up to 2 years on roots and in mineral soils. The bacterium can be spread by your hands, tools, pots, puddles, irrigation or rainwater, .........

I know you don't want to, but you probably should destroy the tree and make an effort to disinfect anything that might provide a pathway by which your other or future trees might be infected.

Al

That is unfortunate but i will destroy it if nothing can be done.

thanks for your input!