Endocrine Abstracts

Up to 40% of pheochromocytoma cases have a genetic background. The prevalence of pheochromocytoma in neurofibromatosis type 1 (NF1) was reported to be from 0.1 to 5.7%. However, the actual incidence of pheochromocytoma in NF1 seems to be underestimated. Current recommendations on NF1 do not include systematic biochemical screening for the presence of pheochromocytoma. Our aim was to analyse clinicopathological characteristics of pheochromocytoma in the course of NF1 syndrome with additional comparison to non-NF1 cases. We performed a database search for pheochromocytoma patients, diagnosed and treated in Endocrinology Department, University Hospital in Cracow from 2005 to 2022. In the group of 183 patients with histologically confirmed pheochromocytoma, 8 cases with NF1 were identified (4.4%). The group of NF1 patients comprise 4 men and 4 women. Median patient’s age was 44 years (range: 29-70 years). Most cases were diagnosed incidentally (6/7). The most common manifestation of the disease was hypertension (5/8). In majority of patients (6/8), NF1 diagnosis was stated based on clinical picture, in two cases genetic testing was performed. The median size of the tumour was 4.2 cm (range: 2.4-10.8 cm). In all cases with preoperative 68Ga DOTATATE PET/CT imaging (3/8), pathological tracer uptake was seen. 24- hour urinary fractionated metanephrines were significantly elevated in 6 cases. One patient had aggressive, metastatic tumour, which subsequently led to patient’s death, the rest of patients remained disease-free during follow-up (median time: 44.5 months). One patient had synchronous bilateral disease. In three cases, accompanying neoplasms from different origin were observed (adrenocortical carcinoma, prostate cancer, GIST of the jejunum). PASS score was defined in 6 patients - in majority of cases it exceeded 3 (range 4-10). In 4 subjects, histopathological examination revealed composite pheochromocytoma with ganglioneuroma component. There were no significant differences between NF1 and non NF1 pheochromocytomas regarding sex, age, tumour size, PASS score, levels of metanephrines. In patients with NF1, composite pheochromocytoma was diagnosed much more often than in non-NF1 cases (with p value = 0.003). Pheochromocytoma in the course of NF1 is very often diagnosed incidentally. Most commonly it is manifested by hypertension, which could be easily overlooked. Sometimes it could metastasize, leading to patient’s death. A routine hormonal assessment towards pheochromocytoma in patients with NF1 may improve patient’s safety and treatment outcomes. NF1 should be excluded in all cases with composite pheochromocytoma, since this type of tumour is more commonly diagnosed in NF1 patients.