Acta Dermato-Venereologica 97-4 | Page 29

SHORT COMMUNICATION Linear IgA Bullous Dermatosis Associated with Immunoglobulin Light-chain Amyloidosis Yasuyuki YAMAGUCHI 1 , Hideyuki UJIIE 1 *, Hiroyuki OHIGASHI 2 , Hiroaki IWATA 1 , Ken MURAMATSU 1 , Tomoyuki ENDOU 2 , Takanori TESHIMA 2 and Hiroshi SHIMIZU 1 Departments of 1 Dermatology and 2 Hematology, Hokkaido University Graduate School of Medicine, North 15 West 7, Kita-ku, Sapporo 060- 8638, Japan. *E-mail: [email protected] Accepted Nov 23, 2016; Epub ahead of print Nov 24, 2016 Linear IgA bullous dermatosis (LABD) is a rare subepi- dermal autoimmune blistering disorder in which most cases have IgA autoantibodies to the 120-kDa and/or 97- kDa shed ectodomains of type XVII collagen (COL17, BP180) at the basement membrane zone (BMZ) (1). The aetiology of LABD remains largely unclear, although associations with drugs, infections and malignancies have been reported (2). Immunoglobulin light-chain (AL) amyloidosis is caused by the deposition, in tissue, of misfolded light-chains, which are produced by clonal plasma cells, resulting in multi-organ dysfunction (3). AL amyloidosis often develops against a background of monoclonal gammopathy. It has been reported that some monoclonal antibodies from patients with monoclonal gammopathy possess antigen-binding activity directed to autoantigens (4). We report here a case of LABD associated with IgA AL amyloidosis. To the best of our knowledge, this is the first case of LABD associated with systemic AL amyloidosis. 528 CASE REPORT A 73-year-old Japanese man was referred to our outpatient clinic with a 1-week history of vesicles on the extremities. He had also had severe proteinuria and hypertension for 6 months and had received a thorough examination at the department of haematology. He had taken no additional medications for one year before the onset of bullous lesions. Physical examination revealed numerous tense vesicles less than 5 mm in diameter surrounded by itchy erythema on the left elbow and the ankles and lower back (Fig. 1a). A biopsy specimen obtained from a vesicle on the left elbow showed a subepidermal blister, which contained neutrophils and eosinophils (Fig. 1b). Direct immu- nofluorescence (DIF) demonstrated linear deposits of IgA (Fig. 1c), but not of IgG or IgM, at the BMZ. Further investigation revealed that those IgA autoantibodies possess the lambda-light chain (Fig. 1d), but not the kappa-light chain (Fig. 1e). Indirect immunofluorescence (IIF) was positive for IgA at the BMZ up to ×64 dilutions. 1M NaCl-split skin IIF was positive for IgA on the epidermal side (Fig. 1f). Chemiluminescent enzyme immunoassay of COL17 NC16A was negative for IgG. From these findings, a diagnosis of LABD associated with IgA-lambda autoantibodies was made. Fig. 1. Clinical and analytical characteristics of the patient. (a) Tense vesicles surrounded by itchy erythema on the left elbow. (b) Biopsy specimen from a vesicle on the left elbow shows subepidermal blisters containing numerous eosinophils and neutrophils (haematoxylin and eosin staining, original magnification ×100). (c–e) Direct immunofluorescence (DIF) reveals linear deposits of (c) IgA and (d) lambda light chain, but not (e) kappa light chain at the BMZ of lesional skin. (f) 1M NaCl-split skin IIF is positive for IgA on the epidermal side. (g) Immunofixation reveals monoclonal paraprotein IgA-lambda in the serum. (h) Mesangial deposits of amyloid on the renal specimen (direct fast scarlet (DFS) staining, original magnification ×200). Deposits of amyloid on: (i) submucosa of the rectum and (j) the lamina propria and submucosa of the sigmoid colon (DFS staining, original magnification ×40). doi: 10.2340/00015555-2590 Acta Derm Venereol 2017; 97: 528–529 This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2017 Acta Dermato-Venereologica.