Adrenal cancer in neurofibromatosis type 1: case report and DNA analysis

Summary

Adrenal cortical carcinoma (ACC) has previously only been reported in eight patients with type 1 neurofibromatosis (NF1). There has not been any clear evidence of a causal association between NF1 gene mutations and adrenocortical malignancy development. We report the case of a 49-year-old female, with no family history of endocrinopathy, who was diagnosed with ACC on the background of NF1, due to a novel germline frame shift mutation (c.5452_5453delAT) in exon 37 of the NF1 gene. A left adrenal mass was detected by ultrasound and characterised by contrast computerised tomography (CT) scan. Biochemical tests showed mild hypercortisolism and androgen excess. A 24-h urinary steroid profile and ¹⁸flouro deoxy glucose PET suggested ACC. An open adrenalectomy was performed and histology confirmed ACC. This is the first reported case with DNA analysis, which demonstrated the loss of heterozygosity (LOH) at the NF1 locus in the adrenal cancer, supporting the hypothesis of an involvement of the NF1 gene in the pathogenesis of ACC. LOH analysis of the tumour suggests that the loss of neurofibromin in the adrenal cells may lead to tumour formation.

Learning points

• ACC is rare but should be considered in a patient with NF1 and adrenal mass when plasma metanephrines are normal.

• Urinary steroid metabolites and PET/CT are helpful in supporting evidence for ACC.

• The LOH at the NF1 region of the adrenal tumour supports the role of loss of neurofibromin in the development of ACC.