Multiple myeloma
Skin lesions are uncommon and occur late in the course of disease.
• Plasma cell tumours: erythematous/purplish nodules—direct extension into the skin
from an underlying bone disease or metastatic disease.
• Neutrophilic dermatoses, including subcorneal pustular dermatosis, erythema elevatum
diutinum, urticarial vasculitis, Sweet syndrome, PG (IgA gammopathy). Also urticarial-
like neutrophilic dermatosis reported— asymptomatic urticarial-like erythematous
plaques, commonly affecting the trunk. Persists for days and may resolve with
hyperpigmentation.
• Amyloidosis may have cutaneous manifestations.
• Type 1 cryoglobulinaemia: cold sensitivity, mottling, cyanosis, purpura, blisters, ulcers
(occlusive vasculopathy).
• POEMS syndrome—rare.
• Follicular spicules, particularly on the nose. Also scalp and neck.
• Acquired cutis laxa—granuloma annulare-like plaques clinically.
• Papular mucinosis.
Waldenström macroglobulinaemia
• Epistaxis and oral mucosal bleeding.
• Cutaneous macroglobulinosis—flesh-coloured papules on extensors.
• evidence of type 1 cryoglobulinaemia as in myeloma (IgG or IgM).
• May be preceded by Schnitzler syndrome (IgM).
IgG4-related disease
• Characterized by raised levels of IgG4, tissue infiltration of IgG4- positive plasma cells,
and presence of fibrosis.
• Affects multiple organs, including the pancreas, bile duct, lacrimal and salivary glands,
thyroid.
• Skin lesions reported—mainly head and neck.
• Cutaneous disease responds to oral corticosteroids.
• IgG4 levels do not correlate with disease activity.
