Localized Cutaneous Nodular Amyloidosis: A Specific Cutaneous Manifestation of Sjögren's Syndrome

Abstract

Primary localized cutaneous nodular amyloidosis (PLCNA) is a rare condition attributed to plasma cell proliferation and the deposition of immunoglobulin light chains in the skin without association with systemic amyloidosis or hematological dyscrasias. It is not uncommon for patients diagnosed with PLCNA to also suffer from other auto-immune connective tissue diseases, with Sjögren's syndrome (SjS) showing the strongest association. This article provides a literature review and descriptive analysis to better understand the unique relationship between these two entities. To date, 34 patients with PLCNA and SjS have been reported in a total of 26 articles. The co-existence of PLCNA and SjS has been reported, especially in female patients in their seventh decade of life with nodular lesions on the trunk and/or lower extremities. Acral and facial localization, which is a typical localization of PLCNA in the absence of SjS, seems to be much more unusual in patients with associated SjS.

Keywords: Sjögren’s Syndrome; auto-immune connective tissue disorders; localized cutaneous nodular amyloidosis; plasma cells.

Figure 1

Patient with primary localized cutaneous nodular amyloidosis (PLCNA). Partially ulcerated yellowish nodule on the anterior aspect of the left leg.

Figure 2

Schematic representation of the etiopathogenesis of Sjögren’s Syndrome (SjS) and the development of primary localized cutaneous nodular amyloidosis (PLCNA). ① The epithelial cells of the salivary gland itself and acquired immunity both play a key role in the etiopathogenesis of a patient with SjS. Epithelial cells act as initiators of the immune response by expressing ribonucleoproteins on their surface, producing cytokines, and interacting with T lymphocytes. Tissue infiltration and progressive destruction by T and B cells occur, with the latter being the fundamental cells in the etiopathogenesis and producing cytokines, such as interleukin-6 (IL-6) and interleukin-10 (IL-10). There is also an increase in serum B cell activating factor (BAFF) levels. ②, ③ B cell hyperactivity leads to the deposition of light chain-producing plasma cells in the skin. ④ The deposition of light chains leads to the formation of AL amyloid protein. The cutaneous “amyloidoma” gives rise to the characteristic plaques and nodules with a tendency to become chronic and ulcerated.

Figure 3

Pie chart. Reported locations of primary localized cutaneous nodular amyloidosis (PLCNA) in the 34 patients described to date with Sjögren Syndrome (SjS).