Endocrine Abstracts

Neurofibromatosis type 1 is an autosomal dominant genetic disorder that results from loss of function of the neurofibromin gene, leading to failure of a tumor suppressor mechanism. Usually characterized by ‘café-au-lait’ spots, cutaneous neurofibromas, and a predisposition for tumorigenesis occurring in childhood, NF1 can have variable clinical expression, with ‘mildly symptomatic’ cases eluding diagnosis until adulthood.

A 53-year-old woman with mild clinical stigmata but no previous diagnosis of NF1, presented for endocrine assessment after the surgical excision of an oligosymptomatic pheochromocytoma. The voluminous (10.8 cm) cystic mass, located above the left kidney, was discovered incidentally on abdominal ultrasonography, confirmed by computed tomography and then surgically excised. The pathology report established pheochomocytoma, and serial imagining over the next year showed an expanding adrenal remnant (3.3–4.6 cm). At initial endocrine evaluation, the patient was hypertensive (150/90 mmHg) despite medication, but stable and without the ‘adrenergic spells’ of a pheochromocytoma. She presented with multiple ‘café-au-lait’ spots, freckling in the axillary and inframammary areas. Her daughter was diagnosed in childhood with NF type 1. Blood assays documented the normetanephrine hypersecretion (metanephrines=14–44 pg/ml, normetanephrines=436 pg/ml, chromogranin A=40 ng/ml), which suggested a paraganglioma. Normal PTH and calcitonin levels excluded MEN type 2. After adequate alpha followed by beta blocade the patient undewent complete left adrenalectomy, with biochemical and morphological remission of the pheochromocytoma for 1.5 years postoperatively. She remained hypertensive but with more easily controlled BP levels (probably essential hypertension). As screening for the endocrine features of NF1, she was tested for carcinoid tumors and hypothalamic-pituitary dysfunction but had normal serotonin levels and pituitary function.

Atypical in the context of a disorder involving predominantly the skin, skeleton and nervous system, and unusual in an undiagnosed adult patient, our case illustrates the rare, clinically mild, but possibly severe endocrine complications of NF1.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.