Ficus stem bumps

John Duarte brought in this specimen of a twig and leaves of a (presumed) ficus. The homeowners were thinking that the spots on the stem were a scale insect. I don’t think so. In looking at it, and thinking it over, I wondered if the spots were just a natural part of the plant. If so, then what advantage would these darkish bumps provide the tree? And examination revealed that some spots had cracked open, or had a rotted out center, suggesting this may not be the case.

The photos show the leaves, which look fine, and there is along sequence of pictures, starting at a leaf and working down to older stem wood. The fresh growth has no bumps, and when the first bumps appear, they are small. Only further down the stem do the bumps turn dark and show evidence of decay.

I wonder, then, if these dark bumps are a fungal or bacterial infection. Other than their presence, the plant looks perfectly fine. It reminds me of the Eutypella bumps on buckeye.