Familial and early recurrent pheochromocytoma in a child with a novel in-frame duplication variant of VHL

Abstract

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors often linked to underlying genetic variants. Genetic analysis can promote gene-adjusted, specific follow-up, and surveillance protocols for both patients and their families at risk. We report the case of a 7-yr-old boy with bilateral pheochromocytoma, which recurred a year after partial adrenalectomy. The patient's father developed bilateral pheochromocytomas at 25 yr of age. Both individuals possessed a novel heterogeneous in-frame duplication germline variant of VHL, yet neither exhibited other clinical manifestations of von Hippel-Lindau disease (VHL). Traditionally, VHL missense mutations have been associated with a higher risk of PPGL development, whereas truncating mutations typically confer a lower risk. In-frame duplication variants are rarely observed in patients with VHL but may lead to changes in the three-dimensional structure of the translated protein, similar to truncating variants. Our analysis suggests that these in-frame duplications of amino acids in specific regions may cause pheochromocytomas in a manner similar to missense variants. Further accumulation of VHL cases with various genotypes and standardized open-access worldwide databases, including longitudinal and specific clinical data linked to genotypes, is required. It is crucial to consider genetic analyses for pediatricians who may diagnose childhood-onset PPGL.

Keywords: in-frame variant; pheochromocytoma; von Hippel–Lindau disease (VHL).

Fig. 1.

Imaging and immunohistochemical analysis. Red arrows indicate lesions. A: Abdominal MRI shows a 4 cm lesion in the right adrenal gland and a 3 cm lesion in the left adrenal gland. B: ¹²³I-MIBG scintigraphy shows no evidence of metastasis. C: Abdominal CT revealing bilateral adrenal tumors. The right mass is 42 mm in size with predominant peripheral contrast and low internal contrast, whereas the left mass is 27 mm in size with homogeneous contrast. Enhanced CT with a nonionic contrast agent was conducted with written informed consent from the parent or guardian before surgery to better understand the positional relation between the masses and blood vessels (37). D: ¹⁸F-FDG PET/CT shows no evidence of metastasis.

Fig. 2.

Histopathological tissue analysis on bilateral adrenal tumors. Hematoxylin and eosin staining (A, × 400) and immunohistochemistry using chromogranin A (B, × 400) and Ki-67 (C, × 200). Bars indicate 100 μm. The left (33 × 30 × 28 mm) and right (48 × 38 × 33 mm) tumors scored one point (vascular invasion) and five points (central tumor necrosis, atypical mitotic figures, and vascular invasion) on the PASS. Both tumor tissues were positive for chromogranin A, and the positivity rates of Ki-67 were 2.3% and 9.5% for the left and right lesions, respectively.

Fig. 3.

Recurrent tumor on the right adrenal gland. Abdominal CT (A) and ¹²³I-MIBG scintigraphy (B and C) revealed a right adrenal tumor measuring 15 mm (red arrows) without metastasis. Histopathological tissue analysis (D) revealed a 9 × 14 × 13 mm tumor with hematoxylin-eosin (middle panel) and Ki-67 staining (× 400 and × 200, respectively). Bars indicate 100 μm. It scored one point (vascular invasion) on PASS. The positive rate of Ki-67 was 3.6%

Fig. 4.

Genetic analysis of VHL gene. A: Direct PCR sequencing analysis performed using DNA extracted from the peripheral blood of the patient and parents revealed a heterozygous in-frame germline variant in VHL (NM_000551.4, c.565_585dup, p.Glu189_Gln195dup) in the patient (II-1) and father (I-1). B: Schematic representation of the VHL gene and protein structure. The VHL gene comprises three exons (gray). Nucleotide numbers are indicated above the upper gene structures. The VHL protein structure with (GXEEX)₈ repeat motif (yellow), α-domain (green), and β-domain (blue). The hypoxia-inducible factor-alpha (HIF-α) binding site (residues 65–117) is within the β-domain, and the Elongin C binding site is indicated. Codon numbers are indicated below the lower protein structure. The variants are indicated in red. C: Family pedigree of the proband. The proband (II-1) and his father (I-1) harbored a VHL variant and developed bilateral pheochromocytomas (pheo).