Immunobullous dermatosis associated with Waldenström macroglobulinaemia treated with rituximab

Cutaneous manifestations of monoclonal gammopathy

Monoclonal gammopathy associated with dermatological manifestations are a well-recognized complication. These skin disorders can be associated with infiltration and proliferation of a malignant plasma cells or by a deposition of the monoclonal immunoglobulin in a nonmalignant monoclonal gammopathy. These disorders include POEMS syndrome, light chain amyloidosis, Schnitzler syndrome, scleromyxedema and TEMPI syndrome. This article provides a review of clinical manifestations, diagnostics criteria, natural evolution, pathogenesis, and treatment of these cutaneous manifestations.

Immunoglobulin M pemphigoid

BACKGROUND

Pemphigoid diseases are a heterogeneous group of autoimmune blistering disorders characterized by predominant deposition of immunoglobulin G or immunoglobulin A autoantibodies against structural proteins of the dermoepidermal junction (DEJ). Sole linear immunoglobulin M (IgM) deposits at the DEJ in pemphigoid diseases have been observed; however, IgM-specific target antigens have not been identified.

OBJECTIVE

Characterization of patients with IgM pemphigoid.

METHODS

Skin biopsy specimens and sera from IgM-positive patients were assessed using histopathology, direct and indirect immunofluorescence microscopy, enzyme-linked immunosorbent assays, immunoblotting, cryosection assay, complement fixation test, and internalization assays.

RESULTS

Tissue-bound linear IgM deposits along the DEJ and circulating IgM autoantibodies against type XVII collagen (Col17) were detected. These circulating IgM autoantibodies showed no complement activating or blister inducing capacity, but the ability of Col17 internalization ex vivo.

LIMITATIONS

Limited number of patients.

CONCLUSION

This study provides further evidence for the role of IgM autoantibodies in pemphigoid disease and highlights Col17 as a target antigen in IgM pemphigoid.

BP180 Is Critical in the Autoimmunity of Bullous Pemphigoid

Bullous pemphigoid (BP) is by far the most common autoimmune blistering dermatosis that mainly occurs in the elderly. The BP180 is a transmembrane glycoprotein, which is highly immunodominant in BP. The structure and location of BP180 indicate that it is a significant autoantigen and plays a key role in blister formation. Autoantibodies from BP patients react with BP180, which leads to its degradation and this has been regarded as the central event in BP pathogenesis. The consequent blister formation involves the activation of complement-dependent or -independent signals, as well as inflammatory pathways induced by BP180/anti-BP180 autoantibody interaction. As a multi-epitope molecule, BP180 can cause dermal-epidermal separation via combining each epitope with specific immunoglobulin, which also facilitates blister formation. In addition, some inflammatory factors can directly deplete BP180, thereby leading to fragility of the dermal-epidermal junction and blister formation. This review summarizes recent investigations on the role of BP180 in BP pathogenesis to determine the potential targets for the treatment of patients with BP.

Paraprotein deposits in the skin

Cutaneous manifestations secondary to paraprotein deposits in the skin include a group of different disorders that although rare, may be the first clinical manifestation of the underlying hematologic dyscrasia. In this article we review the clinical manifestations and histopathologic findings of the processes that result from specific deposition of the paraprotein in different structures of the skin. Paraneoplastic processes frequently associated with hematologic malignancies will not be covered in this review. Some of the disorders included here result from deposition of the intact paraprotein in the skin, whereas in other cases the lesions are due to deposition of modified paraproteins in the form of amyloid substance, cryoglobulins, or crystalglobulins. Cutaneous amyloidoma refers to nodular dermal deposits of amyloid derived from immunoglobulin light chains produced by local plasma cells in the absence of systemic amyloidosis. Dermatologists and dermatopathologists should be aware of the clinical and histopathologic features of these rare disorders because sometimes the cutaneous lesions are the first sign of an underlying silent hematologic malignancy with paraproteinemia.

Possible paraneoplastic syndrome case of bullous pemphigoid with immunoglobulin G anti-BP180 C-terminal domain antibodies associated with psoriasis and primary macroglobulinemia

A 61-year-old Japanese man developed bullous skin lesions during topical therapy for psoriasis vulgaris. Physical examination demonstrated numerous tense bullae and scaly erythemas on the trunk and extremities. Histopathology of the skin biopsy demonstrated subepidermal bullae and lymphocytic infiltration with eosinophils in the dermis. Direct immunofluorescence revealed linear deposits of immunoglobulin (Ig)G, IgA and C3 along the basement membrane zone. Indirect immunofluorescence of 1 mol/L NaCl-split skin showed IgG reactivity with both epidermal and the dermal sides. IgM reactivity with both the epidermal and dermal sides was also detected. Enzyme-linked immunosorbent assays showed negative results for both BP180 and BP230. Immunoelectrophoresis of serum and bone marrow aspiration revealed underlying primary macroglobulinemia with M-proteinemia of IgM-κ type. Immunoblot analysis revealed IgG, but not IgM, antibodies to recombinant protein of BP180 C-terminal domain. We diagnosed the present case as bullous pemphigoid with IgG anti-BP180 C-terminal domain autoantibodies associated with primary macroglobulinemia and psoriasis vulgaris. Systemic administration of prednisolone 30 mg/day resulted in dramatic improvement of both bullous and psoriatic skin lesions. When the bullous and psoriatic lesions relapsed, DRC chemotherapy (dexamethasone, rituximab and cyclophosphamide) for macroglobulinemia was performed. Then, the psoriatic lesions improved and the bullous lesions disappeared. We suggested that the present case may be paraneoplastic syndrome of bullous pemphigoid associated with primary macroglobulinemia and psoriasis vulgaris.