Biological Significance of the Association Between Cutaneous Al-amyloidoma and Sjögren Syndrome.

To the Editor: We read with great interest the case report of cutaneous amyloid L (AL)-amyloidoma by Ueberdiek et al,1 in which the authors emphasize the close relationship between AL-amyloidoma of the skin and primary cutaneous marginal zone lymphoma (pcMZL). We hereby report a case of cutaneous ALamyloidoma occurring in the setting of long-standing Sjögren syndrome (SjS), expanding on the observations by Ueberdiek et al.1 We believe that the significant association between ALamyloidoma of the skin and SjS further supports the conclusions by Ueberdiek et al1 regarding the biological link between cutaneous AL-amyloidoma and pcMZL. A 67-year-old woman with a 15year history of SjS presented with an erythematous, waxy plaque of 4.5 cm in diameter located on the right lumbar region (Fig. 1). According to the patient, the lesion was asymptomatic and had rapidly developed in the previous 2 months. SjS was stably controlled under immunosuppressive treatment with hydroxychloroquine. Hematologic laboratory investigations of serum and urine (including protein electrophoresis, immunoglobulins, and free light chains) were unremarkable; total-body computed tomography failed to reveal any significant abnormality. A punch biopsy was obtained from the center of the plaque for histologic evaluation. Histology showed extensive deposition of eosinophilic amorphous extracellular material throughout the dermis, with involvement of several smalland medium-sized vessels, and compression/replacement of normal skin structures (Figs. 2A, B, and C); positivity for Congo red stain with apple-green birefringence under polarizing light confirmed the amyloid nature of the eosinophilic deposits (Fig. 2D). An accompanying, sparse lymphoplasmacytic infiltrate with perivascular distribution could be also observed; the scant plasma cell population appeared monoclonal with lambda chain restriction by in situ hybridization for immunoglobulin light chains (Figs. 2E and F). On clinicopathological correlation, a diagnosis of cutaneous ALamyloidoma was made; the lesion was completely excised. No recurrence has been observed after 18-month followup. Cutaneous amyloidoma is an indolent condition characterized by a localized plaque/tumor which consists of dermal and/or subcutaneous amyloid deposits (in most cases of AL type) in the absence of systemic amyloidosis.2–4 As such, cutaneous amyloidoma may be regarded as a clinicopathological presentation of primary cutaneous nodular amyloidosis.2 Clinically, cutaneous ALamyloidoma typically presents as a single plaque/nodule with a waxy tan appearance, preferentially arising in elderly individuals.2,3 Histologically, dense deposits of amyloid are observed in the dermis/subcutis, in association with a sparse perivascular infiltrate consisting of lymphocytes and plasma cells.2–4 Absence of systemic amyloidosis, multiple myeloma, and other light chain–related diseases is mandatory to make a diagnosis of cutaneous ALamyloidoma.2 It has been controversial whether cutaneous AL-amyloidoma should be considered as a localized form of amyloidosis, a localized plasma cell dyscrasia with amyloid deposition, a “smoldering” type of extramedullary plasma cell neoplasm, or a member of the family of extranodal MZL.2–5 Although older reports failed to consistently detect a monotypic light chain restriction in plasma cells of cutaneous AL-amyloidoma, recent studies have confirmed that the latter are always monotypic, supporting their clonal, neoplastic nature.2 We agree with the view of Ueberdiek et al1 that cutaneous ALamyloidoma should be regarded as a clinicopathological variant of pcMZL, as already suggested by the fact that in sporadic patients cutaneous