A Case of POEMS Syndrome and Associated Endocrinopathies: Hypogonadism and Subclinical Hypothyroidism

Case Report A Case of POEMS Syndrome and Associated Endocrinopathies: Hypogonadism and Subclinical Hypothyroidism Kyle L. Yamamoto 1,2 and Samuel T. Olatunbosun 1,2,* 1 Endocrinology Section, Sacramento Veterans Affairs Medical Center, Mather, CA 95655, USA 2 Division of Diabetes and Metabolism Division, Department of Internal Medicine, University of California Davis, Davis, CA 95616, USA * Correspondence: [email protected] Received: 7 February 2025; Accepted: 19 February 2025; Published: 8 April 2025 Abstract: POEMS is a rare paraneoplastic syndrome characterized by polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes. Castleman disease (angiofollicular lymph node hyperplasia) and elevation of serum vascular endothelial growth factor (VEGF) are associated features as well. Pathogenesis of POEMS syndrome is still unclear, although a loss of balance between proinflammatory and anti-inflammatory cytokines is considered the underlying pathophysiology. Hypogonadism is the most common endocrinopathy encountered in POEMS syndrome. We report the case of a 45-year-old man with history of hypogonadism who developed Castleman disease. He was eventually diagnosed with POEMS syndrome upon developing polyneuropathy, his VEGF levels were elevated, and additionally, he was found to have subclinical hypothyroidism. Clinical and biochemical response to therapy and the course of his disease are presented. With treatment and normalization of his VEGF levels, his repeat thyroid function testing showed a decrease in his thyroid stimulating hormone levels to normal range. His hypogonadism continued to require testosterone replacement therapy. A potential role of cytokines and angiogenic factors in the development of the disease including the endocrinopathy component, is discussed. It is unclear whether VEGF has a role in the etiopathogenesis of the endocrinopathies or perhaps it is simply a marker of disease activity, with a low disease activity correlating with the recovery of the thyroid function. Further studies are needed to elucidate the underlying mechanisms, although we suspect it likely involves, at least in part, inflammatory cytokines and angiogenic factors.