Polyps of Peutz-Jeghers syndrome are usually non-neoplastic hamartomas.  On microscopic histopathological analysis, polyps have the following characteristic findings: 
Frond-like polyp with all three components of mucosa: Muscosal epithelium (melanotic mucosa, goblet cells) Lamina propria Muscularis mucosae
What is the biological mechanism behind Peutz-Jeghers syndrome?
<s>[INST] Answer the question truthfully, you are a medical professional. This is the question: What is the biological mechanism behind Peutz-Jeghers syndrome? [/INST] \n Polyps of Peutz-Jeghers syndrome are usually non-neoplastic hamartomas.  On microscopic histopathological analysis, polyps have the following characteristic findings: 
Frond-like polyp with all three components of mucosa: Muscosal epithelium (melanotic mucosa, goblet cells) Lamina propria Muscularis mucosae</s>