Endocrine Abstracts

A 56 year old lady underwent laparoscopic adrenalectomy for an incidental right adrenal mass. Plasma metanephrines were elevated pre-op and histology revealed PCC with a PASS score of 0/20 with SDHB immunostaining +. She remained asymptomatic until 9 years later when she presented with palpitations and worsening hypertension. Plasma metanephrines were 3-4 times above reference range. She was also found to have goitre and USG/FNA revealed THY4 lesion for which she underwent total thyroidectomy. Thyroid Ca (pT3 NxMx follicular variant papillary thyroid carcinoma) – Rx with Radio-Iodine. Following diagnosis of bony metastasis from anatomical imaging and no avidity of the metastases with I131, MIBG, Gallium Dotatate and FDG PET were arranged. Out of the three imaging modalities, The FDG-PET showed the most metastatic deposits: nodal, splenic and extensive bone metastases (C2, right humeral head, body of sternum inferiorly, T11-2, L4). However, MIBG and Gallium scan were less sensitive, with the Gallium Dotatate showing the least metastatic deposits. She was commenced on denosumab and also doxazosin for alpha-blockade. She continues to undergo on going surveillance including annual metanephrines. This case highlights the relative inaccuracy of PASS score in predicting malignant behaviour in PCC. This patient presented with metastatic disease 9 years after initial surgery despite an R0 resection and no local recurrence. No pathogenic variant was detected in the usual PCC-PGL genes. It is also interesting to note less sensitive performance of Gallium Dotatate when compared to other functional imaging modalities in identifying metastatic sites which is often the case in Cluster 2 PCC. The current recommendation is for 10-year surveillance in PCC post-resection without a germ line mutation however, rarely, metastatic disease can occur after this period. This calls for more accurate scoring systems and possibly other sensitive tumour markers for surveillance. Analysis of the tumour for any possible somatic mutations may become a necessity in the future.