Surgical Pathology Criteria

Hereditary Mixed Polyposis Syndrome

Differential Diagnosis

Juvenile Polyposis Hereditary Mixed Polyposis
Most cases present in childhood Mean age at presentation 41 years
Usually 50-200 polyps Usually 1-15 polyps, rarely >50
Adenomas infrequent Adenomas common
The gastrointestinal polyps in some cases are indistinguishable

 

Hereditary Mixed Polyposis Familial Adenomatous Polyposis
Mixtures of adenomatous and juvenile type polyps Colorectal polyps are all adenomatous
Polyps may have mixed adenomatous and juvenile features Colorectal polyps lack juvenile features
No extra-colorectal associated lesions May be associated with duodenal adenomas, gastric fundic gland polyps, desmoid tumors and other extra-gi disorders
No APC mutation Mutation in APC gene

 

Cowden Disease Hereditary Mixed Polyposis Syndrome
Most cases present in childhood Mean age at presentation 41 years
Usually 50-200 polyps Usually 1-15 polyps, rarely >50
Adenomas infrequent Adenomas common
Most have facial mucocutaneous lesions, see description No associated mucocutaneous lesions
Frequent breast hamartomas and carcinomas No association with breast hamartomas or carcinomas
Frequent thyroid carcinomas No association with thyroid carcinomas
The polyps in some cases are indistinguishable

 

Cronkhite-Canada Syndrome Hereditary Mixed Polyposis Syndrome
Usually >50 polyps Usually 1-15 polyps, rarely >50
Adenomas infrequent (sporadic adenomas may occur) Adenomas common
Hair, nail, skin pigmentation changes present No associated extra-GI lesions
Not familial Autosomal dominant
The polyps in some cases are indistinguishable

 

Serrated Polyposis (Hyperplastic Polyposis) Hereditary Mixed Polyposis
Adenomatous cytologic features infrequent, focal at most Most polyps are adenomatous, either pure or mixed
Most polyps are sessile Most are polypoid, regardless of  histology
Glands are vertically arranged and not complex Frequently shows features of juvenile polyps: prominent stroma, cystic dilation

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