Plasmacytosis is a condition in which there is an unusually large proportion of plasma cells in tissues, exudates, or blood.: 743  Plasmacytosis may be divided into two types—cutaneous and systemic—both of which have identical skin findings.: 743  Patients with plasmacytosis have been predominantly found to have lung infections (pneumonia, tuberculosis, abscess) whereas multiple myeloma is rarely found..