Clues to diagnosis for unusual mucosal pemphigus demonstrating undetectable anti-desmoglein 3 serum antibodies by routine tests.

Pemphigus is an autoimmune blistering disease caused by immunoglobulin (Ig)G autoantibodies against desmogleins (Dsg). In mucosal-dominant pemphigus vulgaris (PV), anti-Dsg3 antibodies play a critical role in acantholysis. We followed two mucosal-dominant PV cases who suffered from refractory oral mucosal erosions. In these cases, anti-Dsg3 serum antibodies were not detected by indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA). However, direct immunofluorescence showed the intercellular IgG deposition in the epidermis and histopathological findings revealed suprabasal acantholysis. In order to analyze the pathomechanisms in these cases, we first examined the Dsg3 expression patterns in lesional sites and compared them with those of typical mucosal-dominant PV cases. In typical PV cases, the alteration of Dsg3 distribution was observed in lesional sites by immunostaining. The aggregation of Dsg3, which is the characteristic change in PV mucosal lesions, was observed as the initial change prior to acantholysis. In our cases, a clustering of Dsg3 was observed at mucosal lesions, and the expression levels of Dsg3 in acantholytic lesions were decreased, as observed in typical mucosal-dominant PV cases. Although anti-Dsg3 serum antibodies could not be detected by routine tests, anti-Dsg3 serum antibodies were detected by Dsg3 ELISA using 10-times more concentrated sera (highly sensitive ELISA). Moreover, purified and concentrated PV IgG showed high pathogenicity when examined by dissociation assay. In conclusion, the detection of morphological changes in Dsg3 distribution and highly sensitive ELISA method could be useful for the early diagnosis of PV recurrence.

Increase of DC-LAMP+ mature dendritic cell subsets in dermatopathic lymphadenitis of mycosis fungoides.

BACKGROUND: Little is known about the immunological milieu of the skin-draining lymph nodes (LNs) in mycosis fungoides (MF). OBJECTIVES: We studied dendritic cell (DC) subsets in the dermatopathic lymphadenitis of MF patients. METHODS: We immunohistochemically examined DC subsets and their distribution in 16 LN samples from 14 patients with MF (N1 LN, eight patients; N2, four; and N3, four), and we compared them with non-metastatic sentinel LNs from eight patients with melanoma. RESULTS: The number of S-100 protein+ DCs was markedly increased in the LNs from the MF patients and the major component was DC-LAMP+ mature DCs in the outer and paracortex areas, where DC-SIGN+ immature DCs were relatively decreased in proportion. In contrast, DC-SIGN+ cells were relatively increased in proportion compared to DC-LAMP+ cells in the medulla. Although no significant difference was observed in the proportions of CD1a+ or Langerin+ DCs among the N1, N2, and N3 nodes, CD163+ M2-type macrophages were increased in number in the N2 and N3 nodes. CONCLUSIONS: Our observations indicate that mature DCs accumulate in the outer and paracortex areas in dermatopathic lymphadenitis and M2-type macrophages might increase in number during disease progression.