Track: Case Reports

Abstract:

Herein we present a case of a 75-year-old male with a remote history of sarcoma of unknown subtype of the right shoulder who presented with two firm, nontender subcutaneous right supraclavicular nodules measuring 1.0 cm and 0.7 cm. Histopathologic examination revealed a spindle cell dermal proliferation with eosinophilic cytoplasm arranged in a storiform pattern infiltrating adipose lobules, producing a honeycomb appearance. Surrounding the spindle cells was abundant pale, amorphous eosinophilic extracellular material. The lesional cells demonstrated strong and diffusion immunochemical reactivity with CD34 and genomic profiling identified a COL1A1::PDGFB fusion, a characteristic fusion of dermatofibrosarcoma protuberans (DFSP). Additionally, the extracellular amorphous material stained with crystal violet and Congo red staining confirmed amyloid deposits. Liquid chromatography-tandem mass spectrometry detected a peptide profile consistent with transthyretin (ATTR)-type amyloidosis. These findings were consistent with a unique phenomenon of DFSP arising in the background of age-related amyloidosis. DFSP is one of the most common cutaneous sarcomas typically affecting the extremities or trunk of young to middle-aged adults. Although associations with chronic lymphedema, surgical scars, and vascular malformations have been described, to our knowledge, this is the first reported case of DFSP arising in the context of age-related amyloidosis. We aim to raise awareness of this potentially underrecognized association and to prompt further investigation into its clinicopathologic significance.