Dundar, Bilge

AimsMucinous cystic neoplasms (MCN) are defined by the presence of an ovarian‐type stroma (OTS). Once ovarian stroma has become a requirement for the diagnosis of MCNs, studies using this criterion have disclosed that MCNs are seen almost exclusively (97%) in women. The occurrence of MCNs (with ovarian stroma) in men is exceedingly rare and raises questions about the origin of OTS and the role of hormones in tumourigenesis. This study aims to investigate the clinical and histopathological features of pancreatic or hepatic MCNs in men.Methods and resultsWe examined the MCN cases in men and compared them with age‐matched women. We further investigated MCN in premenopausal and postmenopausal women to explore the impact of hormonal status.The stromal cellularity tended to be lower in men as compared to women; however, limited numbers prevented statistical significance. Clinical presentation, tumour location, body mass index and cyst complexity were similar between men and age‐matched women, similarly in pre‐ and postmenopausal woman groups. All MCN cases, regardless of gender or hormonal status, showed OTS with positivity for oestrogen receptor (ER), androgen receptor (AR) and SF‐1 immunostains. Additionally, the presence of AR and ER‐beta in lining epithelial cells, in addition to the stromal cells, raised the probability for a potential role for local hormonal signalling in the pathogenesis of these tumours.ConclusionsMCNs in men had overlapping histopathologic and immunohistochemical profiles with those in women, regardless of menopausal status.

Radioiodine ablation therapy is commonly used for patients with well-differentiated thyroid cancer. False-positive radioiodine uptake in benign cystic lesions on post-therapy SPECT/CT presents a recognized diagnostic challenge. Here, we present the case of a 33-year-old woman who underwent total thyroidectomy, followed by I-131 radioiodine therapy. Her post–I-131 therapy SPECT/CT revealed incidental radioiodine uptake in a diaphragmatic mesothelial cyst, prompting further investigation. She subsequently underwent a dedicated liver MRI and excision biopsy, both of which were negative for thyroid cancer metastasis. This case highlights the importance of identifying benign sources of radioiodine uptake to avoid unnecessary interventions.