Ashlee Hedrick^1,2, Nirija Ranjit Anderson ^2,3  Eloise House ⁴ Mimi Yue ^1,2,4
1Department of Haematology, Mater Hospital, South Brisbane, QLD, Australia
²Faculty of Medicine, University of Queensland, Australia
³Department of Haematology, Princess Alexandra Hospital, Brisbane, QLD. Australia
⁴Mater Pathology, South Brisbane, QLD, Australia

Introduction
Amyloid fibrils are misfolded proteins that become insoluble and precipitate in extracellular spaces (1). Insulin amyloid (AIns) has been previously described as a skin complication of subcutaneous insulin therapy (2). Here we describe a case of AIns amyloid presenting as adenopathy in a patient with Rabsan-Mendenhall Syndrome; a rare endocrine disorder characterised by severe insulin resistance (3).

Case Report
A 24-year-old female with a known history of Rabsan-Mendenhall syndrome presented with 10kg of weight loss. Her daily insulin requirements were over 4000U per day. CT demonstrated bilateral prominent inguinal lymphadenopathy with soft tissue thickening in upper thigh and lower abdomen. Ultrasound guided core-biopsy of the inguinal node revealed amorphic material positive on Congo Red staining. The deposits were positive for insulin using immunohistochemistry. Mass spectrometry showed a peptide profile consistent with AIns amyloid. There were no other affected organs.

Discussion
AIns amyloid is a rare disorder with literature limited to case reports. It is difficult to determine if this case was localised subcutaneous amyloidosis that drained into the inguinal nodes or truly systemic amyloidosis.

Conclusion
To our knowledge, this is the first case of AIns amyloid in a patient with Rabsan-Mendenhall Syndrome.

References
Buxbaum et al, 2022. Amyloid.
Qafary et al, 2022. Progress in Biophysics and Molecular Biology.
Gong et al, 2024. Journal of the Endocrine Society.

Statement of Originality
This case was diagnosed by The Mater Hospital Brisbane.