What is the difference between a polyp and a papilloma?

Question

I hope the question was clear because I have got nothing to clarify it with. I was reading Robbins and its Neoplasia chapter when that confused me a bit. Can anybody clear this up for me? According to Robbins:

Papillomas are benign epithelial neoplasms growing on any surface, that produce microscopic or macroscopic fingerlike fronds.

A polyp is a mass that projects above a mucosal surface... to form a macroscopically visible structure.

I understood these sentences quite good enough but what is the fundamental quality that sets them apart? I still am not confident regarding their differences (and cannot differentiate them, say, on a patho slide) A little bit of histology here would be really helpful.

Answer 1

A polyp is a broad term that is defined only by its macroscopic appearance. So, I'll just repeat the definition provided in the question:

A polyp is a mass that projects above a mucosal surface... to form a macroscopically visible structure.

Polyps can be categorized by their microscopic (type of cell) characteristics, for example:

Papillomas are benign epithelial neoplasms growing on any surface, that produce microscopic or macroscopic fingerlike fronds.

Examples of other subtypes of polyps (based on microscopic differences) are adenomas, inflammatory and hyperplastic polyps, hamarthomas, etc.

So, papilloma is a type of polyp.