Background: The phaeochromocytoma of the adrenal gland scaled score (PASS) is used for histological reporting of phaeochromocytomas as a surrogate marker of malignant potential. A PASS score of ≥4 (of a maximum of 20) suggests an aggressive tumour and hence the importance of lifelong careful follow-up. However, the utility of the PASS score has been questioned recently due to the discordance between PASS score and clinical outcomes.
Aim: To review the PASS score in all patients who have undergone adrenalectomy at our unit over the last 14 years and review its usefulness in predicted aggressive/malignant potential.
Methods: We searched for patients who had undergone an adrenalectomy at our University Teaching Hospital between 1 July 2007 and 30 April 2019 using clinical codes and filtered those with histologically confirmed phaeochromocytoma. Basic demographic data, PASS score, clinical outcomes and duration of follow up were recorded.
Results: 40 patients were identified with an equal male:female split. One patient underwent bilateral adrenalectomy for bilateral phaeochromocytomas. Mean age at diagnosis was 56.2 years (range 2282). Mean tumour size was 5.8 cm (range 1.713). Onepatient had a PASS score of >15 who had metastatic disease at presentation. Three patients experienced recurrence of the phaeochromocytoma (one local, 2 distal) between 2 and 8 years after their adrenalectomy. All had a PASS score of 3. PASS score for the remaining 37 patients ranged between 0 and 8 with no evidence of recurrence of their disease so far.
Discussion: In our experience, the PASS score does not accurately predict the malignant or aggressive potential of phaeochromocytomas, in line with similar findings in the literature. Tumour heterogeneity and histological sampling may be contributing factors. Therefore, our clinical practice is to monitor all patients lifelong with regular clinical assessment and metanephrine measurement. There is a need for more accurate biomarkers to help predict recurrence and malignant potential.