Localized AL amyloidosis of the colon: an unrecognized entity.

Virtually all patients who present with rectal bleeding and amyloid of the colon have evidence of systemic amyloidosis and require therapy. The small subset of patients with amyloidosis localized to the colon must be recognized and treatment avoided. We queried our file for patients who had amyloidosis of the colon but no evidence of systemic amyloidosis during long-term follow-up. We identified 3 patients who presented with rectal bleeding and who, on investigation, had primary amyloidosis of the colon but no evidence of systemic amyloidosis during a follow-up of 4.5 to 20 years. These patients had no evidence of a plasma cell dyscrasia and received no chemotherapy to prevent deposition of amyloid. It is important to recognize this rare subset and avoid treatment with alkylating agents or high-dose therapy followed by autologous stem cell transplantation. Alkylating agent therapy may be associated with myelodysplasia or acute leukemia. In addition, the cost, inconvenience, and morbidity of therapy are avoided by observation. Patients who present with rectal bleeding and a subsequent diagnosis of amyloidosis of the colon likely will be subjected to chemotherapy or transplantation. Such patients must be recognized and treatment avoided if there is no evidence of systemic amyloidosis because they remain stable for many years.