Immunohistochemical study of immunoglobulin light chains and inflammatory cells in a patient with localized primary cutaneous nodular amyloidosis

Primary localized cutaneous lichen myxedematosus with light chain-restricted plasma cells: A distinct variant of the localized form of lichen myxedematosus

Lichen myxedematosus (LM) is a chronic cutaneous mucinosis that can present as a localized skin lesion or as a generalized systemic disease termed scleromyxedema. The differential diagnosis is determined by a combination of clinical presentation, serological studies, and histopathological examination. Currently, well-established and accepted histopathological features to distinguish localized LM from scleromyxedema have not been elucidated. Our recent publication, together with a retrospective literature review, suggests that the presence of groups of light chain-restricted plasma cells represents a distinct histopathological clue for the diagnosis of localized LM. In this report, we provide two additional cases of localized LM with lambda light chain-restricted plasma cells, together with clinical and histopathological findings that are similar to our previous publication. These cases support our theory that the light chain-restricted plasmacytic microenvironment is primarily attributed to the pathogenesis of localized LM. Therefore, we consider these cases to constitute a clinically and pathologically new variant of localized LM and name it primary localized cutaneous LM with light chain-restricted plasma cells.

Primary Localized Cutaneous Nodular Amyloidosis and Limited Cutaneous Systemic Sclerosis: Additional Cases with Dermatoscopic and Histopathological Correlation of Amyloid Deposition

Primary localized cutaneous nodular amyloidosis (PLCNA) is a rare condition due to the plasma cell proliferation and skin deposition of immunoglobulin light chains, without systemic amyloidosis or hematological dyscrasias. The association with autoimmune connective tissue diseases has been reported, especially with Sjogren’s syndrome, and in a few cases with systemic sclerosis. Herein, we describe three cases of PLCNA occurring in women with a diagnosis of limited cutaneous systemic sclerosis and review the literature on the topic to highlight a stereotypical presentation. Moreover, we support the usefulness of dermoscopy, characterized by a yellow–orange waxy pattern surrounded by telangiectasias, for a rapid and non-invasive diagnostic assessment. Thus, when asymptomatic nodules occur on lower limbs of women affected with limited systemic sclerosis, and dermoscopy identifies yellow–orange blotches, a diagnosis of PLCNA can be considered and further confirmed by histopathology. Monitoring for systemic amyloidosis development is advisable, although the risk of progression is considered very low.