Autopsy reports are different everywhere. A lot of times they are long because there is a lot of protocol and general descriptions which, frankly, don't contribute much to the diagnosis but are there for completeness' sake.
Standard autopsy reports will generally include:
A general, gross description (measurements, weights of organs, descriptions of scars and wounds and medical equipment, pathologic findings like tumors or fluid collections). This is usually the bulk of the report and is organized in sections - general & external exam, thoracic cavity, abdominal cavity, brain, etc.
Microscopic description: What is seen on the slides. Generally this is pretty short, less than a page.
Final diagnosis: Also usually short, often only a couple of lines depending on how many findings there are. Some things that are small and insignificant are often not mentioned.
Sometimes there is a brief clinical history included.
Depending on the institution, there may be a statement relating findings to cause of death (in narrative form).
If you have concerns, I would take it to your doctor or your mother's doctor. Contact the path department where it was issued from if you have specific concerns. Many autopsies are also limited by the family (family requests no brain exam, for example) and are thus shorter. Reports at my institution are generally about 10 pages, but like I said about 8 of this is the gross description.
