Cytopathology of alpha chain disease involving the central nervous system and pleura.

Alpha chain disease, a lymphomatous disorder characterized by the synthesis and secretion of an abnormal IgA immunoglobulin devoid of light chains, involves mainly the gastrointestinal tract. This paper presents the cytologic and histologic findings in two cases of alpha chain disease involving the central nervous system and pleura. Most of the cell populations in the cerebrospinal fluid (CSF) and pleural fluid resembled immature plasma cells (immunoblasts); many of these cells were degenerated, with well-preserved plasma cells seen more rarely. While the definitive diagnosis of alpha chain disease depends on immunochemical analysis of serum proteins, cytology can play a role by the identification of malignant cells in CSF and pleural fluid specimens. A positive staining of such cells by the methyl green pyronin reaction may permit the correct diagnosis to be suggested.