Involved tissues usually include mucosa-associated lymphoid tissues and evidence a histology of lymphoplasmacytoid infiltrates accompanied by large numbers of plasma cells and small lymphocytes. The plasma cells therein express the monoclonal α chain and therefore are clonal in nature and the sole or contributing producer of the α chain myeloma protein. Some 57% to 66% of patients present with disseminated lymphoma, 17% to 36% of patients present with a localized lymphoma, and 9% to 17% of patients lack any evidence of a lymphoplasmacytic neoplasm. A majority of the latter patients have an autoimmune disease or a chronic infection which may be responsible for, or contribute to, production of the α heavy chain. Studies indicated that a sub-set particularly of the digestive form of heavy chain disease is caused by infection. This is based on findings that the majority of α heavy chain disease patients are in the lower economic class living under unsanitary conditions, that gastrointestinal bacterial and parasitic infections have been documented in many of these patients, and that long-term (>6 months) appropriately selected antibiotic therapy has improved the condition in 33% to 71% of patients who are at an early stage of the disease and documented to be infected. However, these patients frequently relapse. Patients resistant to antibiotic trials have been treated with multiple drug chemotherapy to obtain complete remission rates of 64% and an overall 5 year survival of 67%.
Reflecting the widespread systemic nature of the disease, patient median survival is only 8 months dating from the time of diagnosis. Treatment commonly improves this poor survival. In a Mayo Clinic study, for example, AL amyloidosis assigned stage 1, 2, 3, or 4 based on the presence of 0, 1, 2, or 3 prognostic signs (high blood levels of [cardiac troponin T]), blood levels of a marker for congestive heart failure (viz., NT-ProBNP), or free light chain ratios) had median survivals of 94.1, 40.3, 14, and 5.8 months respectively. Additional factors indicating a worse prognosis include the involvement of multiple organs, ≥ 10% bone marrow plasma cells, presence of a translocation between chromosomes 11 and 14 [i.e. t(11;14)], and chromosomal trisomy. AH Amyloidosis
AH and AHL amyloidosis are extremely rare forms of systemic amyloidosis in which the amyloid deposit is a free heavy chain (AH amyloidosis) or a free heavy chain plus free light chain (AHL amyloidosis). Case reports have detected amyloid deposits containing a free γ, α, or μ heavy chain (or portions of one of these chains) accompanied in many cases by a free κ or λ light chain in primarily in the kidney but also the spleen and other tissues. AH plus AHL amyloidosis cases are ~17-fold less common than AL amyloidosis cases. The disease often presents late in its course with signs and/or symptoms of kidney failure such as those associated with the nephrotic syndrome and is therefore treated as a malignant condition.