Many thanks for this valuable additional information on screening, regarding the significance of pheochromocytoma in neurofibromatosis. The incidence of these rare tumors stated in the literature—they have an overall population incidence of 2 to 8 per 100 000 adults (prevalence: 1 in 3000 births)—ranges from 0.1% to 7% in NF1 patients (1).
In a series by Petr and Else, mean age at diagnosis in this patient group was 42 years (2). Only 9 of the 17 patients in this cohort had hypertension, and 3 had cardiovascular crises in the context of elective surgeries. This justifies ruling out pheochromocytoma in NF1 patients before elective surgeries under general anesthetic, as indicated in the Mayo Clinic study cited by Dr. Koch.
In fact, it is currently thought that approximately one-quarter of pheochromocytomas become malignant, and metastasis has been observed as much as 20 years after removal of the primary tumor (3). This suggests that indicating screening for at-risk patients is also worthwhile, as with patients with Von Hippel–Lindau disease. On the other hand, it is worth noting that, of 850 NF1 patients who have been monitored only by the Hamburg outpatient neurofibromatosis department using whole-body MRI and follow-up since 2004, pheochromocytoma that has become malignant has so far been identified in only one patient.
Footnotes
Conflict of interest statement
The authors of both discussion pieces declare that no conflict of interest exists.
References
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