Primary Cutaneous Nodular Amyloidosis: A Rare Disease.

A 40-year-old male presented with a 6-month history of a gradually progressing, painless, firm, 10 × 8 mm erythematous nodule on his nose [Figure 1]. Skin biopsy showed nodular deposition of eosinophilic, acellular, amyloid material in the entire dermis, which was surrounded by focal plasma cell infiltrate [Figure 2]. This material was congophilic [Figure 3] and demonstrated kappa light chain restriction on immunohistochemistry [Figure 4]. Systemic amyloidosis was ruled out by laboratory investigations, and thus, a diagnosis of primary nodular cutaneous amyloidosis, immunoglobulin light chain (AL) type was made.

Figure 1

Firm, erythematous-yellow, 10 × 8 mm nodule on the nose

Figure 2

Skin biopsy showing deposition of pale, pink, eosinophilic amyloid material in the dermis (H and E, ×200)

Figure 3

The amyloid material shows congophilia (Congo red, ×200)

Figure 4

The amyloid shows kappa light chain positivity (immunohistochemistry, ×200)

Cutaneous amyloidosis comprises three varieties – macular, lichenoid, or the rare nodular form. The amyloid protein in the nodular form is of AL type, which consists of monoclonal immunoglobulin light chain.[12] It is thought that AL amyloid in the cutaneous nodular form is produced by local plasma cells infiltrating the dermis. Some authors have reported a 7–50% risk of progression from localized nodular cutaneous amyloidosis to systemic forms on long-term follow-up.[34] This patient did not reveal any clinical or laboratory manifestation of multiple myeloma during a 2-year follow-up. Consequently, it is important to exclude underlying systemic disease at presentation in such patients and long-term follow up is recommended.

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