Amyloid Disease

Abstract

The pathogenesis of amyloid disease is poorly understood; yet its clinical and pathological manifestations were first observed by Rokitansky (9) and were subsequently described in detail by Virchow (13), in 1858. Since its recognition as a disease entity, sporadic case reports have appeared in the world literature, but little has been written from the radiologist's point of view. We have sought therefore to discover and summarize the roentgen aspects of the condition. Amyloid is a starch-like material of waxy appearance, which stains readily with iodine. Its exact chemical nature is not well understood, but it is regarded as a complex substance containing protein and polysaccharides. There are two types of amyloid disease, primary and secondary. Primary amyloidosis is relatively uncommon, approximately 70 cases having been reported. The amyloid is usually deposited in the lungs, heart, and blood vessels throughout the body; it is found less frequently in the spleen and gastrointestinal tract. Primary amyloidosis is not associated with chronic sepsis nor with any other known etiologic factor. The amyloid does not always absorb the usual stains, such as Congo red, iodine, or methyl violet. A solitary tumor-like deposit may, on rare occasions, be found in a particular organ; the nasal septum, thyroid, tongue, and larynx are frequent sites. Secondary amyloidosis, the more common form of the disease, is usually associated with long standing infections and tissue-destroying processes. It is often found with rheumatoid arthritis, bronchiectasis, tuberculosis, and malignant tumors. In contrast to the primary form, the secondary amyloid absorbs stains well. The deposits occur almost always in the liver, spleen, kidneys, and adrenal glands. A particular type of amyloid disease associated with multiple myeloma usually follows the distribution pattern and staining reaction commonly seen in primary amyloidosis. From a clinical standpoint, the signs and symptoms of amyloidosis vary, depending upon the system primarily involved. When there is considerable infiltration of the kidneys, the findings may be similar to those of the nephrotic syndrome. If the liver or spleen is significantly involved, there may be no particular symptoms but the organs may be palpable. Involvement of the stomach may cause hematemesis, epigastric distress, and pyloric obstruction, or the patient may be asymptomatic. When the small bowel is infiltrated, chronic diarrhea is a frequent manifestation. Amyloid deposition in the heart may produce no clinical evidence of its presence, except for certain electrocardiographic changes, until late in the process, when decompensation becomes intractable. Involvement of the lungs rarely gives rise to symptoms until the infiltration becomes massive, when progressive shortness of breath develops.