Two cases of heavy chain disease associated with a different pathology

The heavy chain disease (HCD) is a rare B-cell lymphoproliferative disorder that may involve the three main immunoglobulin heavy chain isotypes, i.e. α, γ and μ, whose hallmark is the occurrence in serum of monoclonal heavy chains without associated light chains. HCD may have variable clinical presentations and different histopathologic features. We report two cases of HCD that, unlike most of the previously reported cases, were found in patients affected by a different pathology. The first patient, a 75 years old man, was affected by chronic lymphocytic leukemia and a γ-heavy chain without associated light chain was detected by immunofixation electrophoresis both in patient serum and urine. A monoclonal IgGλ was also detected in serum and a monoclonal free λ chain in urine. The second case refers to a 72 years old man affected by progressive multifocal leukoencephalopathy, showing γ-heavy chain incomplete fragments, both in serum and urine, and severe immunoglobulin deficiency.