NODULAR AMYLOID (Localized Cutaneous)

Nodular Amyloid (NA) or Primary Localized Cutaneous Nodular Amyloidosis (PLCNA) is the rarest form of cutaneous amyloidosis with the amyloid depositing in the dermis, subcutis, and blood vessel walls.

• Firm, waxy, translucent papules.
  
• Progression from localized nodular amyloid to systemic amyloidosis has been estimated at 7%.
• Plasma cells within the skin secrete immunoglobulin light chains containing fibrillogenic amino acids. These are phagocytosed by macrophages, digested which results in insoluble amyloid fibrils.
• Both kappa and lambda light chain amino acid homologies have been found.
• Monoclonality of the infiltrating cells has been detected by both Southern blot analysis and PCR.

Single or multiple waxy plaques or nodules in an older adult is characteristic. Cutaneous nodules representing deposits of amyloid may occur alone or in association with systemic amyloid. For this webpage, the term nodular amyloid refers to cutaneous lesions in the absence of systemic disease. The consistency of the lesion may be rubbery, firm, waxlike or anetodermic. Referral to a hematologist/oncologist to exclude multiple myeloma is in order. 14 cases of nodular amyloidosis of the penis have been reported.

Prognosis

In one study, the progression to systemic amyloidosis was 7%.

Workup

Serum protein electrophoresis (SPEP), urine protein electrophoresis (UPEP), immunofixation electrophoresis (IFE), antinuclear antibodies (ANAs) are indicated.

RegionalDerm

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