Background: Cutaneous plasmacytosis is a rare disease characterized by peculiar multiple eruptions and hypergammaglobulinemia. More than 40 cases have been reported, mainly in Japan, although information concerning the disorder was limited to individual case reports. Objective and Methods: To clarify the clinicopathological and laboratory features, we reviewed 41 cases. Results: All patients were Japanese and the male-to-female ratio was 1:0.6. The onset ages ranged from 20 to 62 years, with a mean and median of 37 and 37 years. A superficial lymphadenopathy was detected in 58% (22/38), and polyclonal hypergammaglobulinemia was found in 93% (38/41). No cases were associated with any apparent underlying diseases. The course was chronic without spontaneous remission. Four patients died, 3 of whom succumbed to leukemia, respiratory failure or renal failure, respectively. Conclusion: The results suggest that the condition appears to be a variant of reactive plasmacytic disorders of unknown origin.