Characterization of Cutaneous Plasmacytosis at Different Disease Stages

Abstract

Background/Aims: Cutaneous plasmacytosis is rare and still not well understood. A retrospective study was made of 9 Chinese patients with 1- to 15-year histories of biopsy-proven cutaneous plasmacytosis diagnosed between 2003 and 2015. Methods: Patient records and archival photographs helped establish the pattern and duration of skin lesions, and skin biopsy specimens provided additional data. Results: The mean age at diagnosis was 46.4 years. Two patients had lesions within 1 year of developing the disease, and 4 had lesions lasting longer than 5 years. One patient had lymphadenopathy of the neck that was later determined to be Castleman disease. Three patients had elevated IgG4 levels; only 2 had increased IgG4+ cells in skin tissues. Flexural accentuation was prominent. Four patients had elevated IgG levels, and 1, with an IgG level >5,000 mg/dL, developed systemic plasmacytosis (later confirmed as Castleman disease). The level of IgG4 subclass was related to disease duration, whereas IgG4+ plasma cells in tissues seemed irrelevant. Conclusion: Routine laboratory tests, especially measurement of IgG4 levels, may be useful for following patients with cutaneous plasmacytosis. Because of the retrospective nature of our study, we could only evaluate the results of a single IgG4 test for each patient, but the results pointed to cutaneous plasmacytosis in all 9 patients, who had different stages of the disease. Serial skin biopsies may also be helpful for gauging disease progress. Although IgG4-related disease was not established in any of these patients, long-term follow-up is warranted for all patients.

Skin-Associated B Cells in Health and Inflammation

“…The isotype (i.e., subclasses of IgG, IgA, IgM, and/or IgE) produced by plasma cells in lesional skin varies depending on the skin site and type of inflammation (for examples, see Refs. [32][33][34]. Ig-secreting cell accumulation in inflamed skin leads to higher Ig titers in lymph draining the skin site, reflecting an increase in tissue titers (8).…”

“…Recently, B cells are increasingly recognized as an important part of the infiltrating immune compartment in autoimmune and inflammatory skin diseases. B cell numbers are elevated in lesional skin relative to control skin specimens in a number of inflammatory diseases, including, but not limited to, psoriasis (47), pemphigus (18), lupus profundus (19,20), systemic sclerosis (scleroderma) (48), discoid lupus erythematosus (49,50), Sjögren's syndrome (51), IgG4related skin diseases (33,34), atopic dermatitis (52), and allergic contact dermatitis (53). Although an increase in skininfiltrating B cells already suggested a role for B cells in cutaneous inflammation, the therapeutic success of systemic B cell depletion with rituximab confirmed a pathogenic role for B cells in a number of these diseases (54)(55)(56).…”

Plasmacytic cutaneous pathology: A review

“…Cutaneous plasmacytosis mainly affects adult Asian males and is characterized clinically by widespread non‐scaly, erythematous/brown plaques on the trunk and head/neck. Microscopically the lesions display mature, polytypic, plasma cell‐rich cutaneous infiltrates in perivascular, interstitial and perineural distributions.…”

“…Although etiologic factors often remain elusive, clarification of disease mechanisms has emerged. For example, the causes of systemic plasmacytosis, multicentric Castleman's disease and IgG4‐related disease are unknown but many of the relevant inflammatory pathways have been identified . This has helped to hone therapeutic strategies.…”

“…A clear role for the abnormal paraprotein in the pathogenesis of these disorders has not been eluci- disease are unknown but many of the relevant inflammatory pathways have been identified. 2,7,8 This has helped to hone therapeutic strategies.…”