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Amyloidosis of the rectum mimicking collagenous colitis
R García-González1, F A Fernández, M F Garijo
1Department of Anatomical Pathology, Marqués de Valdecilla University Hospital, Medical Faculty, University of Cantabria, Santander, Spain.
Abstract:
Gastrointestinal involvement in cases of systemic amyloidosis is very common. In the colorectal mucosa, amyloid deposition is ordinarily seen around vessels or diffusely in the lamina propria. We report two cases in men aged 69 and 29 years, whose rectal biopsies revealed prominent subepithelial amyloid deposits mimicking collagenous colitis. The amyloid deposits were composed of AA protein. A review of the literature has yielded only one previously reported case. Pathologists should be aware of this deposition pattern of amyloid to prevent misdiagnosis. Our cases underline the importance of the routine use of histochemical stains for amyloid in all cases of colorectal biopsies showing histologic changes suggestive of collagenous colitis.
Insights
Systemic amyloidosis commonly affects the gastrointestinal tract. Researchers found AA protein amyloid deposits in the subepithelial colorectal layer, mimicking collagenous colitis, highlighting the need for specific stains in biopsies.
Area of Science:
- Gastroenterology
- Pathology
- Oncology
Background:
- Gastrointestinal involvement is common in systemic amyloidosis.
- Amyloid deposition typically occurs around vessels or in the lamina propria of the colorectal mucosa.
- AA protein amyloidosis is a specific type of amyloidosis.
Observation:
- Two male patients, aged 69 and 29, presented with rectal biopsies.
- Biopsies revealed prominent subepithelial amyloid deposits.
- These deposits mimicked the histological features of collagenous colitis.
Findings:
- The amyloid deposits were identified as AA protein.
- This subepithelial deposition pattern is rare, with only one prior case reported in the literature.
- The findings emphasize a distinct presentation of amyloidosis in colorectal biopsies.
Implications:
- Pathologists must be aware of this subepithelial amyloid deposition pattern to avoid misdiagnosis.
- Routine use of histochemical stains for amyloid is crucial in colorectal biopsies with changes suggestive of collagenous colitis.
- Accurate diagnosis of amyloidosis is essential for appropriate patient management.